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X-shooter User Manual

1. 444444044400000R0R0nRnnnnnnnnnnnnnnnnnnnnne 17 2 1 Overview of the opto mechanical design 444usssnnnsnnnnnnnnnnnnnnnnnnn nenn 18 2 2 Description of the instrument sub systems 4444440ssnnnnsnnnnnnnnnennnnnnnnn nenn 18 2 2 1 The Backbone sssssssssnnnnnennnnnnnennnnnnnnennnnnnennnnnnnnesnnnnnennnnnnne nn 19 2 2 1 1 The Instrument Shutter and The calibration unit n 19 2 2 1 2 The Acquisition and Guiding side 028 22 ee 20 2213 Theile aaa a aa aa aka aha 21 2 2 1 4 The Acquisition and Guiding Camera cccceeeeeeeeeeeeneeeeeeeeeeteeeeeaaees 23 2 2 1 5 The dichroic box 4 444sssnnnennnnnnnnnnnnnnnnnnnnnnnnennnnnnnnnnnnnnnessnnnnrenn 24 2 2 1 6 The flexure compensation tip tilt mirrors eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeees 24 2 2 1 7 The Focal Reducer and Atmospheric Dispersion Correctors 25 2 2 2 ADCs problems and disabled ADCs observing mode in SLIT and IFU 26 2 2 3 Detector QE curves PERRERRERERRERREPERREHREREREEEREUERSERREREREE RRUREREERRSRERSEERHRERRERRERERSEERPERSERR 35 2 2 4 The UVB Spectrograph ccccccccccseeeeeeeeeeeeeeeeaaeeadeeeeeeeeeeeaaeaaeeeeeeeeeeeaaaeaaeees 35 2 2 4 1 Slit carriage SERROSPBRUERPRERPEHREEEREGERFREPEREREEFRECERBEEFEUERLECERCEFEEERITFHEEFPECERPEEPEUEREESPRCEREEEREERE 35 2 2 4 2 Optical layout een ernennen 36 2243 Deteclor wr
2. The Integral Field Unit is an image slicer that re images an input field of 4 x1 8 into a pseudo slit of 12 x0 6 The light from the central slice is directly transmitted to the spectrographs The two lateral sliced fields are reflected toward the two pairs of spherical mirrors and re aligned at both ends of the central slice in order to form the exit slit as illustrated in Figure 4 Due to these four reflections the throughput of the two lateral fields is reduced with respect to the directly transmitted central one The measured overall efficiency of the two lateral slitlets is 85 of the direct transmission but drops to 50 below 400 nm due to reduced coating efficiency in the blue An example of an IFU standard star is showed in Figure 5 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 22 of 161 Blue UVB arm Re Blue orders Red orders VIS arm Blue Red Blue orders Red orders Blue Red Blue orders Figure 5 IFU telluric standard star B type star One can note the three slices in each order of each arm The telluric absorption lines are easily visible in the VIS and NIR arms One can also note the effect of the atmospheric dispersion change of distance between the slices between blue and red orders in UVB VIS arms ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT M
3. VIS arm Red _ _ _ ARIE Red orders m PEEN N et NETT I vo ne Blue iI i 4 a hr n am mo Rn Lee gpi pi m I iW Wig gt Red NIR I ae an a a N an yi 1 77 Au 1 l ie WEM bial Wah Piian l m poy A i ea ring ff oy I ll A l om py AE RT I peresis panes e po ntl Win y 1 E Blue orders Figure 10 example of UVB top VIS middle and NIR bottom calibration frames Strong order curvature and varying slit tilt and scale are clearly visible Note for the NIR arm the higher thermal background in longer wavelength This is specially the case in the 11 order that corresponds to the K band ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 500f161 Table 11 X shooter spectral format These orders are cut for the slits with the K band blocking filter Order Min wavelength Blaze wavelength Max wavelength nm nm nm UVB 24 293 6 312 2 322 3 23 306 2 325 0 336 2 22 320 0 339 8 351 4 21 335 1 356 1 368 0 20 351 8 373 5 386 2 19 370 1 393 2 406 4 18 390 6 414 5 428 9 17 413 4 438 8 454 0 16 439 1 466 4 482 2 15 468 3 496 8 514 2 14 501 6 531 0 550 8 13 540 1 556 0 593 0 VIS 30 525 3 550 5 561 0 29 535 8 568 0 580 2 28 554 6 585 9 600 8 27 575 2 607 7 622 9 26 597 4 629 5 646 8 25 621 3 653 8 672 5 24 647 2 682 1 700 4 23 675 4 711 2 730 7 22 706 1 742
4. Delete XSHOOTER sit_acq 1 XSHOOTER sIt_obs_AutoNodOnsiit T Get Guide Star from CATALOGUE UVB Slit 1 0x11 RA of guide star 0 VIS Slit 0 9x11 DEC of guide star 0 NIR Slit 0 9x11 TE aT UVB Exposure time 5 Offset DEC 20 5 VIS Exposure time 10 Instrument A amp G Filter B VIS readout mode 100k 1pt hg TCCD Exposure time NIR Exposure time DIT 15 no of NIR sub integrations NDIT 1 Number of exposures for UVB det NE 1 Number of exposures for VIS det NEXP 1 Number of exposures for NIR det NINT 1 Nod throw length arcsec 5 Width of the jitter box arcsec 0 1 T Specify here in arcsec the blind offsets jumper of cycies from the reference acquisition star to Coto zero offset position at the end the science target Here movements from the acquisition star of 35 6 to the west and 20 5 to the north Positive value in RA moves the slit to the east Positive value in DEC moves the slit to the north Of course this corresponds to sky offsets It is important to note that the offsets in all templates are offsets on sky as in other Paranal instruments They are computed as follows the offset RA corresponds to delta RA xcos DEC and the offset DEC is the difference delta DEC ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany ES Q Doc Issue Date Page VLT MAN ESO 14650 4942 P97 19 08 2015 74 of 161 el o A Obs Des
5. Detector calibrations Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 151 of 161 Table 65 User and fixed keywords for XSHOOTER gen cal Bias XSHOOTER_gen_cal_Bias Free Parameters Keyword Range Default Value Label in P2PP DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB read out mode DET2 READ CLKDESCR_ see Table 5 100k 1pt hg VIS read out mode SEQ NEXPO UVB 0 100 1 UVB No of exposures SEQ NEXPO VIS 0 100 1 VIS No of exposure Fixed Value DET1 WIN1 UIT1 0 UVB exposure time DET2 WIN1 UIT1 0 VIS exposure time Table 66 User and fixed keywords for XSHOOTER gen cal DarkUVBVis XSHOOTER_gen_cal_DarkUVBVis Free Parameters Keyword Range Default Value Label in P2PP DET1 WIN1 UIT1 0 36000 3600 UVB Exposure Time DET1 READ CLKDESCR_ see Table 5 100k 1pt hg UVB read out mode DET2 WIN1 UIT1 0 36000 3600 VIS Exposure Time DET2 READ CLKDESCR _ see Table 5 100k 1pt hg VIS read out mode SEQ NEXPO UVB 0 100 1 UVB No of exposures SEQ NEXPO VIS 0 100 1 VIS No of exposures Fixed Value Table 67 User and fixed keywords for XSHOOTER gen cal DarkNIR XSHOOTER_gen_cal_DarkNIR Free Parameters Keyword Range Default Value Label in P2PP DET3 DIT 0 36000 NIR Exposure Time DET3 NDIT 1 20 1 Number of DITs SEQ NEXPO 0 100 3 No of NIR exposures F
6. Table 32 User defined and fixed parameters for XSHOOT Doc Issue Date Page ER slt_cal SpecphotStdOffset VLT MAN ESO 14650 4942 P97 19 08 2015 133 of 161 The template is identical to that for alternate object sky slit observations except for some of the default parameters XSHOOTER_slit_cal_SpecphotStdOffset Keyword Range Default Value Label in P2PP Free parameters INS OPTI3 NAME see Table 4 5 0x11 UVB slit INS OPTI4 NAME see Table 7 5 0x11 VIS slit INS OPTI5 NAME see Table 8 5 0x11 NIR slit DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXP UVB 0 100 1 UVB number of exposures per offset position SEQ NEXP VIS 0 100 1 VIS number of exposures per offset position SEQ NEXP NIR 0 100 1 NIR number of exposures per offset position SEQ FIXOFF RA 100 100 0 RA fixed offset SEQ FIXOFF DEC 100 100 0 DEC fixed offset SEQ JITTER WIDTH 0 2 0 Jitter box width in SEQ NABCYCLES 0 100 1 Number OS or SO cycles SEQ OFFSET ZERO TF T Return to Origin Fixed Values INS MODE SLITSPEC SLITSPEC Instrument Mode IFUSPEC SEQ AGSNAPSHOT T E F Take an acquisition image before scienc
7. RON 1c S 1 F w D a 0 5 a s G a u 9 i Z u i me Tai ane u a n oeo Mu p gt am 2 0 En w LE Zu 2 ease Em u amp s 2 bee a a M mS nn 0 5 B S ae Lr on 5D e o a A D a a e 1 S gt e 1 5 e z 2 56660 56670 56680 56690 56700 56710 56720 56730 MJD c the long term stability of the instrument was tested with the spectrophotometric standard star EG274 observed during a period of more than 500 days However the star was quite often observed under sub optimal condition twilight with fast variable sky background etc Nevertheless the RMS is of 0 42 over 1 4 years EG274 photometric transparency seeing lt 1 3 no early twilight 2 0 1 5 Pa x Em P 1 0 Vv Ca 0 5 a ee ee a a a a ee al F T n i 0 0 a 7 5 E Fa u g t a z a m mi Amel der See S dee 4 eames el 0 5 E E I 1 0 56000 56100 56200 56300 56400 56500 56600 MJD d the noise structure background unfortunately follows the ambient temperature evolution The Peltier that cools down the detector is cooled down with a coolant flow Unfortunately if there is an ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 91 of 161 ambient temperature increase or if the temperature is high the Peltier is not cooled down fast enough and the background noise structure is higher However despite t
8. ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 124 of 161 7 1 4 Flexure compensation templates that can be used in OBs Two new templates are available in order to provide the possibility for the user to do additional flexure compensations in case of a long OB longer than 1h 1h15mn This new kind of template can be inserted between 2 science templates for instance In all cases the flexures compensation is always performed at the beginning of an OB through the acquisition template Thus for usual OB shorter than 1h 1h15mn there are no needs to add this kind of template In case of slit observation you could use the XSHOOTER_sit_AFC template In case of IFU observation you could use the XSHOOTER_ifu_ AFC template 7 1 5 Science templates Slit observations The SEQ AGSNAPSHOT is not available because a snapshot of the A amp G camera is saved at the end of the acquisition Table 22 Parameters for stare mode observations with the template XSHOOTER slt obs Stare XSHOOTER_slt_obs_Stare Keyword Range Default Value Label in P2PP Free parameters INS OPTI3 NAME see Table 4 1 0x11 UVB slit INS OPTI4 NAME see Table 7 0 9x11 VIS slit INS OPTI5 NAME see Table 8 0 9x11 NIR slit DET1 WIN1 UIT1 0 36000 UVB Exposure Time s DET1 READ CLKDESCR see Table 5 100k 1pt hg
9. TEL ROT OFFANGLE 179 99 179 99 9999 Slit position angle on Sky 9999 9999 for parallactic angle INS FILT1 NAME u g r i z U B A amp G filter V R I DET4 WIN1 UIT1 0 36000 TCCD exposure time TEL AG GUIDESTAR CATALOGUE CATALOGUE Telescope guide star SETUPFILE selection mode NONE TEL GS1 ALPHA 0 0 Guide Star RA TEL GS1 DELTA 0 0 Guide Star DEC Fixed parameters DET1 WIN1 UIT1 2 AFC UVB exposure time DET2 WIN1 UIT1 0 5 AFC VIS exposure time DET3 DIT 1 AFC NIR DIT DET3 NDIT 1 number of AFC NIR DITs SEQ AFC CORRECT F T T AFC correct flag SEQ AFC WSIZE 64 Window size for AFC Cross Correlation SEQ AFC MAXD 20 Maximum distance for AFC Cross Correlation SEQ PRESET T F T Preset flag INS MODE SLITSPEC SLITSPEC Instrument mode IFUSPEC ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany IFU acquisition templates Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 122 of 161 Table 20 User defined and fixed parameters for XSHOOTER ifu acq XSHOOTER_ifu_acq Keyword Range Default Value Label in P2PP Free parameters TEL TARG ALPHA 000000 000 Target RA TEL TARG DELTA 000000 000 Target DEC TEL TARG EQUINOX 2000 3000 2000 Equinox TEL TARG EPOCH 1950 2000 2000 Epoch TEL TARG PMA 10 0 10 0 0 0 RA proper motion year TEL TARG PMD 10 0 10 0 0 0 DEC proper mo
10. spaced at 1 4 GAL 0 5 pinhole CAL ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 36o0f 161 2 2 4 2 Optical layout Entrance slit nr out of the plane Main mirror Folding mirror 1 x Folding mirror 2 Grating Corrector lens Detector CCD 2Kx4K tilted surface Figure 7 The UVB spectrograph optical layout The optical layout of the UVB spectrograph is presented in Figure 7 Light from the entrance slit placed behind the plane of the figure feeds a 5 off axis Maksutov type collimator through a folding mirror The collimator consists of a spherical mirror and a diverging fused silica corrector lens with only spherical surfaces The collimated beam passes through a 60 silica prism twice to gain enough cross dispersion Main dispersion is achieved through a 180 grooves mm chelle grating blazed at 41 77 The off blaze angle is 0 0 while the off plane angle is 2 2 After dispersion the collimator creates an intermediate spectrum near the entrance slit where a second folding mirror has been placed This folding mirror acts also as field mirror Then a dioptric camera 4 lens groups with CaF2 or silica lenses 1 aspherical surface reimages the cross dispersed spectrum at f 2 7 plate scale 9 31 mm onto a detector that is slightly tilted to compensate for a variation of best
11. ER ifu cal VISLampFlatAtt XSHOOTER_ifu_cal_VISLampFlatAtt Keyword Range Default Value Label in P2PP Free Parameters DET2 WIN1 UIT1 0 36000 VIS exposure time DET2 READ CLKDESCR see Table 5 VIS readout mode SEQ NEXPO 0 100 No of exposures Fixed Value INS MODE IFUSPEC SLITSPEC IFUSPEC Instrument Mode ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 143 of 161 Table 47 Parameters for the template xSHOOTER ifu cal NIRLampFlatAtt XSHOOTER_ifu_cal_NIRLampFlatAtt Keyword Range Default Value Label in P2PP Free Parameters DET3 DIT 0 36000 60 NIR exposure time DIT DET3 NDIT 0 20 1 No of NIR sub integrations SEQ NEXPO 0 100 No of exposures Fixed Value INS MODE IFUSPEC SLITSPEC IFUSPEC Instrument Mode ADDITIONAL POSSIBLE NIGHT calibrations to insure a better wavelength calibration one can use the ARC multipinhole templates at night They do not need to be executed after a science template because they configure the instrument Of course it also adds some overheads due to the various instrument reconfigurations Arcs multi pinhole 2d wave maps wavelength calibration Table 49 User and fixed keywords for XSHOOTER slt cal UVBVisArcsMultiplePinhole Keyword DETI WIN1 UIT1 DET1 READ CLKDESCR DET
12. ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Table 34 User defined and fixed parameters for XSHOOT Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 135 of 161 template is identical to that for the IFU observations in stare mode ER ifu cal SpecphotStdStare The XSHOOTER _ifu_cal_SpecphotStdStare Keyword Range Default Value Label in P2PP Free parameters DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXP UVB 0 100 1 UVB number of exposures SEQ NEXP VIS 0 100 1 VIS number of exposures SEQ NEXP NIR 0 100 1 NIR number of exposures Fixed Values INS MODE SLITSPEC IFUSPEC IFUSPEC Instrument Mode INS OPTI3 NAME see Table 4 1x12 6 UVB slit INS OPTI4 NAME see Table 7 1x12 6 VIS slit INS OPTI5 NAME see Table 8 1x12 6 NIR slit SEQ AGSNAPSHOT mE F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Table 35 User defined and fixed parameters for XSHOOT template is identical to the XSHOOT Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 136 of 161 E
13. To take attached calibrations the attached calibration template MUST come after the corresponding science template because it will use the setup of the instrument performed by the science template Therefore if one needs to bracket the observations by attached flat fields he she needs to create an OB like this Acquisition template dummy exposures in a science template for instrument setup attached calibration here flat fields normal observation with the science template attached calibration If one does directly the attached calibration after the acquisition template the system will use the setup corresponding to the AFC 6 6 Spectrophotometric calibration 6 6 1 Telluric absorption correction The visual red and a near IR part of the spectrum are strongly affected by the absorption lines of the Earth s atmosphere Many of these telluric lines do not scale linearly with airmass so it is necessary to observe a star with a well known spectrum at the same airmass and with the same instrument setup as that used for the science target Furthermore the strength of the telluric lines varies with time so it is also necessary to observe the telluric standard soon after or just before the science observation Two templates are designed for this purpose XSHOOTER slt cal TelluricStd and XSHOOTER ifu cal TelluricStd In general we use either main sequence hot stars BO to B4 whenever possible or to B9 otherwise or solar analogs as t
14. offset C RA 20 DEC 0 offset D RA 0 DEC 10 offset E RA 10 DEC 0 And the telescope is back to the original position ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc Issue Date Page VLT MAN ESO 14650 4942 P97 19 08 2015 117 of 161 UVB Figure 19 The slit coordinate system and correspondence between object position in the slit and position on the spectrum for each arm An object at positive x black star top panel produces spectra placed as illustrated in the bottom panels NOTE a positive offset in the x or y direction will move the object in direction of x and y axis Note that the keyword ADA POSANG in the header indicates the opposite of the slit angle specified by the user It corresponds to the rotator angle ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 118 of 161 7 1 2 Examples of position angles and offsets TEL ROT OFFANGLE is the keyword in the acquisition templates to set up the slit position angle on sky A value of 9999 default means that the parallactic angle is used The parallactic angle is not followed during the exposure the system uses the parallactic angle at the start of the OB If another PA is defined the telescope will follow this angle on sky h Examples of position angles If the user needs a position angle of
15. In the following pages you will find useful information characterizing the observations without working ADCs to compensate the atmospheric dispersion in UVB and VIS arms Measurements were performed in the various orders of the UVB VIS arms some comparisons are performed and the average the min max values and the standard deviation are provided The slits used are 1 0 0 9 0 9 in the UVB VIS and NIR arms respectively In 2015 a study has been launched to repair the ADCs if successful the repaired ADCs will be made available possibly in 2016 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc Issue Date Page a Atmospheric dispersion effect on the XSHOOTER spectra without ADCs The tracking in XSHOOTER is by default 470nm and The dispersion effect of the atmosphere on XSHOOTER spectra depends on the tracking wavelength used by default 470nm Therefore the current effect is shown in the following plots for the UVB VIS and NIR arms VLT MAN ESO 14650 4942 P97 19 08 2015 27 of 161 a 3122 0 3561 0 UVB arm R 3932 0 4145 0 4388 0 4664 0 m 5016 0 5560 0 5 Ji y 7 _ S ook S amp fi amp 1 0 15 240 12 14 1 1 8 0 Aim 10 5505 0 VIS arm 5859 0 6538 0 7112 0 7776 0 8602 0 9573 0 10016 0 A 195 I 16 NIR arm 10058 0 11370 0 13763 0 16344 0 20115 0 23773 0 12 1 4 16 Angs
16. In this subsection a summary is presented first a modeling for narrower slits is shown in second and finally the detailed measurements corresponding to the first part are provided We consider here the ratios of the observation at 45 degrees or 90 degrees of the parallactic angle to the parallactic angle for different airmasses Summary Arm airmass Ratio 45 parall Ratio 90 parall UVB 1 10 0 98 0 83 UVB 1 51 0 84 0 63 UVB 2 20 0 31 0 18 VIS 1 10 0 87 0 80 VIS 1 51 0 92 0 72 VIS 2 20 0 63 0 31 The similar information was computed theoretically and is shown in the following plots 50 E 40 4 2 30 4 20 4 D 10 J e Z 0 3000 3500 4000 4500 5000 5500 Wavelength A T T b O U ul 25 of light entering slit w oO 20 6000 7000 8000 9000 10000 Wavelength A On those plots for observations at 90 degrees of the parallactic angle slits of 0 4 in the UVB arm top 0 5 in the VIS arm bottom and a seeing of 0 8 have been considered ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 300f161 Arm airmass Type of ratio average range std UVB 1 10 45 parall 0 98 0 84 1 0 0 19 UVB 1 10 90 parall 0 83 0 74 1 0 0 15 UVB 1 51 45 parall 0 84 0 56 1 0 0 13 UVB 1 51 90 parall 0 63 0 25 1 0 0 26 UVB 2 20
17. European Organisation Organisation Europ amp enne Europ ische Organisation for Astronomical pour des Recherches f r astronomische Research in the Astronomiques Forschung in der Southern Hemisphere dans H misphe re Austral s dlichen Hemisphare VERY LARGE TELESCOPE X shooter User Manual Doc No VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Prepared Christophe Martayan originally written by Jo l Vernet amp Elena Mason Name Date Signature Approved Andreas Kaufer originally approved by Sandro D Odorico Name Date Signature Released Steffen Mieske Christophe Dumas Name Date Signature ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 2 of 161 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 3 of 161 CHANGE RECORD ISSUE DATE SECTION PARA REASON INITIATION AFFECTED DOCUMENTS REMARKS 13 01 06 FDR version Table of Content prepared by C line P roux 0 2 14 08 08 All PAE version prepared by Jo l Vernet 1 01 03 09 All First release prepared by Jo l Vernet with contributions by Elena Mason 2 01 07 09 All Prepared by Jo l Vernet and Elena Mason Added description of IFU centring and tracking wavelength Updated all TSF in Sec 5 Added spectrograph orientation figure Added description of Threshold
18. ONewri ffi Edit X Delete click New TI to add a new Time Interval click on a Time Interval to select it If needed in case of time critical observation add a constraint in the time interval range of dates and times ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 72 of 161 ES demonstration Yo w amp a gt Obs Description Target Constraint Set ime Interva Time Intervals Sidereal time 11 30 11 45 12 00 12 15 12 30 08 30 08 45 09 00 09 15 0930 09 45 10 00 10 15 10 30 10 45 11 00 11 15 12 45 Time Intervals O New TI fi Edit X Delete click New TI to add a new Time Interval click on a Time Interval to select it Only if actually needed you can also define a range of valid sidereal times for the observation of your target ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 730f161 rl demonstration WY amp AE AIl Obs Descriptionff Target Constraint Set Time Intervals OD Name en User Comments BLIND OFFSET ACQUISITION Instrument Comments Execution Time Recalculate TemplateType acquisition Template e XSHOOTER_ifu_acq_rrm SHOOTER slt_acq_rrm Duplicate XSHOOTER_ifu_acq
19. dutie hooterfmoveut2to IRAF Image Reduction and Analysis Facility PACKAGE immatch TASK imcombine input D Blistebias List of images to combine output masterbias fits List of output images Cheaders gt List of header files optional bpmasks gt List of bad pixel masks optional rejmask gt List of rejection masks optional Cnrejmas gt List of number rejected masks optional Cexpmask gt List of exposure masks optional sigmas gt List of sigma images optional Cimemb I Keyword for IMCMHB keywords logfile STDOUT Log file combine median Type of combine operation reject minmax Type of rejection project no Project highest dimension of input images Couttype real Output image pixel datatype outlimi gt Output limits x1 x2 yl y2 3 Coffsets none Input image offsets masktyp none Mask type maskval O Mask value blank 0 Value if there are no pixels scale none Image scaling zero none Image zero point offset weight none Image weights statsec gt Image section for computing statistics Cexpname gt Image header exposure time keyword 1thresh INDEF Lower threshold Chthresh INDEF Upper threshold Cnlow 1 minmax Number of low pixels to reject Cnhigh 1 minmax Number of high pixels to reject nkeep 1 Minimum to keep Tpos or maximum to reject neg mclip yes Use median in sigma clipping algorithms lsigma 3 Lower sigma clipping factor Chsig
20. e XSHOOTER slt cal UVBLowLampFlat UVB deuterium D lamp flat e XSHOOTER slt cal UVBHighLampFlat UVB halogen lamp flat e XSHOOTER slt cal VISLampFlat e XSHOOTER slt cal NIRLampFlat And their equivalent for IFU flatfield named XSHOOTER_ifu_cal_ LampFlat Note that low frequency fringes with peak to valley amplitudes up to 5 are present in the red part of the VIS spectra Table 17 exposure time for arc frames and flat field frames Values are given for the fast readout low gain mode in UVB and VIS for a 1 0 or 0 9 slit and the IFU For the flatfield values can be adapted to other slit widths and readout modes applying a simple scaling These values depend on the lamp but should be closed to those indicated in this table UVB VIS NIR 1x1 low gain 1x1 low gain ThAr arc lamp Slit 1 0 30 s TBC Slit 0 9 5s Slit 0 9 0 66 s IFU 45 s TBC IFU 4 s TBC IFU 1 32 s 9 pin 15s 9 pin 10s 9 pin 0 66 s Flatfield i j Do 7 38 z A Slit 1 0 als 193 8 Slit 0 9 18 8 s Slit 0 9 20s D2 14s IFU Halo 325 IFU 52 s IFU 30 s ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc Issue Date Page 6 4 Spectroscopic skyflats VLT MAN ESO 14650 4942 P97 19 08 2015 109 of 161 It is now possible to request the support astronomers to take spectroscopic skyflats both slit and IFU modes They will be taken on the best effort basis The performed tests show tha
21. slit 1307 x 2875 CAL 3 1 5 x11 slit 392 x 2875 SCI CAL 4 1 2 x11 slit 314 x 2875 SCI CAL 5 0 7 x11 slit 183 x 2875 SCI CAL 6 1 0 x 12 6 slit 261 x 3294 With IFU only 7 Raw of 9 pinholes of 0 5 131 holes spaced by CAL spaced at 1 4 352 8 0 4 x11 slit 105 x 2875 SCI CAL 9 0 9 x11 slit 235 x 2875 SCI CAL ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 161 of 161 72 3 NIR Table 73 full description of the new NIR slit mask Position Size Physcal size Purpose 1 0 5 pinhole 0 490 CAL 2 5 x11 slit 5 004 SCI CAL 3 0 9 x11 slit 0 917 SCI CAL 4 1 0 x 12 6 slit 0 991 With IFU only 5 1 2 x11 slit 1 191 SCI CAL 6 tilted slit TECH focus 7 0 6 x11 JH 0 623 SCI CAL 8 Blind 9 0 9 x11 JH 0 904 SCI CAL 10 0 4 x11 slit 0 386 SCI CAL Raw of 9 pinholes of m 0 5 spaced at 1 4 vee GAL 12 0 6 x11 slit 0 612 SCI CAL Table 74 full description of the old NIR slit mask Position Size Physcal size um Purpose 1 0 5 pinhole 270 hole CAL 2 5 x11 slit 2695x5683 CAL 3 0 9 x11 slit 485x5683 SCI CAL 4 1 0 x12 6 slit 544x6510 With IFU only 5 1 2 x11 slit 647x5683 SCI CAL 6 tilted slit TECH focus 7 1 5 x11 slit 8 Blind 9 0 4 pinhole 216 hole TECH 10 0 4 x 11 slit
22. the use of the SLIT mode if you are interested by the core of the galaxy or by the star is OK However the sky correction will be difficult Doing the NODDING is useless in such case because after offset the slit will still be in the surrounding environment galaxy disk or nebula The use of the STARE mode is OK and the sky lines correction is performed with the pipeline In addition in case of extended object you will also get spatial information along the slit In such case you can choose to specify another position angle than the default one that is the parallactic angle Note that with the pipeline you can select the region of spectra extraction and extract in a first iteration the object spectrum and in a second iteration the nebula spectrum for instance see the data reduction cookbook that is coming soon The FIXED OFFSET or GENERIC OFFSET observing modes are suitable With the first one you will do the couple of observation object sky positions With the second one you are able to do a mapping of the environment and also do offset to sky position However in the GENERIC OFFSET template all the offset values are cumulative and refer to the current position see also Sect 7 1 1 With both templates the number of exposures on sky and object must be the same This is the same for the exposure times The MAPPING templates are not restricted with respect to the number of sky or object positions and exposure times e Extended
23. NIR darks N A N A 3 per DIT daily Master dark bad pix map IFU UVB VIS NIR 1 D2 1 halo 1 1 ON OFF Bi daily IFU FF for monitoring of the flats lamp UVB VIS ADCs and the IFU 5 setting D2 Pixel to pixel variations blaze SIit IFU flats 5 Ba 5 setting 5 ON OFF daily en When iiggered lamp Arcs single Pipeline calibration first guess pinhole Th Ar or 1 1 1 ON OFF Every 2 days disp solution Ar Xe Hg Kr FMCK Flat single 1 Dz lamp Pipeline calibration order pinhole 1 Halo lamp 1 1 ON OFF Every 2 days localization ORDERDEF i 1x1 binning in UVB VIS Arcs multi pinhole Wavelength and spatial scale Th Ar or 1 1 1 ON OFF Every 2 days determination calibration Ar Xe Hg Kr WAVE Arcs through Wavelength shift between multi slit IFU 1 ON OFF inholes and slits spectral Th Ar or 1 setting 1 setting setting daily such ARC none taken in Ar Xe Hg Kr 2x2 due to remnants Flat multi pinhole 1 1 1 ON OFF On request Hag definitioh laken on IFU slitlet 2 2 2 6 monthly Pipeline calibration cube distances TBC reconstruction Radial velocity 2 2 2 On request Accurate radial vel calibration standard Correct for telluric abs Only in Telluric standard 1 1 1 1 obs stare mode in SM up to P90 in 2 P91 2 P91 2 P91 nodding starting from P91 No 5 slits observations Response curve absolute flux calib In nodding mode in slit Speciro i mode it is taken every time the photometric 2 2 2 daily instrument is used in IFU mode standard onl
24. SLITSPEC Instrument Mode IFUSPEC SEQ AGSNAPSHOT TE F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Table 25 Parameters for the template XSHOOT object and sky observations by couple Doc Issue Date Page VLT MAN ESO 14650 4942 P97 19 08 2015 127 of 161 ER slt_obs FixedSkyOffset lIt allows to alternate XSHOOTER_slit_obs_FixedSkyOffset Keyword Range Default Value Label in P2PP Free parameters INS OPTI3 NAME see Table 4 1 0x11 UVB slit INS OPTI4 NAME see Table 7 0 9x11 VIS slit INS OPTI5 NAME see Table 8 0 9x11 NIR slit DET1 WIN1 UIT1 0 36000 UVB Exposure Time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB read out mode DET2 WIN1 UIT1 0 36000 VIS Exposure Time s DET2 READ CLKDESCR see Table 5 100k 1 pt hg VIS read out mode DET3 DIT 0 66 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXP UVB 0 100 1 UVB number of exposures per offset position SEQ NEXP VIS 0 100 1 VIS number of exposures per offset position SEQ NEXP NIR 0 100 1 NIR number of exposures per offset position SEQ FIXOFF RA 100 100 0 RA fixed offset SEQ FIXOFF DEC 100 100 0 DEC fixed offset SEQ JITTER WIDTH 0 2 0 Jitter box width in SEQ NABCYCLES 0 100 1 Number OS or SO cycles SEQ OFFSET ZERO T F T Return to Origin Fixed Values
25. 2 4 7 2 4 14 Homogenizing the overheads and references Adding the mapping templates information Adding offset convention at Paranal obvious info about mapping tpl and how to use the imaging mode Pelletier cooling effect Minor editing for P97 phase1 adding section about historical wavelength shift between arms ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 8 of 161 TABLE OF CONTENTS 1 Introduction 22244444404HHHnnnnennnnnnnnnennnnnnennnnnnnnnnnnnnnennnnnnnnennnannnnrnnnnnnenssnnnnrennn 11 1 1 SCOPE MRE PAIUINBEEUNFENBEREHERUNELUEUN EETHERDLTERNEUNGER VEENELEREEEELEELUEENLEERHFERELELUEUNELERNEERFLELUERNLERRNFENER 12 1 2 X shooter in a nutshell 0ss20ssnsnnnnennnnnnnnnnnnnnnennnnnnnnnnnnnnnennnnnnennnnnnnnn 12 1 3 Shortcuts to most relevant facts for proposal preparation cccccceeeeeeeeeeeeeeeees 12 1 4 List of Abbreviations amp Acronyms 44444ssnsennnnsnnnnnnnnnnunnnnnnnnnnnnnnnnnnnnnnnnnn nn 13 1 5 Reference Documents cccccccccccccceceeeeeeeeeeeecceeeeeceeceeeceeeeeeeeceseeeeeeeeeeeeeseeeeesess 14 1 6 Fate inlei v 6 01 40 10 1 SPRREHEREERPENREEFEHCHERELETEHHEEFEEUUEREELFEHHEREPRCHERLERTEHHEEFEICUEREELFEHHEEFERCHERLELFENE 15 1 7 CONAC a fact ifndef aig essen A 15 1 8 NEWS ee era ee erh ern een 16 Technical description of the instrument
26. 216x5683 SCI CAL 44 Raw of 9 pinholes of 0 5 270 holes spaced by CAL spaced at 1 4 723 12 0 6 x11 slit 323x5683 SCI CAL ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany
27. 3 3 Examples of OBs preparations acquisitions with p2pp3 Note that in SM our USD colleagues will help you in case of questions regarding the preparation of the OBs In VM there is a support from the astronomers at Paranal 3 3 1 Direct acquisition BIS demonstration AIN EFE 4 pe ae Obs De pion Target Constraint Set Time Intervals Obs Description OD Name demonstration_direct_acquisition User Comments Instrument Comments Execution Time Choose the TemplateType acquisition Template acquisition template Add XSHOOTER_ifu_acq_rrm IXSHOOTER_sIt_acq_rrm XSHOOTER_ifu_acq XSHOOTER_sIt_acq 1 Get Guide Star from CATALOGUE RA of guide star 0 VLT guide star DEC of guide star 0 Position Angle on Sky 9999 0 an Offset RA 0 Slit position angle Offset DEC 0 i Instrument A amp G Filter B 9999 pa rallactic TCCD Exposure time 1 angle Choose filter integration time of TCCD ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 68 of 161 amp WY demonstration wo g Obs Description Target Constraint Set Time Intervals rObs Description OD Name demonstration_direct_acquisition User Comments Instrument Comments Execution Time 00 00 00 000 Recalculate Science template
28. 5 2 4 3 3 4 3 4 1 2 5 1 5 4 Table 16 revised Clarification of 2 2 4 3 new NIR slits New 6 1 2 for better explanation of slit orientation and offsets No ADCs mode sect 2 2 2 updates of sects 2 4 2 24 13 1 4 15 3 1 3 4 3 5 7 5 9 DIT of 1800s with JH slits TCCD limiting magnitudes direct acquisition Telluric std star observations How to minimize the overheads and optimize the integration times Calibration plan revised Phase 2 minor modifications re writing sentences new draws contacts added at the beginning already present in other pages Other minor adjustments of the tables and links Adding a new section about the observations without ADCs 2 2 2 Updates of sections for the observations in slit with disabled ADCs more infos for the IFU Updates wrt the telluric std star policy starting in P91 Transmission curve of the K band blocking filter added Telluric std star policy updated for P91 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany 91 92 P92 P93 Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 6 of 161 10 02 2013 Section 3 2 split in 2 3 2 1 3 2 2 New section 3 3 New section 1 6 Sects 3 2 1 3 2 2 main acq loop and 3 2 2 blind offset precision New section 3 3 about examples of OBs preparation with p2pp3 especially regarding the acqs direct or blind offsets new section 1 6 regarding the acknowle
29. 6 763 8 21 739 7 777 6 800 0 20 777 0 815 8 839 8 19 817 6 860 2 883 8 18 862 9 904 3 932 7 17 913 7 957 3 987 4 16 970 7 1001 6 1048 9 NIR 26 982 7 1005 8 1034 2 25 1020 5 1046 0 1076 7 24 1062 0 1089 6 1122 9 23 1106 6 1137 0 1173 1 22 1155 2 1188 6 1228 0 21 1208 2 1245 2 1288 5 20 1266 5 1307 5 1355 2 19 1330 3 1376 3 1429 4 18 1400 8 1452 8 1511 5 17 1479 5 1538 2 1604 0 16 1567 1 1634 4 1708 7 15 1667 8 1743 3 1823 3 14 1785 7 1867 9 1952 8 13 1922 6 2011 5 2102 0 12 2082 9 2179 3 2275 6 11 2272 3 2377 28 2480 7 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 51 of 161 2 3 Spectral format resolution and overall performances 2 3 1 Spectral format The spectral format of X shooter is fixed The spectral ranges on the detector and blaze wavelength for each order are given in Table 11 and an example of ThAr slit frame for each arm is shown Figure 10 The whole spectral range is covered by 12 orders in the UVB 15 in the VIS and 16 in the NIR Orders are strongly curved parabolic and the spectral line tilt varies along orders Both slit height and width projection also vary from order to order and along each order due to a variable anamorphic effect introduced by the prisms crossed twice For instance the projected slit height 11 measured at the center of an order changes from e UVB 65 9 pixels 0 167 pix at order
30. 77 3 4 5 Fixed offset to sky SLIT and IFU ccccccceeeeeeeeseececeeeeeeeeeeeensaaeeeeeeeeeeeeeees 78 3 4 6 Generic offset SLIT and IFU ren ee 78 3 4 7 Mapping SLIT and IFU templates cccecceeeeeeeeeseneceeeeeeeeeeeteesaeeeeeeees 78 3 5 Observation strategy summary and tricks 2222244444snnennnnnnnnnnnnnnnnnnnnnnnnnnnnnnn 79 3 5 1 Instrument setup 222444404444sannnnnnnnnnnnnennnnnnnnnnnnnnennnnnnennnnnnnnnsssnnnrenn 79 3 5 2 Observation strategy 244444400nnn4nnnnnnnnnnnnnnnnnnnnnnnnnnnnannnnnannnnnnnnnnnannnnnnnnn 80 3 5 3 Telluric standard stars and telluric lines correction see also Sect 6 6 1 82 3 5 4 Observing bright objects limiting magnitudes and the diaphragm mode 82 3 5 5 Readout times in the UVB and VIS arms minimization of overheads 83 The XSHOOTER imaging mode 2244444444snnennnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nenn 84 Instrument and telescope Overheads ccccceccceeeeeeeeeeeeeeeeeaaeeeeeeeeeeeeeaaaenseneeeeees 100 5 1 1 Summary of telescope and instrument overheadS enn 100 5 1 2 Execution time computation and how to minimize the overheads 102 Calibrating and reducing X shooter data s22244444444nnnennnnnnnennnnnnnnnennnnnnnnnnnnn 104 6 1 X shooter Calibration Plan 2 0 0 cc ccccceeeeeeeceeceeeeeaeeeeeeeeeeeeeeeeaaeaeeeeeeeeeeeeaaaeseeeeeeeees 1
31. Acquisition and Guiding slide reference pinhole corrected in real time from effects of atmospheric refraction between the wavelength of the selected acquisition filter and the telescope tracking wavelength 470 nm for SLIT mode user selected for IFU observations In the coming period P93 a snapshot will only be taken at the end of the acquisition process for a direct acquisition and in case of blind offset a snapshot will be taken before and after the blind offset Loop over steps 5 and 6 When the observer is satisfied with the object centring an acquisition image is saved and the Acquisition and Guiding slide is either set to the spectroscopic observations position 10 x 15 slot in SLIT mode or to the IFU position along with other mode specific instrument setup In alternative to step 8 in case of a blind offset the offsets are applied before acquiring the final image and moving to spectroscopic observation position Note that the blind offsets are mandatory in case the target is too faint to be acquired directly At this point the instrument is ready for science observations This acquisition sequence is performed by one of the two acquisition templates XSHOOTER slt acq or XSHOOTER ifu acq also the RRM possibility depending on the selected observing mode A full description of these templates is given in section 7 1 3 Note that the instrument setup is done within the acquisition template so that for instance an IFU observation
32. Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 42 of 161 Below one can see flat field frames for the slits with and without K band blocking filter ON OFF Flat field frames for the normal 0 9 NIR slit top and for the 0 9 with blocking filter bottom One can easily note that the last orders are cut by the K band blocking filter ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 43 of 161 ON OFF Flat field frames for the normal 0 6 NIR slit top and for the 0 6 with blocking filter bottom One can easily note that the last orders are cut by the K band blocking filter ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany 2 2 6 3 NIR Backgrounds Doc Issue Date Page VLT MAN ESO 14650 4942 P97 19 08 2015 44 of 161 The background of the new slits 0 6 JH and 0 9 JH with the blocking filter was compared to the background of the normal slits 0 6 and 0 9 The table 11 below gives example of the background measurements at different wavelengths for slits with and without filter Table 10 Background measurements of the slits with and without filter The measurements were normalized to a theoretical 1 slit The RON is not included here Background Background eer Wavelength with filter without filter Reduction in
33. INS MODE SLITSPEC SLITSPEC Instrument Mode IFUSPEC SEQ AGSNAPSHOT ME F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Table 26 Parameters for the template xsHOOTI Doc Issue Date Page VLT MAN ESO 14650 4942 P97 19 08 2015 128 of 161 ER slt_obs GenericOffset lt allows to decide the sequence of offsets and object or sky observations but with some restrictions concerning the number of exposures per position and exposure times XSHOOTER_slit_obs_GenericOffset Keyword Range Default Value Label in P2PP Free parameters INS OPTI3 NAME see Table 4 1 0x11 UVB slit INS OPTI4 NAME see Table 7 0 9x11 VIS slit INS OPTI5 NAME see Table 8 0 9x11 NIR slit DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXP UVB 0 100 1 UVB number of exposures per offset position SEQ NEXP VIS 0 100 1 VIS number of exposures per offset position SEQ NEXP NIR 0 100 1 NIR number of exposures per offset position SEQ OFFSET COORDS SKY SLIT SKY Offset coordinate type RA DEC or X Y in SEQ RELOFF1 1000 1000 0 List of RA X off
34. In the converging beam coming from the telescope the first element is the telescope entrance shutter Then follows the Calibration Unit that allows to select a choice of flat fielding and wavelength calibration lamps This unit consists of a mechanical structure with calibration lamps an integrating sphere relay optics that simulate the f 13 6 telescope beam and a mirror slide with 3 positions that can be inserted in the telescope beam e one free position for a direct feed from the telescope e one mirror which reflects the light from the integrating sphere equipped with o Wavelength calibration Ar Hg Ne and Xe Penray lamps operating simultaneously o three flat field halogen lamps equipped with different balancing filters to optimize the spectral energy distribution for each arm e one mirror which reflects light from o a wavelength calibration hollow cathode Th Ar lamp o aD lamp for flat fielding the bluest part of the UV Blue spectral range A more detailed description of the functionalities of the calibration system is given in Sect 6 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 20 of 161 2 2 1 2 The Acquisition and Guiding slide Light coming either directly from the telescope or from the Calibration Unit described above reaches first the A amp G slide This structure allows putting into the beam either e aflat45 mirror with 3 positions
35. J and H bands The goal is to offer the possibility of low background observations in the J and H bands to the expense of wavelength coverage i e cutting the K band Note that the normal 0 6 and 0 9 slit with the full wavelength coverage are still offered The blind position can be set if the NIR arm observation is not needed or in case the NIR arm will be highly saturated to do not damage the detector and avoid the remanence It is also used for the measurement of the instrumental background new slits with K band blocking filter ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc Issue Date Page VLT MAN ESO 14650 4942 P97 19 08 2015 41 of 161 With the change of slits the resolving power is slightly different They are indicated in the following table 10 Table 9 NIR spectrograph slits and resolving power slit R old slit wheel R new slit wheel 0 4 11000 10500 0 6 7950 7780 0 6 JH x 7760 0 9 5700 5300 0 9 JH X 5300 1 2 3990 3890 1 5 2540 X 5 1400 IFU 8400 8300 slits with the K band blocking filter Below is the transmission curve of the K band blocking filter Chart Area 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 2000 2020 Transmission of the K band blocking filter 2040 2060 2080 2100 2120 2140 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen
36. Limited Integration in the NIR Added information about ghost spectra Added information about slit ifu position information in acq image header Updated limiting mags with measured NIR sensitivity and background between OH lines in VIS Updated UVB VIS NIR detector parameters Added warning about 2x2 binning mode and inter order bck subtraction 2 1 15 01 2010 Section 5 Templates name changed from SHOOT to XSHOOTER default parameters and hidden parameters Sections 2 4 3 and 3 3 1 plus sparse minor corrections 86 1 09 02 2010 None cmmModule creation ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany 88 89 25 08 2010 26 08 2010 27 02 2011 01 03 2011 03 03 2011 07 03 2011 28 03 2011 20 06 2011 04 08 2011 30 11 2011 Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 4 of 161 All Modified sects 1 3 2 2 1 3 2 2 4 2 2 3 2 2 4 2 4 3 2 4 4 2 4 6 1 2 4 7 3 3 2 3 3 1 3 3 2 3 3 3 3 3 4 4 1 1 5 5 1 5 6 1 5 6 2 5 7 5 9 6 1 3 6 2 3 New Sects 2 4 10 2 4 11 2 4 12 2 4 13 2 4 13 2 4 14 3 4 3 4 1 3 4 2 3 4 3 3 4 4 3 4 5 3 4 6 Modified tables 2 7 11 12 66 New tables 10 13 Modified figures 10 15 New figures 5 11 New subsections 2 4 6 6 1 3 Modified Sections 2 1 2 2 1 4 2 2 42 2 2 4 5 2 3 2 2 4 6 2 4 9 2 4 13 2 4 15 3 4 1 5 1 5 5 5 7 6 1 5 6 2 3 New sections 2 2 4 3 2 4 7 Modified tabl
37. Page 1 5 Reference Documents ram VLT MAN ESO 14650 4942 P97 19 08 2015 14 of 161 X shooter Calibration plan v1 0 XSH PLA ESO 12000 0088 X shooter Templates Reference Manual v0 2 XSH MAN ITA 8000 0031 X shooter technical note about the 11 order vignetting in K band X shooter A amp A article Vernet et al 2011A amp A 536A 105V Report about the non destructive NIR readout mode htt WWW eso org sci facilities paranal instruments xshooter doc reportNDreadoutpublic pdf 6 X shooter imaging mode article Martayan et al 2014 7 Report about the historical wavelength shift between arms Moehler et al 2015 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc Issue Date Page 1 6 Acknowledgements Please if you use XSHOOTER data cite the following articles 1 main article Vernet et al 2011A amp A 536A 105V VLT MAN ESO 14650 4942 P97 19 08 2015 15 of 161 X shooter the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope 2 Forthe flux calibrations Vernet et al 2010HiA 15 535V Building up a database of spectro photometric standards from the UV to the NIR Hamuy et al 1994PASP 106 566H Southern spectrophotometric standards 2 3 For the pipeline and data reduction Modigliani et al 2010SPIE 7737E 56M The X shooter pipeline 4 For the Reflex interface Freudling et al 2013A amp A 559A 96F Automated
38. TemplateType science E added here nodding Template XSHOOTER sit_obs_Stare J XSHOOTER_sIt_obs_FixedSkyOffset XSHOOTER sit_obs_AutoNodOnslit XSHOOTER_ifu_obs_FixedSkyOffset XSHOOTER sIt_obs_GenericOffset XSHOOTER_ifu_obs_Stare XSHOOTER sit_cal_SpecphotNodding v XSHOOTER_sit_acq XSHOOTER_sIt_obs_AutoNodOnslit 1 Get Guide Star from CATALOGUE UVB Slit 1 0x11 RA of guide star 0 VIS Slit 0 9x11 DEC of guide star 0 NIR Slit 0 9x11 Position Angle on Sky 9999 0 UVB Exposure time 5 Offset RA 0 UVB readout mode 100k 1pt hg Offset DEC 0 VIS Exposure time 10 Instrument A amp G Filter B VIS readout mode 100k 1pt hg TCCD Exposure time 1 NIR Exposure time DIT 15 no of NIR sub integrations NDIT 1 Number of exposures for UVB det NE 1 Number of exposures for VIS det NEXP 1 Number of exposures for NIR det NINT 1 Nod throw length arcsec 5 Width of the jitter box arcsec 0 Number of cycles 1 Go to zero offset position at the end Ip ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc Issue Date Page VLT MAN ESO 14650 4942 P97 19 08 2015 69 of 161 Obs Descriptifin Target onstraint Set Time Intervals demonstration Diff RA Diff Dec Proper Motion Dec 0 005000 0 000000 0 000000 rTarget Name target_direct_acquisition Right Ascension 10 00 00 000 Informations of th
39. ThAr spectra are also useful to correct the slight fixed displacement between the 9 pinhole masks and each slit This is also used to monitor the spectral resolution of the different spectrographs Templates to XSHOOTER_s use for these calibrations are t cal UVBVisArcs XSHOOTER slt cal NIRArcs XSHOOTER ifu cal UVBVisArcs XSHOOTER ifu cal UVBVisArcs ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 108 of 161 6 3 Flat field and Wavelength calibrations WARNING ALL EXPOSURE TIMES WILL BE REVISED TO PROVIDE BETTER CALIBRATION FRAMES Flatfield spectra allow to correct for the pixel to pixel variations in detector sensitivity as a function of impinging wavelength of the light and to correct for the structures introduced by imperfections of the slits They also provide a good correction of the blaze function of the For each arm a dedicated halogen lamp with appropriate balancing filters is available to give well exposed flat continuum spectra at all wavelengths within a reasonably short exposure time see Table 17 A deuterium lamp is used for the spectral region shortwards of 350 nm Flatfielding the whole spectral range therefore requires four exposures 2 in UVB 1 in VIS and ON OFF in NIR that have to be taken sequentially Flatfield templates are
40. case the readout of the UVB VIS detectors is performed consecutively one has to sum their readouts and if the NIR arm exposure readout is finished before If the VIS exposure is longer than the UVB exposure UVB readout and the NIR exposure the NIR readout then the execution time will correspond to the VIS exposure the VIS readout time ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 102 of 161 5 1 2 Execution time computation and how to minimize the overheads a Example 1 slit mode UVB VIS arms execution time higher than the NIR one An user defines the observation of a star magnitude 15 in V He uses a direct acquisition He needs for reaching the desired signal to noise ratios exposure times of 100s in UVB 100s in VIS 60s in NIR In such case the overheads are The acquisition and setup overheads XSHOOTER_sit_acg setup 409 10 30 449s acquisition integration times of 1s the overheads coming from the delay of the startup the overheads coming from the readout times The UVB and VIS arms will integrate both during 100s but because they share the same FIERA and that the exposures will be readout sequentially this implies a large dead time The NIR arm exposure will be finished in 60s 1 46s readout it is negligible with respect to the UVB VIS arms times The UVB VIS arms dominate the execution time of the OB If the readou
41. conventions X shooter follows the standard astronomical offset conventions and definitions The positive position angle PA is defined from North to East This is the value that should be entered in the TEL ROT OFFANGLE in all the acquisition templates to set the slit position angle on the sky The fits header keyword HIEARCH ESO ADA POSANG is all X shooter data is minus the position angle of the slit on the sky Note that the value 9999 can be used to set the position angle to the parallactic angle Note also that the parallactic angle is that at the time of the preset acquisition The slit is not maintained at the parallactic angle during the science exposure Offsets are always given in arc seconds but the reference system can be chosen to be the sky Alpha Delta or X shooter slit coordinate system X Y Offset conventions are illustrated below Templates use cumulative offsets the position at a given time is derived from the sum of all offsets specified so far in the template For example the series of offsets 0 10 0 10 brings the telescope back to the original position for the last exposure This example could have been for instance the definition of a series in which we define an exposure on object followed by two sky exposures at 10 of the original position before pointing back on the object for the fourth exposure Other example of series of offsets offset A RA 10 DEC 0 offset B RA 0 DEC 10
42. data reduction workflows for astronomy The ESO Reflex environment 5 For the imaging mode Martayan et al The Messenger 156 June 2014 The X shooter Imaging Mode 1 7 Contact In case of instrument related questions use xshooter eso org In case of phase1 2 related questions use usd_xshooter eso org or usd help eso or ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 16 of 161 1 3 News in P96 a new ETC is available using the image quality on the instrument instrument telescope sky contributions instead of the seeing However the seeing is still used as input in V band at the zenith There is not yet a new sky model available for XSHOOTER and the NIR background is underestimated in K band Since P94 XSHOOTER is available again at UT2 In P93 as in P92 XSHOOTER will be available at UT3 instead of UT2 This would allow decreasing a bit the pressure factor on this instrument In P93 is introduced the light imaging mode of XSHOOTER performed with the acquisition and guiding camera At the same time only a single snapshot is taken of the last image during the acquisition loop 2 in case of blind offset before and after the blind offset More details will come in a dedicated document Note in P92 some tests were started of a new mode that allows observing very bright objects even negative magnitudes Once the tests completed th
43. exposures Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode INS OPTI5 NAME see Table 8 Pin_0 5 NIR Slit slide Arcs multi pinhole 2d wave maps wavelength calibration Table 63 User and fixed keywords for XSHOOT ER slt cal UVBVisArcsMultiplePinhole XSHOOTER_sit_cal_UVBVisArcsMultiplePinhole Free Parameters Keyword Range Default Value Label in P2PP DET1 WIN1 UIT1 0 36000 15 UVB exposure time DET1 READ CLKDESCR see Table 5 400k 1pt lg UVB readout mode DET2 WIN1 UIT1 0 36000 10 VIS exposure time DET2 READ CLKDESCR see Table 5 400k 1pt lg VIS readout mode SEQ NEXPO UVB 0 100 1 UVB No of exposure SEQ NEXPO VIS 0 100 1 VIS No of exposure Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode INS OPTI3 NAME see Table 4 Pin_row UVB Slit slide INS OPTI4 NAME see Table 7 Pin_row VIS Slit slide Table 64 User and fixed keywords for XSHOOT ER slt cal NIRArcsMultiplePinhole XSHOOTER_slt_cal_NIRArcsMultiplePinhole Keyword Range Default Value Label in P2PP DET3 DIT 0 36000 5 NIR exposure time DET3 NDIT 1 20 10 Number of DITs SEQ NEXPO 0 100 1 NIR No of exposures Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode INS OPTI5 NAME see Table 8 Pin_row NIR Slit wheel ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany
44. exposures in object sky and a proper automatic data reduction by the pipeline ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany 7 1 6 Night time Calibration Templates Spectro photometric Standard Stars Table 31 User and fixed keywords for XSHOOT Doc Issue Date Page VLT MAN ESO 14650 4942 P97 19 08 2015 132 of 161 ER slt_cal SpecphotStdStare The template is identical to that for slit observation in stare mode except for some of the default parameters XSHOOTER_slit_cal_SpecphotStdStare Keyword Range Default Value Label in P2PP Free parameters INS OPTI3 NAME see Table 4 5 0x11 UVB slit INS OPTI4 NAME see Table 7 5 0x11 VIS slit INS OPTI5 NAME see Table 8 5 0x11 NIR slit DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXPO UVB 0 100 1 UVB number of exposures SEQ NEXPO VIS 0 100 1 VIS number of exposures SEQ NEXPO NIR 0 100 1 NIR number of exposures Fixed Values INS MODE SLITSPEC SLITSPEC Instrument Mode IFUSPEC SEQ AGSNAPSHOT TF F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany
45. filter 1238nm veers reereee with filter 1300nm without filter 1300nm s with filter 1682nm without filter 1682nm ssssseneceee gi b oO 1 10 100 1000 DIT s ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 47 of 161 2 2 6 4 Optical layout detector lenses Figure 8 The NIR spectrograph optical layout The optical layout of the NIR spectrograph is presented in Figure 8 The conceptual design is the same than for the UVB and the VIS spectrographs Light entering the spectrograph via the entrance slit and folding mirror M5 feeds an off axis Maksutov inspired collimator In this case the collimator is made of 2 spherical mirrors M6 and M7 plus an Infrasil corrector lens with only spherical surfaces In order to get enough cross dispersion three prisms are used in double path Prism 1 is a 35 top angle made of Infrasil prisms 2 and 3 are two 22 top angle ZnSe prisms This design provides an almost constant order separation Main dispersion is provided by a 55 grooves mm chelle grating with a blaze angle of 46 07 The off blaze angle is 0 0 while the off plane angle is 1 8 After dispersion the collimator creates an intermediate spectrum near the entrance slit where M8 a spherical mirror acts as a field mirror relocating the pupil between L2 and L3 the last lenses of the camera The fixed focus cam
46. is XSHOOTER slt_cal UvbVisArcsMultiplePinhole and XSHOOTER slt cal NIRArcsMultiplePinhole gt em oe arene ome Cad Se eee ose hea rey te dy MEY o_o eme peia gnt a 665000 amp eae r NN ou Sess oe fe ease on om ver Bene ome Let A aay ent o bocom lt sa a Hape need gt o Oebes Oe 0 it Be as ron nm ess gt bd wi io e eee 7o gt m 3 ei u eee o ome 4 ri pro gt eee a ama oe G p gt gt pon eee a e esa Doz ER lt oe b 2 eere ER AAPM ii eee ae o 068 RSA EIEN BM S gA ps on dor eee x se e ag bs posi ee8 e u e ss ef aan 0 rr errit t eerst aan anne r rt ara nennen seoseeveet nnnnnentt eeeegeer RATEN prestre Figure 18 portion of a 9 pinhole ThAr VIS frame used for wavelength and spatial scale calibration The accuracy of the wavelength calibration typically achieved using the X shooter Data Reduction Software is better than 2km s over the whole wavelength range see section 2 4 9 In this process the quality of the list of lines used to perform the calibration is critical in particular it has to be carefully cleaned from blends Such a ThAr line list is provided together with the X shooter Data Reduction Software package Full slit
47. middle of the atmospheric dispersion range for the NIR arm This means that this wavelength is kept at the center of the NIR slit At a zenithal distance of 60 the length of the spectrum dispersed by the atmosphere is 0 35 so the extremes of the spectrum can be displaced with respect to the center of the slit by up to 0 175 If measurement of absolute flux is an important issue the slit should then be placed at parallactic angle ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 26 of 161 2 2 2 ADCs problems and disabled ADCs observing mode in SLIT and IFU During March to July 2012 the ADCs atmospheric dispersion correctors for the UVB and VIS arms in X shooter have been occasionally failing Unfortunately the rate of such failures has increased until being daily leading sometimes to data taken in sub optimal instrument configuration which needs to be taken into account when reducing and analyzing such observations There is an ongoing investigation to find the cause for the ADCs misbehavior but it is unlikely that the situation is back to normal for the next few months Incorrect position of ADCs might lead to slit losses worse than if they are not used Consequently the ADCs were temporarily disabled set at the non deviation position as in the IFU mode on August 1st A major intervention to fix the problem is currently under investigation
48. mirror o acquisition and imaging send the full 1 5 x1 5 field of view to the A amp G camera This is the position used during all acquisition sequences o spectroscopic observations and monitoring a slot lets the central 10 x15 of the field go through to the spectrographs while reflecting the peripheral field to the A amp G camera This is the position used for all science observations o artificial star a 0 5 pinhole used for optical alignment and engineering purposes e the IFU described in Sect 2 2 1 3 e a 50 50 pellicle beam splitter at 45 which is to used look down into the instrument with the A amp G camera and is exclusively used for engineering purposes ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 21 of 161 2 2 1 3 The IFU Telescope bie IFU fy Figure 4 Top view of the effect of the IFU The central field is directly transmitted to form the central slitlet green while the each lateral field in blue and red are reflected toward a pair of spherical mirrors and realigned at the end of the central slice to form the exit slit Bottom The field before left and after the IFU right The IFU acts such that the lateral fields seem to rotate around a corner of their small edge The two white slots are not real gaps but just guides to help visualize the top and the bottom of each slice in the drawing
49. object radial velocity map structure or other IFU In case you want to investigate the structure of an extended object such as a nebula to do the radial velocity mapping of a galaxy etc the use of the IFU is recommended e Time series of variable object The observing mode SYNCHONIZED was foreseen for such kind of observations It synchronizes the three arms at the middle of their exposures This template can be used for following spectroscopic binaries The readout time should be chosen as small as possible i e here the 400KHz mode should be preferred to the 100kKHz mode for the UVB and VIS mode However it depends on the target too timescale of the variation faintness e Highly time critical object fast flux variation GRBs etc RRM In case you want to observe objects visible during few minutes or hours such as Gamma Ray Bursts the Rapid Response Mode is appropriate Just follow the same strategy than indicated above and instead of the normal acquisition template you will use the RRM acquisition template ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 82 of 161 e Imaging mode In P93 the imaging mode of XSHOOTER will be offered It has to be combined to slit or IFU observations for science OBs The structure of the OB could be like this Slit acquisition stare imaging template1 with filter V 4 exposures of 2s stare imaging
50. range gives the min max values of the ratio and the standard deviation std is given Stare mode AM 1 8 With ADCs ratio perpendicular parallactic Arm Average range std UVB 0 88 0 85 0 92 0 01 VIS 0 94 0 92 0 97 0 01 c Comparison of observations with without ADCs There are 2 sets of measurements comparing the efficiency of observations with without the ADCs for the slit angle at parallactic angle or perpendicular to it One in stare mode at airmass 1 8 that can be compared to the subsection b One in nodding mode at airmass 1 35 Stare mode AM 1 8 Ratios no ADCs with ADCs Arm slit angle Average range std UVB parallactic 0 88 0 46 1 0 0 12 UVB perpendicular 0 46 0 10 1 0 0 33 VIS parallactic 0 92 0 86 1 0 0 03 VIS perpendicular 0 77 0 47 1 0 0 18 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 29 of 161 Nodding mode AM 1 35 Ratios no ADCs with ADCs Arm slit angle Average range std UVB parallactic 0 87 0 87 0 9 0 01 UVB perpendicular 0 82 0 56 1 0 0 15 VIS parallactic 0 88 0 82 0 9 0 02 VIS perpendicular 0 81 0 66 0 99 0 11 The measurements were performed on short integration times and if possible in stable conditions of the seeing d Efficiency of observations without ADCs at different given slit angles and airmasses
51. target as well as the science target must be clearly indicated on the finding chart It is important to note that the offsets in all templates are offsets on sky as in other Paranal instruments They are computed as follows the offset RA corresponds to delta RA xcos DEC and the offset DEC is the difference delta DEC It is also important to take into account the proper motions of the objects For the reference acquisition star it has to be directly in BOB pmra and pmdec parameters Moreover it is necessary for the blind offsets between the acquisition star and the target to take into account the proper motions of both objects in the computation of the offsets The accuracy of the blind offset is better than a few mas However if the offset is very large much larger than the fov of the Cassegrain focus of few arcmins then the telescope operator may have to choose another VLT guide star which could introduce an offset in the coordinates and positioning depending on the quality of the guide star coordinates Note the VLT guide star in the acquisition template should not be confused with the reference star for the blind offset Usually the guide star is taken from a catalogue and the coordinates can be set to 0 in the OB this is true for direct and blind offset acquisition ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 670of161
52. that nodding is not offered in IFU mode because the field of view 4 x1 8 is too small to nod within the IFU Also note that it is not possible to move the target in one arm independently from the other arms 4 5 i i Jitter box 1 jitter box 8 A u Nod throw i Acquisition 4 nodding box position 2 3 6 7 B Slit broadened Figure 17 conventions used for nodding of 4 along slit observations The sequence illustrated here corresponds to 4 cycles 8 exposures ABBAABBA with a jitter box of 1 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 78 of 161 3 4 5 Fixed offset to sky SLIT and IFU When observing extended objects for which there is no or not enough pure sky in the 11 slit to perform a good sky subtraction one should use the template XSHOOTER slt_obs FixedSkyOffset or XSHOOTER ifu obs FixedSkyOffset It allows alternating between an object O and sky position S with the possibility of adding a small jittering around the object and the sky position One cycle is a pair of OS or SO observations Cycles are repeated in OSSO sequences For each arm the user chooses the number of exposures taken at each position and the exposure time both identical for all O and S positions Exposures are asynchronous It is important to note that the offsets in all templates are offsets on sky as in other Paranal instruments Th
53. the first optical elements encountered by the science light The first dichroic at an incidence angle of 15 reflects more than 98 of the light between 350 and 543 nm and transmits 95 of the light between 600 and 2300 nm The second dichroic also at 15 incidence has a reflectivity above 98 between 535 nm and 985 nm and transmits more than 96 of the light between 1045 and 2300 nm The combined efficiency of the two dichroics is shown in Fig 6 it is well above 90 over most of the spectral range 2 2 1 6 The flexure compensation tip tilt mirrors Light reflected and or transmitted by the two dichroics reaches in each arm a folding mirror mounted on piezo tip tilt mount These mirrors are used to fold the beam and correct for backbone flexure to keep the relative alignment of the three spectrograph slits within less than 0 02 at any position of the instrument They also compensate for shifts due to atmospheric differential refraction between the telescope tracking wavelength fixed at 470 nm for all SLIT X shooter observations and the undeviated wavelength of the two ADCs for Efficiency 300 800 1300 1800 2300 Wavelength nm Figure 6 The combined efficiency of the two dichroic beam splitters In blue reflection on dichroic 1 in orange transmission through dichroic 1 and reflection on dichroic 2 in red transmission through dichroics 1 amp 2 UVB and VIS arms and the middle
54. 000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXP UVB 0 100 1 UVB number of exposures per offset position SEQ NEXP VIS 0 100 1 VIS number of exposure per offset position SEQ NEXP NIR 0 100 1 NIR number of exposure per offset position SEQ FIXOFF RA 100 100 0 RA fixed offset arcsec SEQ FIXOFF DEC 100 100 0 DEC fixed offset arcsec SEQ JITTER WIDTH 0 2 0 Jitter box width in arcsec SEQ NABCYCLES 0 100 1 Number OS or SO cycles SEQ OFFSET ZERO TE T Return to Origin Fixed Values INS MODE IFUSPEC SLITSPEC IFUSPEC Instrument Mode INS OPTI3 NAME see Table 4 1x12 6 UVB slit INS OPTI4 NAME see Table 7 1x12 6 VIS slit INS OPTI5 NAME see Table 8 1x12 6 NIR slit SEQ AGSNAPSHOT mE F Take an acquisition image before science exposures Attached night calibrations must be taken after a science template Table 40 Parameters for the template XSHOOT ER slt cal UVBVISArcAtt XSHOOTER _sit_cal_UVBVisArcsAtt Keyword Range Default Value Label in P2PP Free Parameters DET1 WIN1 UIT1 0 36000 UVB exposure time DET1 READ CLKDESCR see Table 5 400 1pt lg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time DET2 READ CLKDESCR see Table 5 400 1pt lg VIS readout mode SEQ NEXPO UVB 0 100 1 No of UVB exposures SEQ NEXPO VIS 0 100 1 No of VIS exposures Fixed Value INS MODE IFUSPEC SLITSPEC SLITSPEC Instrume
55. 04 6 2 Wavelength and spatial scale Calibration ccccecececceceeeee eee e eter eeeeeeeeeeeeeeeeeeees 107 6 3 Flat field and Wavelength calibrations cccccccceceeeeeeeeeeeeeeeeeneeeeeeeeeeeeeenaaees 108 6 4 Spectroscopic SKVIIAIS an ende 109 6 5 Attached Calibrations cccccccsceeeeeeceeeeceeeaeeeceeeeeeeeeeeaaaeaaeeeeeeeeeeaaaaaaeeeeeeeeeeeaaaa 110 6 6 Spectrophotometric Calibration cccccceceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeseeeeeeeeeeeeeseseeees 110 6 6 1 Telluric absorption correction 0 ccccceeeeeeeeaeeeeeeeeeeeeeeeaaeeceeeeeeeeeeeaaeaeees 110 6 6 2 Absolute flux Calibration cccccccccccccccceceeceeeeeeeeeeceeeeeeeeeeeeeeeeeeeseeeeeeeseeenes 112 6 7 The X shooter pipeline sosssssssssnnnennnnnnnnnnnnnnnnennnnnnennnnnnnnensnnnnrenn 113 6 8 Examples of observations with X SHOOtEl cccccccccccccceceeeeeeeeeeeeeeeeeeeeeeeeeeeeess 114 6 9 Frequently Asked Questions su 114 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany T Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 10 of 161 Reference material sen ee seele 7 1 Templates reference ccccccccccccccceeceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeneeegs 7 1 1 7 1 2 7 1 3 Sli Orientation and conventions ueennnnnnnnnnnnnnnnnnnnnnnnnnnennnennn nn Examples of position angles and offsets ccccccccccccccc
56. 0IE Cooling system Pelletier QE 82 at 580 nm 50 at 380 nm and 820 nm Number of pixels 562x528 Pixel size 13umx13um 0 1744 0 0016 since P92 at UT3 1 5 x1 5 but filters do not cover the corners Gain e ADU 1 29 0 02 Readout noise e rms 4 14 0 08 Saturation ADU 65535 Readout mode and overheads Fast readout mode only Wipe time 0 01 s readout time 0 33 s transfer time 0 78 s total time 1 12 s Dark current level ADU pixel h 0 97 exposure time of 10s Fringing amplitude Depends on the filters 2to4 inl z Non linearity ADU lt 1 at 10000 and 50000 ADUs Bias level ADU 1688 5 5 Prescan and overscan areas X 1 26 and 538 562 Y 1 15 and 528 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 87of 161 Figure 2bis A amp G CCD quantum efficiency curve A amp G Camera CCD T T 400 600 800 Wavelength nm The A amp G CCD cooling system produces small oscillations of the CCD temperature Temperature variations affect the dark current level In case of short exposure times when the image sampling frequency corresponds to the frequency of the temperature oscillations this leads to beats and background level variations from one image to the next These variations in background level disappear if a longer exposure time is selec
57. 1 hour exposure Other parameters air mass 1 2 0 8 seeing 3 days from new moon 1 slit for UVB 0 9 slit for VIS and NIR The ESO ETC was used to compute these values The model uses overall efficiencies measured during commissioning Note that these performance estimates assume no degradation of the SNR in the extraction process or in the sky subtraction The decrease in efficiency to the blue side of the UVB range is due to the atmospheric absorption at the red side of the VIS band it is due to the decrease in efficiency of the CCD while on the long wavelength side of the NIR range it is due to the rise of the thermal background ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 54 of 161 UVBarm VIS arm NIR arm wavelength magnitude wavelength magnitude wavelength magnitude 556 20 5 1001 6 18 1 2377 28 15 5 531 21 957 3 19 3 2179 17 16 8 496 8 21 3 904 3 19 9 2011 54 16 8 466 4 21 4 860 2 19 8 1867 86 16 6 438 8 21 4 815 8 20 1743 33 19 414 5 21 4 777 6 20 1 1634 38 19 1 393 2 21 742 6 20 2 1538 23 19 2 373 5 20 711 2 20 2 1452 78 19 356 1 19 5 682 1 20 3 1376 31 18 339 8 19 2 653 8 20 1 1307 5 19 4 325 19 629 5 22 1245 24 19 5 312 2 18 607 7 2 1188 64 19 6 585 9 22 1136 96 19 2 568 20 2 1089 58 19 6 550 5 18 5 1046 19 6 1005 77 18 7 Table giving the limiting magn
58. 14 to 70 8 pixels 0 155 pix at order 24 e VIS 65 9 pixels 0 167 pix at order 17 to 72 0 pixels 0 153 pix at order 30 e NIR 52 4 pixels 0 21 pix at order 11 to 59 9 pixels 0 184 pix at order 26 The minimum separation between orders is 4 unbinned pixels to allow inter order background evaluation The dichroic crossover region between UVB VIS and VIS NIR is at 559 5 nm and 1024 nm respectively e Between UVB and VIS the region where the combined dichroics transmit less than 80 is 556 0 563 8 nm 7 8 nm wide This region falls in the UVB order 13 see Figure 11 and VIS order 29 Note that the VIS order 30 will still get some flux since dichroics still reflect transmit 15 of the light at 550nm Figure 11 SLIT UVB QTH flat field UVB arm the dip due to the first dichroic is easily visible in the top order e Between VIS and NIR the combined dichroics transmit less than 80 of the light between 1009 5 1035 nm 35 5 nm wide This transition region falls in the VIS order 16 and NIR orders 26 and 25 There is an oscillation of this dichroic dip in both the UVB and VIS arms The location of the edge and hence the instrumental response in these ranges is affected by environmental influences humidity temperature Flat fielding difficulties have been noticed especially in the UVB arm beyond 556 nm ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc Issue Date Page
59. 2 3 2 Spectral resolution and sampling The user can only affect the spectral resolution through the choice of slit width and to some extent with the binning in UVB and VIS The resolution and pixel sampling without binning as a function of the slit width is given in Table 12 Table 12 Resolution as a function of slit width VLT MAN ESO 14650 4942 P97 19 08 2015 52 of 161 UVB VIS NIR Slit R Sampling Slit R Sampling Slit R Sampling width MAX pix FWHM width A AA pix FWHM width A AX _ pix FWHM 0 5 9100 3 5 0 4 17400 3 0 0 4 10500 2 2 0 8 6200 5 2 0 7 11000 4 8 0 6 7770 29 1 0 5100 6 3 0 9 8800 6 0 0 9 5300 4 2 1 3 4000 8 1 1 2 6700 7 9 1 2 3900 5 8 1 6 3300 9 9 15 5400 9 7 IFU 7900 4 1 IFU 12600 4 2 IFU 8300 2 7 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 53 of 161 2 3 3 Overall sensitivity The total efficiency has been measured on sky using several standard stars observed during commissioning Based on these values the expected limiting AB magnitudes at blaze in 1 hour for a S N of 10 per spectral bin are given in Figure 12 Please note that a binning 2x1 is used while there is no possibility to bin in the NIR arm One can also refer to the table below with no binning Figure 12 Limiting AB magnitude of X shooter per spectral bin using 2 pixels binning in the spectral direction at S N 10 in a
60. 2 WIN1 UIT1 DET2 READ CLKDESCR SEQ NEXPO UVB SEQ NEXPO VIS INS MODE INS OPTI3 NAME INS OPTI4 NAME EEHOOTER ail al Are Free Parameters Range Default Value Label in P2PP 0 36000 UVB exposure time see Table 6 400k 1pt lg UVB readout mode 0 36000 VIS exposure time see Table 6 400k 1pt lg VIS readout mode 0 100 UVB No of exposure 0 100 VIS No of exposure Fixed Value SLITSPEC IFUSPEC SLITSPEC Instrument Mode see Table 5 Pin row UVB Slit slide see Table 8 Pin row VIS Slit slide ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 144 of 161 Table 50 User and fixed keywords for XSHOOTER slt cal NIRArcsMultiplePinhole XSHOOTER slt_cal_NIRArcsMultiplePinhole DET3 DIT NIR exposure time DET3 NDIT Number of DITs 1 SEQ NEXPO 0 100 Rn NIR No of exposures Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode INS OPTI5 NAME see Table 9 NIR Slit wheel ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 145 of 161 7 1 7 Daytime Calibration templates Slit and IFU arc lamp calibrations resolution tilt Table 48 User and fixed keywords for XSHOOT ER slt cal UVBVisArcs XSHOOTER_sit_cal_UVBVisArcs Keyword Range Default Value Label
61. 24 19 TEED BAUS nannten 63 Observing with ice LM Cas ee ee 64 3 1 Observing modes and basic ChOiC S ccceeeeeeeeeeeeeeeeeeeeeeeeeeeeaaeeeeeeeeeneeees 64 3 2 Target ACQUISIION idctsccasicavcecvccntienscshencctnsd ne 65 3 2 1 Acquisition loop eee 65 3 2 2 Blind offset precisions nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nn 66 3 3 Examples of OBs preparations acquisitions With P2pp3 cccccccceeeeeeeeeeeeeeeees 67 3 3 1 Direct acquisition 40sssnsssnnnnnnnnennnnnnnnnnnnnnnnnnnnnnnnnnnnnnnennnnnnrrnnnnnnnen 67 3 3 2 Blind offset acquisition unennnennnnnnnnnnnnnnnnnnnnnnnnnnnn nn 73 3 4 Spectroscopic observations ccccceceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeegs 75 3 4 1 Overview and important remarkS eseeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeseeeeeees 75 3 4 1 1 Observing modes 2 2 cczsciedaresdeocercaatonsrenccetgreadtensienewpestadteaimacesmneadiangieia eae 75 3 4 1 2 Effect of atmospheric diSPersiOn cccccccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeseeeeeeeeeeees 75 3 4 1 3 Exposure time in the NIR arm cccccceccceeec cece eeeeeeeeeeeeeeeaaaeaaeeeeeeeeseeaaaaaees 75 3 4 2 Staring SLIT and IFU u a 76 3 4 3 Staring synchronized SLIT and IFU cccceeeeeeeeeeeeeeeeneeeeeeeeeeeeeeeeneeeeeeees 76 3 4 4 Nodding along the slit SLIT Only eeecceeseeeeeeeeeeeeeeenneeeeeeeeeeeeeeeenaeeeeeeers
62. 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXP UVB 0 100 1 UVB number of exposures SEQ NEXP VIS 0 100 1 VIS number of exposures SEQ NEXP NIR 0 100 1 NIR number of exposures Fixed Values INS MODE IFUSPEC SLITSPEC IFUSPEC Instrument Mode INS OPTI3 NAME see Table 4 1x12 6 UVB slit INS OPTI4 NAME see Table 7 1x12 6 VIS slit INS OPTI5 NAME see Table 8 1x12 6 NIR slit SEQ AGSNAPSHOT T F F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Table 39 User defined and fixed parameters for SHOOT ifu_cal_TelluricStdOffset template is identical to XSHOOTER_ifu_obs FixedSkyOffset Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 140 of 161 The Be careful the offsets in RA and DEC are setup by default to 1 XSHOOTER _ifu_cal_TelluricStdOffset Keyword Range Default Value Label in P2PP Free parameters DET1 WIN1 UIT1 0 36000 UVB Exposure Time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB read out mode DET2 WIN1 UIT1 0 36000 VIS Exposure Time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS read out mode DET3 DIT 0 36
63. 4 NAME INS OPTI5 NAME 100k 1pt hg 100k 1pt hg 2x2 400k 1pt lg 1x2 400k Ipt ig 0 36000 30 0 36000 20 100k 1pt hg 100k 1pt hg 2x2 400k 1pt Ig 1x2 400k Ipt g 0 36000 60 0 36000 20 1 20 J CALIB 100k Ipt hg 1x2 400k Ipt lg 400k 1pt lg 2x2 100k 1pt hg 1x2 400k Ipt lg 400k 1pt lg 2x2 ECHELLE MULTI PINHOLE LAMP ORDERDEF 0 100 2 0 100 2 0 500 2 0 500 1 UVB readout mode UVB Exposure time High Flat UVB Exposure time Low Flat VIS readout mode VIS Exposure time NIR Exposure time DIT no of NIR sub integrations NDIT Data Prod Cath Data Prod Tech Data Prod Type Number of exposures High Flat Number of exposures Low Flat Number of exposures for NIR det NINT Number of exposures for VIS det ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 153 of 161 Table 70 Template for taking detector FF and biases for the linearity measurements of the detectors XSHOOTER_gen_cal_CCDFlat tsf To be specified Hidden Range Default DET1 READ CLKDESCR 100k 1pt hg 100k 1pthg 1x2 U DET1 WIN1 UIT1 DET2 READ CLKDESCR DET2 WIN1 UIT1 SEQ NEXPO UVB SEQ NEXPO VIS Fixed values 100k 1pt hg 2x2 400k 1pt lg 400k Ipt lg Ix2 400k lpt lg 2x2 100k Ipt hg 0 36000 7 UVB Exposure time 100k 1pt hg 100k 1pt hg 1x2 VIS readout mode 100k 1pt hg 2x2 400k 1pt lg
64. 400k Ipt lg Ix2 400k 1pt lg 2x2 100k Ipt hg 0 36000 7 VIS Exposure time 0 500 1 Number of exposures for UVB det NEXP 0 500 1 Number of exposures for VIS det EXP Taba ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 154 of 161 7 1 8 Imaging mode templates manual a Approved template combinations VM only XSHOOTER_img_acq XSHOOTER_img_obs XSHOOTER_img_obs_GenericOffset SM XSHOOTER_img_acq XSHOOTER_img_cal_phot and or XSHOOTER_img_cal_dist XSHOOTER_sit_acq 1 SLT science or std template Possibility to add XSHOOTER_img_obs XSHOOTER_img_obs_GenericOffset XSHOOTER_img_cal_phot XSHOOTER_img_cal_dist XSHOOTER_ifu_acq 1 IFU science or std template Possibility to add XSHOOTER_img_obs XSHOOTER_img_obs_GenericOffset XSHOOTER_img_cal_phot XSHOOTER_img_cal_dist XSHOOTER_img_acq_FlatSky tsf imaging skyflats templates Possibility to add XSHOOTER_img_cal_Flat tsf ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 155 of 161 b Template description NIGHTIME IMAGING TEMPLATES Imaging acquisition template also allows blind offset XSHOOTER_img_acq tsf To be specified Parameter Piden Range Default label SS DET4 WIN1 UITI no 0 36000 7 TCCD Exposure time DPR CA
65. 45 degrees it is just needed to enter 45 degrees in the acquisition template If the user needs a position angle of 315 degrees it is needed to enter in the acquisition template an angle of 45 degrees 315 360 The convention is to use angles from 0 to 180 degrees and from 0 to 180 degrees IR as N PA 0 degree PA 45 degrees PA 45 or 315 degrees ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 119 of 161 i Examples of offsets As indicated a positive offset in the x or y direction will move the object in direction of x and y axis The first example with PA 0 degree shows the results of a positive offset in x The object star moves in the direction of the x axis and the slit moves in the axis The x y axis are attached to the slit gt Y The second offset with PA 45 degrees shows a positive offset in y axis The Moon goes to the upper right corner movement in y axis while the slit moves in the lower left corner reverse movement in the y axis ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 120 of 161 It is important to note that the offsets in all templates are offsets on sky as in other Paranal instruments They are computed as follows offset RA delta RA xcos DEC and offset DEC delta
66. 45 parall 0 31 0 05 0 64 0 20 UVB 2 20 90 parall 0 18 0 04 0 23 0 06 VIS 1 10 45 parall 0 87 0 83 0 94 0 03 VIS 1 10 90 parall 0 80 0 75 0 92 0 04 VIS 1 51 45 parall 0 92 0 87 1 0 0 04 VIS 1 51 90 parall 0 72 0 47 1 0 0 17 VIS 2 20 45 parall 0 63 0 37 0 83 0 16 VIS 2 20 90 parall 0 31 0 28 0 34 0 02 e Efficiency of observations without ADCs at given airmass and slit angle but with different tracking wavelength Up to now only in IFU mode the user can choose the tracking wavelength This option will be considered for the SLIT mode as well In the following tables we compare the flux ratios other the orders for the observations at 470nm default tracking wavelength with respect to the observation at another wavelength The observations were performed without ADCs in nodding mode at AM 1 35 e f the user chooses the tracking wavelength equals to 600nm instead of 470nm F470 F600 Arm Average range std UVB 0 96 0 66 1 47 0 25 VIS 0 85 0 74 1 00 0 09 For the UVB arm the ratio is higher in blue orders 1 4 with the 470nm tracking wavelength and lower in the red orders 0 7 compared to the 600nm tracking wavelength This is the same evolution for the VIS arm e Same measurements but with the tracking wavelength at 850nm instead of 470nm F470 F850 Arm Average range std UVB 1 04 0 54 1 89 0 45 VIS 0 79 0 62 1 08 0 14 For the UVB arm the ratio is higher
67. 5 of 161 3 2 Target acquisition 3 2 1 Acquisition loop Target acquisition for SLIT and IFU modes is almost identical The main steps of a typical acquisition sequence are the following 1 2 3 10 11 Warmup of the lamp for the flexure correction measurement Preset the telescope to the target coordinates and set the adaptor rotator to the chosen position angle UVB and VIS ADCs start tracking to compensate for atmospheric dispersion in SLIT mode or set to their OFF position i e at minimum deviation in IFU mode Cross correlating two frames of arc lamp spectra measures backbone flexure The first frame corresponds to an arc lamp spectrum taken with the Acquisition and Guiding slide 0 5 pinhole with the 5 slit in each arm The second frame is an arc spectrum taken with the 0 5 pinhole present in each slit slide arm and the slot position in the Acquisition and Guiding camera Commands are sent to the three tip tilt mirrors based on computed flexures If necessary this process is re iterated The Acquisition and Guiding slide is set to MIR position the field is now visible in the acquisition camera and an acquisition image can be acquired The spectroscopic target is identified or the reference object in case of blind offset and its coordinates on the detector are determined by a centring algorithm The telescope is offset to the reference pixel on the detector corresponding to the position of the image the
68. 8 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 147 of 161 Table 53 User and fixed keywords for XSHOOTER slt cal VISLampFlat XSHOOTER _slit_cal_ViSLampFlat Free Parameters Keyword Range Default Value Label in P2PP INS OPTI4 NAME see Table 4 0 9x11 VIS slit DET2 WIN1 UIT1 0 36000 8 VIS Exposure Time DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode SEQ NEXPO 0 100 5 VIS of exposure Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode Table 54 User and fixed keywords for XSHOOTER slt cal NIRLampFlat XSHOOTER_slit_cal_NIRLampFlat Free Parameters Keyword Range Default Value Label in P2PP INS OPTI5 NAME see Table 8 0 9x11 NIR slit DET3 DIT 0 36000 40 NIR exposure time DET3 NDIT 1 20 1 Number of DITs SEQ NEXPO 0 100 5 NIR No of exposure Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode Table 55 User and fixed keywords for XSHOOTER ifu cal UBVLampFlat XSHOOTER_ifu_cal_UVBLampFlat Free Parameters Keyword Range Default Value Label in P2PP DET1 READ CLKDESCR_ see Table 5 100k 1pt hg UVB readout mode DET1 WIN1 UIT1 HIGHF 0 36000 12 3 Halo lamp exposure time DET1 WIN1 UIT1 LOWF 0 36000 4 7 D lamp exposure time SEQ NEXPO HIGHF 0 100 5 Numb
69. 942 Issue P97 Date 19 08 2015 Page 106 of 161 Table 16 long term calibration plan Calibration UVB frames VIS frames f NIR Frequency Purpose rames DARK_UVB_ 100k 3x1hour monthly dark DARK_UVB_400k 3x1hour monthly dark DARK_VIS_ 100k 3x1hour monthly dark DARK_VIS_400k 3x1hour monthly dark DARK_UVB_100k_1x2 3x1hour monthly dark DARK_UVB_400k_1x2 3x1hour monthly dark DARK_VIS_100k_1x2 3x1hour monthly dark DARK_VIS_400k_1x2 3x1hour monthly dark DARK_UVB_100k_2x2 3x1hour 2 months dark DARK_UVB_400k_2x2 3x1hour 2 months dark DARK_VIS_100k_2x2 3x1hour 2 months dark DARK_VIS_400k_2x2 3x1hour 2 months dark Long darks NIR 3x1hour Du dark request Set of detector AR LINEARITY_UVB_100k FF biases monthly detector monitoring Set of detector P LINEARITY_UVB_400k FE biases monthly detector monitoring Set of detector P LINEARITY_VIS_100k FE biases monthly detector monitoring Set of detector T LINEARITY_VIS_400k FF biases monthly detector monitoring LINEARITY_UVB_100k_1x2 Set of detector monthly detector monitoring LINEARITY_UVB_400k_1x2 Setof AA monthly detector monitoring Set of detector 4s LINEARITY_VIS_100k_1x2 FF biases monthly detector monitoring Set of detector A LINEARITY_VIS_400k_1x2 FF biases monthly detector monitoring Set of detector a LINEARITY_UVB_100k_2x2 FF biases monthly detector monitoring Set of detector T LINEARITY_UVB_400k_2x2 FF bi ses monthly detector monitoring Set of detector a LINEARITY_VIS_100k_2x2 FF bi
70. AN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 23 of 161 2 2 1 4 The Acquisition and Guiding Camera The A amp G camera allows to visually detecting and center objects from the U to the z band This unit consists in e a filter wheel equipped with a full UBVRI Johnson filter set and a full Sloan Digital Sky Survey SDDS filter set Transmission curves are provided in Section 4 e a Pelletier cooled 13 um pixel 512x512 E2V broad band coated Technical CCD57 10 onto which the focal plane is re imaged at f 1 91 through a focal reducer This setup provides a plate scale of 0 173 pix and a field of view of 1 47 x1 47 The QE curve of the detector is provided in Section 4 This acquisition device that can also be used to record images of the target field through different filters provides a good enough sampling to centroid targets to lt 0 1 accuracy in all seeing conditions The noise of the technical CCD is currently of RON of 4 1e The limiting magnitudes for a direct acquisition were measured for different filters under relatively bad conditions thin cirrus full Moon seeing about 0 7 see Table 3 Table 3 Limiting magnitudes for a direct acquisition U B V R 22 22 22 5 22 5 22 5 30s 30s 20s 20s 20s We still have to measure their limiting magnitudes under clear conditions and in dark time However in case of worse weather the limiting magnitudes are smaller We still recommend to u
71. APSHOT ME F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Table 24 Parameters for the template xSHOOT Doc Issue Date Page VLT MAN ESO 14650 4942 P97 19 08 2015 126 of 161 ER slt_obs AutoNodOnSlit It allows to observe nodding along the slit The values of the nodding and jitter correspond to the width of the box float values are allowed XSHOOTER_slt_obs_AutoNodOnSlit Keyword Range Default Value Label in P2PP Free parameters INS OPTI3 NAME see Table 4 1 0x11 UVB slit INS OPTI4 NAME see Table 7 0 9x11 VIS slit INS OPTI5 NAME see Table 8 0 9x11 NIR slit DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 9999 1 Number of DITs SEQ NEXP UVB 0 100 1 UVB number of exposures per offset position SEQ NEXP VIS 0 100 1 VIS number of exposures per offset position SEQ NEXP NIR 0 100 1 NIR number of exposures per offset position SEQ SKYTHROW 0 10 5 Nod Throw in SEQ JITTER WIDTH 0 2 0 Jitter box width in SEQ NABCYCLES 0 100 1 Number AB or BA cycles SEQ OFFSET ZERO SE T Return to Origin Fixed Values INS MODE SLITSPEC
72. DEC It is also important to take into account the proper motions of the objects 7 1 3 Acquisition templates Slit acquisition templates We encourage the users to select the filter in which the target is best visible We also advice to set the shortest possible acquisition exposure time see Section 2 2 1 4 This would allow a minimum acquisition overhead Table 18 User defined and fixed keywords for XSHOOT ER slt acq XSHOOTER_slit_acq Keyword Range Default Value Label in P2PP Free parameters TEL TARG ALPHA 000000 000 Target RA TEL TARG DELTA 000000 000 Target DEC TEL TARG EQUINOX 2000 3000 2000 Equinox TEL TARG PMA 10 0 10 0 0 0 RA proper motion yr TEL TARG PMD 10 0 10 0 0 0 DEC proper motion yr TEL TARG EPOCH 1950 2000 2000 Epoch TEL TARG ADDVELALPHA 0 0 RA differential tracking velocity s TEL TARG ADDVELDELTA 0 0 DEC differential tracking velocity s TEL TARG OFFSETALPHA 36000 36000 0 0 RA blind offset TEL TARG OFFSETDELTA 36000 36000 0 0 DEC blind offset TEL ROT OFFANGLE 179 99 179 99 9999 Slit position angle on Sky 9999 9999 for parallactic angle INS FILT1 NAME u g r P z U A amp G filter B V R DET4 WIN1 UIT1 0 36000 TCCD exposure time TEL AG GUIDESTAR CATALOGUE CATALOGUE Telescope guide star SETUPFILE selection mode NONE TEL GS1 ALPHA 0 0 Guide
73. Data Prod Tech ECHELLE IFU OFFSET ECHELLE IFU STARE ECHELLE SLIT ECHELLE SLIT OFFSET ECHELLE SLIT STARE ECHELLE MULTI PINHOLE ECHELLE SLIT NODDING IMAGE IMAGE DPR TYPE yes OBJECT OB Data Prod Type JECT OFFSET BIAS DARK FLAT LINEARITY DETCHAR FLAT SKY LAMP FLAT LAMP ORDERDEF LAMP AFC STD FLUX STD TELLURIC STD ASTROMETRY STD TELLURIC ARC OBJECT INS FILT1 NAME no u_prime g prime rprime i_prime z prime U B V RI V G Filter SEQ PRESET yes FT 7 Preset flag TEL AG GUIDESTAR no CATALOGUE SETUPFILE Get Guide Star from NONE CATALOGUE TEL GS1 ALPHA no ra RA of guide star TEL GS1 DELTA no dec DEC of guide star TEL ROT OFFANGLE no 179 99 179 99 9999 0 9999 0 Position Angle on Sky TEL TARG ADDVELALPHA yes 0 0 Additional Velocity RA in arcsec s on the sk TEL TARG ADDVELDELTA yes 0 0 Additional Velocity DEC in arc sec s on the sky TEL TARG ALPHA no ra Q00000 000 RA TEL TARG DELTA no dec Q00000 000 DEC TEL TARG EPOCH no 1950 2000 2000 Epoch TEL TARG EQUINOX no QUERY TARG getEquinoxList Equinox TEL TARG OFFSETALPHA no 6000 36000 Offset RA TEL TARG OFFSETDELTA no 36000 36000 0 Offset DEC TEL TARG PMA yes 10 10 A Proper motion in RA TEL TARG PMD yes 10 10 0 Proper motion in DEC Parameter Hidden Value Label This template presets the telescope but does not request any active optics or guiding This template can be combined with the skyflats template XSHOOTER_img_cal_Flat tsf ESO Karl Schwarzschi
74. ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 85 of 161 Important warning because the detector is cooled by a Pelletier it takes time to evacuate the heating towards the cooling pipes that cool down the Pelletier itself As a consequence every time a loop is started or the integration time is modified the first exposures will have a higher background and noise than optimal It is therefore recommended to take a series of 2 to 3 images per position filter exposure time The example Antenna galaxy B filter 5s exposure time below illustrates this effect of the Pelletier cooling delay More details appear in the second exposure while the seeing did not vary First exposure of the series The bkg is at 1800 ADUs and the RMS at 12 ADUs Second exposure the bkg is now at 1711 ADUs and the RMS at 6 5 ADUs Ideally the dark should also be corrected from the images taken with this camera However the dark frames are not taken as part of the calibration plan therefore we strongly encourage the users to request such darks to be taken during daytime if needed ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Table 1bis A amp G CCD characteristics Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 86o0f 161 Pixel scale pixel Field of view Detector type E2V CCD57 1
75. HOOTER_slt_cal_Tellurics identical to the XSHOOTER slt obs Stare one tdStare The template is XSHOOTER _slit_cal_TelluricStdStare Keyword Range Default Value Label in P2PP Free parameters INS OPTI3 NAME see Table 4 1 0x11 UVB slit INS OPTI4 NAME see Table 7 0 9x11 VIS slit INS OPTI5 NAME see Table 8 0 9x11 NIR slit DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR_ see Table 5 100k 1pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXPO UVB 0 100 1 UVB number of exposures SEQ NEXPO VIS 0 100 1 VIS number of exposures SEQ NEXPO NIR 0 100 1 NIR number of exposures Fixed Values INS MODE IFUSPEC SLITSPEC SLITSPEC Instrument Mode SEQ AGSNAPSHOT I F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 138 of 161 Table 37 User defined and fixed parameters for SHOOT_slt cal TelluricStdNod The template is identical to the XSHOOTER slt obs AutoNodOnSlit one XSHOOTER _sit_cal_TelluricStdNod Keyword Range Default Value Label in P2P
76. M nchen Germany 1 4 List of Abbreviations amp Acronyms Doc Issue Date Page VLT MAN ESO 14650 4942 P97 19 08 2015 13 of 161 This document employs several abbreviations and acronyms to refer concisely to an item after it has been introduced The following list is aimed to help the reader in recalling the extended meaning of each short expression A amp G AG ADC AFC DCS DEC DFS DIT ESO ETC FDR FF GUI ICS IFU ISF IWS LCU N A OB PAE P2PP RA RMS RON SM TBC TCCD QE SNR TBD TCS TLI TSF VLT VM WCS ZP Acquisition and Guiding Atmospheric Dispersion Compensator Active Flexure Compensation Detector Control Software Declination Data Flow System Detector Integration Time European Southern Observatory Exposure Time Calculator Final Design Review Flat Field Graphical User Interface Instrument Control Software Integral Field Unit Instrument Summary File Instrument Workstation Local Control Unit Not Applicable Observing Block Preliminary Acceptance Europe Phase 2 Proposal Preparation Right Ascension Root Mean Square Readout Noise Service Mode To Be Clarified Technical CCD Quantum Efficiency Signal to Noise Ratio To Be Defined Telescope Control Software Threshold Limited Integration Template Signature File Very Large Telescope Visitor Mode World Coordinate System Zeropoint ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc Issue Date
77. P Free parameters INS OPTI3 NAME see Table 4 1 0x11 UVB slit INS OPTI4 NAME see Table 7 0 9x11 VIS slit INS OPTI5 NAME see Table 8 0 9x11 NIR slit DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 9999 1 Number of DITs SEQ NEXP UVB 0 100 1 UVB number of exposures per offset position SEQ NEXP VIS 0 100 1 VIS number of exposures per offset position SEQ NEXP NIR 0 100 1 NIR number of exposures per offset position SEQ SKYTHROW 0 10 5 Nod Throw in SEQ JITTER WIDTH 0 2 0 Jitter box width in SEQ NABCYCLES 0 100 1 Number AB or BA cycles SEQ OFFSET ZERO T F T Return to Origin Fixed Values INS MODE IFUSPEC SLITSPEC SLITSPEC Instrument Mode SEQ AGSNAPSHOT T F F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 139 of 161 Table 38 User defined and fixed parameters for SHOOT ifu cal TelluricStdStare The template is identical to xSHOOTER ifu obs Stare XSHOOTER_ifu_cal_TelluricStdStare Keyword Range Default Value Label in P2PP Free parameters DET1 WIN1 UIT1 0
78. PP Free parameters SEQ RRM REGISTER TE T Register OB in RRM system SEQ RRM VISITOR T F T Allow RRM activation in visitor mode TEL TARG ALPHA 000000 000 Target RA TEL TARG DELTA 000000 000 Target DEC TEL TARG EQUINOX 2000 3000 2000 Equinox TEL TARG EPOCH 1950 2000 2000 Epoch TEL TARG PMA 10 0 10 0 0 0 RA proper motion year TEL TARG PMD 10 0 10 0 0 0 DEC proper motion year TEL TARG ADDVELALPHA 0 0 Additional velocity RA in Is TEL TARG ADDVELDELTA 0 0 Additional velocity DEC in Is TEL TARG OFFSETALPHA 0 0 RA blind offset_ TEL TARG OFFSETDELTA 0 0 DEC blind offset TEL ROT OFFANGLE 179 99 179 99 9999 IFU position angle on Sky 9999 9999 for parallactic angle INS FILT1 NAME u g r i z U B A amp G filter V R DET4 WIN1 UIT1 0 36000 TCCD exposure time SEQ IFU WLGT 300 2000 470 Wavelength for target centring and tracking TEL AG GUIDESTAR CATALOGUE CATALOGUE Telescope guide star SETUPFILE selection mode NONE TEL GS1 ALPHA 0 0 Guide Star RA TEL GS1 DELTA 0 0 Guide Star DEC Fixed parameters DET1 WIN1 UIT1 2 AFC UVB exposure time DET2 WIN1 UIT1 0 5 AFC VIS exposure time DET3 DIT 1 AFC NIR DIT DET3 NDIT 1 Number of AFC NIR sub integrations NDIT SEQ AFC CORRECT Pal T AFC correct flag SEQ AFC MAXD 20 Maximum distance for AFC cross correlation SEQ AFC WSIZE 64 Window size for AFC cross correlation SEQ PRESET TE T Preset flag INS MODE SLITSPEC IFUSPEC Instrument mode IFUSPEC
79. R ifu cal SpecphotStdOffset ER ifu_obs FixedSkyOffset The XSHOOTER_ifu_cal_SpecphotStdOffset Keyword Range Default Value Label in P2PP Free parameters DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB read out mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS read out mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXP UVB 0 100 1 UVB number of exposures per offset position SEQ NEXP VIS 0 100 1 VIS number of exposures per offset position SEQ NEXP NIR 0 100 1 NIR number of exposures per offset position SEQ FIXOFF RA 100 100 0 RA fixed offset SEQ FIXOFF DEC 100 100 0 DEC fixed offset SEQ JITTER WIDTH 0 2 0 Jitter box width in SEQ NABCYCLES 0 100 1 Number OS or SO cycles SEQ OFFSET ZERO T F T Return to Origin Fixed Values INS MODE SLITSPEC IFUSPEC IFUSPEC Instrument Mode INS OPTI3 NAME see Table 4 1x12 6 UVB slit INS OPTI4 NAME see Table 7 1x12 6 VIS slit INS OPTI5 NAME see Table 8 1x12 6 NIR slit SEQ AGSNAPSHOT T F F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Telluric standards Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 137 of 161 Table 36 User and fixed keywords for XS
80. Reduction Sky darktime nm Yo factor e s pix e s pix e s pix 1048 0 0195 0 056 65 2 9 0 018 1238 0 027 0 10 73 3 7 0 022 1300 0 035 0 13 73 3 7 0 040 1682 0 040 0 15 73 3 8 0 050 The measurements see above table show that with the blocking filter the background is reduced in J and H bands by factors 3 to 4 They also show that at 1300nm for the slits with blocking filter the background would be sky limited not taking into account the RON For more complete information see next pages the figures and explanations ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 45 of 161 The figures below for the 0 9 and 0 6 slits with without filter show the different noises at different wavelength taking into account all the sources of background noises thermal background RON sky background dark current The black curve corresponds to the RON The back dashed curve corresponds to the dark current The dashed color curves correspond to the measurements at different wavelength for the slit without filter the normal color curves correspond to the measurements at different wavelength for the slit with filter A Background with 0 9 slits with without filters a For 0 9 slit with K band blocking filter Unfortunately the background is always RON limited for DIT shorter than 1000s whatever the wavelength is for this sl
81. SURE XSHOOTER _ifu_acq_RRM 360 Tel offset AG_EXPOSURE 3 AG_EXPOSURE if the AG_EXPOSURE time is setup at 1s XSHOOTER _sit ifu_acq 360 15 1 3 1 409s if the AG_EXPOSURE time is setup at 3mn or 180s XSHOOTER_sit ifu_acq 360 15 180 3 180 1025s If the AG exposure time is lower than 1s the wiping time for doing the snapshot takes about 1s therefore a minimum time of 1s is considered b Setup overheads In addition to these acquisition overheads overheads regarding the instrument setup must be added For the slit mode the setup overhead is 30s while for the IFU mode it lasts for 60s In the case of Integration time of 1s XSHOOTER_sit_acq setup 409 30 439s XSHOOTER_ifu_acq setup 409 60 469s Integration time of 180s XSHOOTER_slt_acq setup 1025 30 1055s XSHOOTER_ifu_acq setup 1025 60 1085s In addition to these times wiping time of the detector 6 1s has to be taken into account and the readout times c Delay before start of exposures In addition there is a delay of 5 s before the start of the VIS exposure and a delay of 10 s before the start of the NIR exposure d Readout overheads Because the UVB and VIS arms share the same FIERA controller if the exposure of CCD1 ends while the controller is reading CCD2 the readout of CCD1 will only take place once the readout of CCD2 is finished This must be compared to the execution of the NIR arm and the slowest of NIR vs UVB VIS arms gives the final execution time In
82. Star RA TEL GS1 DELTA 0 0 Guide Star DEC Fixed parameters DET1 WIN1 UIT1 2 AFC UVB exposure time DET2 WIN1 UIT1 0 5 AFC VIS exposure time DET3 DIT 1 AFC NIR DIT DET3 NDIT 1 number of AFC NIR DITs SEQ AFC CORRECT El T AFC correct flag SEQ AFC WSIZE 64 Window size for AFC Cross Correlation SEQ AFC MAXD 20 Maximum distance for AFC Cross Correlation SEQ PRESET ibs T Preset flag INS MODE SLITSPEC SLITSPEC Instrument mode IFUSPEC ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Table 19 User defined and fixed keywords for XSHOOT Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 121 of 161 ER slt acq rmm XSHOOTER_sit_acq_rrm Keyword Range Default Value Label in P2PP Free parameters SEQ RRM REGISTER TE T Register OB in RRM system SEQ RRM VISITOR T F T Allow RRM activation in visitor mode TEL TARG DELTA 000000 000 Target DEC TEL TARG EQUINOX 2000 3000 2000 Equinox TEL TARG PMA 10 0 10 0 0 0 RA proper motion year TEL TARG PMD 10 0 10 0 0 0 DEC proper motion year TEL TARG EPOCH 1950 2000 2000 Epoch TEL TARG ADDVELALPHA 0 0 RA differential tracking velocity s TEL TARG ADDVELDELTA 0 0 DEC differential tracking velocity s TEL TARG OFFSETALPHA 36000 36000 0 0 RA blind offset TEL TARG OFFSETDELTA 36000 36000 0 0 DEC blind offset
83. TER ifu obs StareSynchro should be used In this case the number of exposures is fixed to one per arm Exposure times can still be different in each arm but the exposures are synchronized to their mid time In case the exposure times in all three arms are identical exposures in the three arms will have the same start time within approximately one second In case of different exposure times the mid exposure time of the three will coincide within about one second ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 77of161 3 4 4 Nodding along the slit SLIT only This corresponds to the standard way of observing in the near IR primarily aimed at a double pass sky subtraction The template XSHOOTER slt obs AutoNodOnSlit automatically nods the telescope between two positions A and B along the slit The user defines a Nod Throw and optionally a small jitter box in the slit direction The Nod Throw is defined as the distance between the two nodding position i e the center of the two jitter boxes inside the slit see Figure 17 Ditto for the jittering box the jitter value corresponds to the size of the box One cycle is a pair of AB or BA observations Cycles are repeated in ABBA sequences For each arm the user chooses the number of exposures at each position and the exposure time both identical for all A and B positions Exposures are asynchronous Note
84. TG yes ACQUISITION Data Prod Cath DPR TECH yes IMAGE Data Prod Tech DPR TYPE yes OBJECT Data Prod Type INS FILTI NAME no u_prime g_prime r_prime i_prime z_prime UB VRI V G Filter SEQ PRESET yes FT T Preset flag TEL AG GUIDESTAR no CATALOGUE SETUPFILE Get Guide Star from NONE CATALOGUE TEL GS1L ALPHA no raf RA of guide star TEL GS1 DELTA no dec DEC of guide star TEL ROT OFFANGLE no 179 99 179 99 9999 0 9999 0 Position Angle on Sky TEL TARG ADDVELALPHA yes 0 0 Additional Velocity RA in arcsec s on the sky TEL TARG ADDV ELDELTA yes 0 0 Additional Velocity DEC in arc sec s on the sky TEL TARG ALPHA no ra 000000 000 RA TEL TARG DELTA no dec 000000 000 DEC TEL TARG EPOCH no 1950 2000 2000 Epoch TEL TARG EQUINOX no QUERY TARG _ getEquinoxList Equinox 2000 TEL TARG OFFSETALPHA no 36000 36000 0 Offset RA TEL TARG OFFSETDELTA no 36000 36000 0 Offset DEC TEL TARG PMA yes 10 10 0 Proper motion in RA TEL TARG PMD yes 10 10 0 Proper motion in DEC Parameter H dden Value Label ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 ES Q Issue P97 0 Date 19 08 2015 Page 156 of 161 Special imaging acquisition template for taking imaging skyflats SHOOTER jmg_acq_Plats DET4 WINLUITI no 0 36000 D Exposure time DPR CATG yes ACQUISITION SCIENCE CALIB Data Prod Cath TEST ACQUISITION DPR TECH yes ECHELLE ECHELLE FU
85. TYPE offsets e g O S S O SEQ OFFSET COORDS no SKY DETECTOR SKY Oai coord type RA DEC X Y SEQ OFFSET ZERO no TF T Go to zero offset position at the end SEQ RELOFFI no 1000 1000 7 List of RA X offsets SEQ RELOFF2 no 1000 1000 7 List of DEC Y offsets arameter H n Value La ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany DAYTIME IMAGING TEMPLATES Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 159 of 161 Calibration template for biases DET4 WIN1 UIT1 0 s and darks DET4 WIN1 UIT1 gt 0 s XSHOOTER_img_cal_Dark tsf To be specified Parameter Hidden Range Default Label DET4 WIN1 UIT1 no 0 36000 TCCD Exposure time DPR CATG yes CALIB Data Prod Cath DPR TECH yes IMAGE Data Prod Tech DPR TYPE yes BIAS Data Prod Type SEQ NEXPO no 0 100 7 Number of exposures Fixed values Parameter Hidden Value Label Calibration template for twilight flatfield s XSHOOTER_img_cal_Flat tsf To be specified Parameter Hidden Range Default Label DET4 WIN1 UIT1 no 0 36000 TCCD Exposure time DPR CATG yes CALIB Data Prod Cath DPR TECH yes IMAGE Data Prod Tech DPR TYPE yes FLAT SKY Data Prod Type INS FILT1 NAME yes u_prime g_prime r_prime i_prime z prime U B V R I PV B PV V V G Filter SEQ NEXPO no 0 100 7 Number of exposures arameter dden alue La Calibration template to m
86. U Beam separation Two high efficiency dichroics Atmospheric dispersion compensation In the UV Blue and Visual red arms Disabled on Aug 1st 2012 Integral field unit 1 8 x 4 reformatted into 0 6 x 12 Acquisition and quiding camera 1 5 x1 5 Johnson and SDSS filters ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 12 of 161 1 1 Scope The X shooter User Manual provides extensive information on the technical characteristics of the instrument its performances observing and calibration procedures and data reduction 1 2 X shooter in a nutshell X shooter is a single target spectrograph for the Cassegrain focus of one of the VLT UTs covering in a single exposure the spectral range from the UV to the K band The spectral format is fixed The instrument is designed to maximize the sensitivity in the spectral range through the splitting in three arms with optimized optics coatings dispersive elements and detectors It operates at intermediate resolutions R 4000 18000 depending on wavelength and slit width sufficient to address quantitatively a vast number of astrophysical applications while working in a background limited S N regime in the regions of the spectrum free from strong atmospheric emission and absorption lines A 3D CAD view of the instrument attached to the telescope is shown on Figure 1 Main instrument characteristics are summa
87. UVB readout mode DET2 WIN1 UIT1 0 36000 VIS Exposure Time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXPO UVB 0 100 1 UVB number of exposures SEQ NEXPO VIS 0 100 1 VIS number of exposures SEQ NEXPO NIR 0 100 1 NIR number of exposures Fixed Values INS MODE SLITSPEC SLITSPEC Instrument Mode IFUSPEC SEQ AGSNAPSHOT T F F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc Issue Date Page VLT MAN ESO 14650 4942 P97 19 08 2015 125 of 161 Table 23 Parameters for synchronized stare UVB VIS and NIR observations with the template XSHOOTER slt obs StareSynchro XSHOOTER_slt_obs_StareSynchro Keyword Range Default Value Label in P2PP Free parameters INS OPTI3 NAME see Table 4 1 0x11 UVB slit INS OPTI4 NAME see Table 7 0 9x11 VIS slit INS OPTI5 NAME see Table 8 0 9x11 NIR slit DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 66 36000 NIR Detector Integration Time s DET3 NDIT 1 9999 1 number of DITs Fixed Values INS MODE SLITSPEC SLITSPEC Instrument Mode IFUSPEC SEQ AGSN
88. Values INS MODE SLITSPEC IFUSPEC Instrument Mode IFUSPEC INS OPTI3 NAME see Table 4 1x12 6 UVB slit INS OPTI4 NAME see Table 7 1x12 6 VIS slit INS OPTI5 NAME see Table 8 1x12 6 NIR slit SEQ AGSNAPSHOT TE F Take an acquisition image before science exposures Table 28 User defined and fixed parameters for the template XSHOOTER ifu obs StareSynchro to perform synchronized observations in stare mode XSHOOTER slit_ifu_StareSynchro Keyword Range Default Value Label in P2PP Free parameters DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs Fixed Values INS MODE SLITSPEC IFUSPEC Instrument Mode IFUSPEC INS OPTI3 NAME see Table 4 1x12 6 UVB Slit slide INS OPTI4 NAME see Table 7 1x12 6 VIS Slit slide INS OPTI5 NAME see Table 8 1x12 6 NIR Slit slide SEQ AGSNAPSHOT IF F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Table 29 User defined and Doc Issue VLT MAN ESO 14650 4942 P97 Date 19 08 2015 Page 130 of 161 fixed parameters for the template XSHOOTER ifu obs FixedSkyOffset It allows to alterna
89. _dist once per year or user provided The count levels of the twilight flats should be between 10000 and 55000 ADUs In P93 they will be taken pointing to empty sky positions while until P92 they are taken at the zenith thus star traces may be possible d Quality control Some health check plots of the AGCCD are available at http www eso org observing dfo quality XSHOOTER reports HEALTH trend report BIAS A GC_HC html the bias level the readout noise the noise structure the dark current are monitored The linearity and gain are also monitored but there is no plot yet available ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany ES Q Issue P97 QO Date 19 08 2015 Page 93 of 161 Distortion map fringes and astrometric accurac Doc VLT MAN ESO 14650 4942 Figure 5bis shows the distortion maps of the TCCD with respect to the 2MASS astrometry Fig 6bis 400 Y pix 200 400 Y pix 200 N Zz mh nih ft fy An RL ee herd DEN 1 1 NRA ANN N a reat ny ryt is vant 1 f SAAN ZAARA A iyt 4 ri a a L N a 4 N 4 YM u 200 200 X pix R band X pix I band Figure 5bis UBVRI distortion maps magnified x20 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany ws x 5 ue
90. ab TY i ae Z Mtl ae Wn ete eg NON tfh i N AN fr SW LL FERN J r 200 200 o 400 X pix U band X pix B band X pix V band Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 94 of 161 0 1 0 01 0 1 0 0 1 RA arcsec Dec arcsec Fig 6bis Distributions in RA and DEC of the difference between 2MASS and the AGCCD astrometry The difference between 2MASS and the A amp G CCD astrometry is 0 1 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc Issue Date Page The Fringing maps were obtained with skyflats The most affected filters are the r i z VLT MAN ESO 14650 4942 P97 19 08 2015 95 of 161 The amplitude peak to peak ranges from 2 in the r to 4 in the z filter Ta ar a tS etsy i op ee ser a pk ca BR ee RE HR TES w i ox Projection Projection 1 04 1 04 1 02 1 02 4 g lt lt 8 2 i d 1 Hl i ATL NT on 0 98 0 96 165 978 165 974 165 971 165 967 10 070 10 073 10 076 10 080 wes 121 815 121 810 121 805 121 801 26 980 26 982 26 984 26 987 wes Fig 7bis Fringing maps in r and z The cuts in the bottom show the amplitude peak to peak of the fringes ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 96 0f 161 eCalibration frames overview and examples Figure 8bis Three color BVI image of a g
91. alaxy with a supernova left and of a small field of 47Tuc right Observations were performed in stare mode More examples are shown in the Messenger article of the XSHOOTER imaging mode ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 970of161 Figure 9bis Example of calibration images A amp G CCD bias A amp G CCD twilight U band flatfield A amp G CCD twilight B band flatfield A amp G CCD twilight V band flatfield A amp G CCD twilight R band flatfield A amp G CCD twilight band flatfield ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 98 of 161 eData reduction No pipeline support will be provided for the imaging data as there are lots of tools to reduce imaging data extract the objects and do the photometry Pipeline support will be provided for the detector linearity determination only Below are some basic guidelines of imaging data reduction with IRAF and the swarp software 0 Preliminary steps elnspect the images reject the flat fields with too many stars or star traces eCreate files listing the frames per type eMake sure to use darks and flat fields with the same integration times 1 Create the masterbias eln IRAF use the imcombine task to median combine the bias images x SG emartsysn nboi 045
92. alibration template for observation of standard field for distortion map same functionality as the science imaging generic offset template XSHOOTER_img_obs_cal_dist tsf To be specified en Range Da a _____ DET4 WINI 0 36000 1 TCCD Exposure time DPR C peg yes CALIB Data Prod Cath DPR TECH yes IMAGE Data Prod Tech DPR TYPE yes STD ASTROMETRY Data Prod Type INS FILTI NAME no u_prime g_prime r_prime i_prime z_prime U B V R I V G Filter SEQ NEXPO no 0 100 7 Number of exposures SEQ NOFFSET no 1 100 2 Number of offsets SEQ OBS TYPE no OS List of TYPE offsets e g O S SO SEQ OFFSET COORDS no SKY DETECTOR SKY Oei coord type RA DEC X Y SEQ OFFSET ZERO no TF T Go to zero offset position at the end SEQ RELOFFI no 1000 1000 7 List of RA X offsets SEQ RELOFF2 no 1000 1000 7 List of DEC Y offsets arameter Hi n Value La Calibration template for observation of standard fields for zeropoint determination same functionality as the science imaging generic offset template XSHOOTER_mg_obs_cal_phot tsf To be specified Parameter Hilden T Range Dep a ooo 0 36000 1 TCCD Exposure time ai i n yes CALIB Data Prod Cath DPR TECH yes IMAGE Data Prod Tech DPR TYPE yes STD FLUX Data Prod Type INS FILT1 NAME no u_prime g prime r_prime i prime z_prime U B V R I V G Filter SEQ NEXPO no 0 100 7 Number of exposures SEQ NOFFSET no 1 100 2 Number of offsets SEQ OBS TYPE no OS List of
93. ases monthly detector monitoring Set of detector PN LINEARITY_VIS_400k_2x2 FF biases monthly detector monitoring Set of LINEARITY_NIR detector monthly detector monitoring FF Imaging mode darks Skyflats linearity monthly All of these calibrations are taken for the monitoring of the instrument health but also for calibrating the science and calibration telluric and flux standard stars observations One should use at the time of the data reduction both daily and long term calibrations in the different corresponding pipeline recipes ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 107 of 161 6 2 Wavelength and spatial scale calibration As described in section 2 3 1 the spectral format of X shooter is relatively complex with highly curved orders variable line tilt dispersion and spatial scale along each order Using just long slit arc spectra is not sufficient because it is essential to also calibrate the change of spatial scale just measuring the slit height is not accurate enough Wavelength and spatial scale are well calibrated simultaneously with a dedicated mask of 9 equidistant pinholes present in each slit unit see Table 4 Table 7 and Table 8 in combination with the ThAr lamp Exposure time for each arm is given in Table 17 An example of such a frame is given in Figure 18 The templates used for this calibration
94. asurements one must not try to observe stars brighter than magnitude 3 because it will lead to saturate the detectors It is the case of an AOV or O5 or FO stars observed under a seeing of 0 8 at an airmass of 1 2 with the slits 0 5 in the UVB 0 4 in the VIS 0 4 in the NIR and integration times of 0 1s in the UVB and VIS and the minimum DIT 0 66s in the NIR In case of saturation indicated by the ETC for the object try to reduce the exposure time if possible and to choose a narrower slit Usually the OBs have to be observed within the specification i e with better conditions than requested but in such case for bright objects the detector can saturate leading to time losses useless data remnants in different arms and possibility to classify the OB as not feasible no repeated observation Thus we strongly encourage the users to check their objects with the ETC and to avoid observing extremely bright objects Ditto we encourage the users to check that the counts never enter the extrapolated regime of readout in the NIR A diaphragm mode has been tested It allows to observe ultra bright targets down to magnitude 4 It opens new windows on well known objects but still without spectra especially in the infrared due to their brightness A report as well as the reduced data obtained during the tests is available at http www eso orq sci facilities paranal instruments xshooter news html It is not yet decided whether
95. avelength solution Table 58 User and fixed keywords for XSHOOT ER slt cal UVBVisArcsSinglePinhole XSHOOTER_slit_cal_UVBVisArcsSinglePinhole Free Parameters Keyword Range Default Value Label in P2PP DET1 WIN1 UIT1 0 36000 40 UVB Exposure Time DET1 READ CLKDESCR see Table 5 400k 1pt Ig UVB readout mode DET2 WIN1 UIT1 0 36000 15 VIS Exposure Time DET2 READ CLKDESCR see Table 5 400k 1pt lg VIS readout mode SEQ NEXPO UVB 0 100 1 No of UVB exposures SEQ NEXPO VIS 0 100 1 No of VIS exposures Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode INS OPTI3 NAME see Table 4 Pin_0 5 UVB slit INS OPTI4 NAME see Table 7 Pin_0 5 VIS slit Table 59 User and fixed keywords for XSHOOT ER slt cal NIRArcsSinglePinhole XSHOOTER_slit_cal_NIRArcsSinglePinhole Free Parameters Keyword Range Default Value Label in P2PP DET3 DIT 0 36000 10 NIR Exposure Time DET3 NDIT 1 20 5 Number of DITs SEQ NEXPO 0 100 1 NIR of exposure Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode INS OPTI5 NAME see Table 8 Pin_0 5 NIR slit Order definition 1 guess of order localization Table 60 User and fixed keywords for XSHOOT ER slt cal UBVLampFlaSinglePinhole XSHOOTER_slit_cal_UVBLampFlatSinglePinhole Free Parameters Keyword Rang
96. cal mounted on a tip tilt stage and used for flexure compensation see description on p 24 light enters the cryostat via the Infrasil vacuum window To avoid ghosts this window is tilted 3 degrees about the Y axis After the window light passes the cold stop and is directed towards the entrance slit via two folding mirrors M3 flat and M4 spherical 2 2 6 2 Slit wheels A circular laser cut Invar slit mask is pressed in between two stainless steel disks with 12 openings forming the wheel The wheel is positioned by indents on the circumference of the wheel with a roll clicking into the indents All the science observation slits are 11 high and different widths are offered from 0 4 to 5 see Table 8 Table 8 NIR spectrograph slits and calibration masks Size Purpose 0 4 x11 slit SCI CAL 0 6 x11 slit SCI CAL 0 9 x11 slit SCI CAL 1 2 x11 slit SCI CAL 5 0 x11 slit CAL 0 6 x11 JH slit SCI CAL 0 9 x11 JH slit SCI CAL Row of 9 pinholes of 0 5 spaced at 1 4 SAL 0 5 pinhole CAL Blind SCI CAL In July 2011 during the intervention on XSHOOTER the NIR slit wheel was modified the 1 5 slit was removed not offered since P88 and 2 new slits of 0 6 and 0 9 with a stray light K band blocking filter added Scattered light from the strong thermal radiation in the reddest order of the NIR arm affects very significantly the background level in the
97. can never follow a SLIT acquisition sequence and vice versa At the end of the acquisition sequence an acquisition image of the field is saved after blind offsets have been applied if any Till P92 every time an offset was performed the acquisition image was saved disabled in P93 This was useful for quickly varying objects such as GRBs but this is now obsolete with the offered imaging mode ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 66 of 161 FITS header keywords HIERARCH ESO SEQ AG XCEN and YCEN record the location of the centre of the SLIT or IFU in the image 3 2 2 Blind offset precisions For targets fainter than 22mag see Table 3 we recommend to perform a blind offset from a reference star For a blind offset acquisition the coordinates of the reference target reasonably bright star needs to be given in the target field in the OB and not the coordinates of the target itself This reference target is then centered on the slit IFU during the acquisition see 3 2 1 The offset to the science target is specified in the acquisition template as Offset RA and Offset DEC These offsets are given in arcsec and denote offsets on sky This means that e g an offset of offset RA 10 5 and offset DEC 5 0 will move the slit to a target that is 10 5arcsec East and 5 0arcsec South of the reference target Both the reference
98. ceeeeeeeeeeeeeeeeeeeeees Acquisition templates ccccccccceeeeeeeeeeeeeeeeeaeeeaeeeeeeeeeesaaaeaceeeeeeeeeeaaaeaaeees t acquisition templates 444sannssennnnnnnennnnnnnnnnnnnnnennnnnnnnnnnnnnnnnsnnnnrnnn IFU acquisition templates 00n000snnnennnennnnnnnnnnnnnnnnennnnnnnnnnnnnnnennnnnnrnrn 7 1 4 7 1 5 Sli Flexure compensation templates that can be used in OBS Science templates nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnsnsnnnnn na 10191151 A02 111010 EE an a a ae ua EEEE E E IFU observations rieka a a EA a a E SEAE AA NEA EER 7 1 6 Night time Calibration Templates 444244444440nnnnnnnnnnnnnnnnnnnnnnnnnnnn Spectro photometric Standard Stars ccccccccccccccccessesseccceeseeeeeaeeeseceeeeeeeeeaaneeeess Telluric standards 4422444444444444annnnnnnnnnnnennnnnnnennnnnnnnennnnnnennnnnnnnsnnnnrnnn Attached night calibrations must be taken after a science template Arcs multi pinhole 2d wave maps wavelength calibration 444 7 1 7 Sli Daytime Calibration templates uur4444444444BBnnnnnnnnnnnnnnnnnnnnnnnnnnnn t and IFU arc lamp calibrations resolution tilt nnneeeeeennnneeneeeeeeeennrnn reesen Flatfield pixel response orders localization 2222244444420000000Rnnnnn nennen F
99. ch corresponds to an accuracy of 7 5 km s at 800 nm 0 004 nm in the NIR arm which corresponds to an accuracy of 0 6 km s at 2 um ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc Issue Date Page 2 4 10 NIR 11 order vignetting K band VLT MAN ESO 14650 4942 P97 19 08 2015 61 of 161 The flux in this 11 order decreases towards the top of the order by a factor of 10 and is due to a bad design of the mask located in front of the NIR array The same effect is present in the blue part of the 10 order Figure 15 NIR11 order vignetting corresponding to a flux decrease arrow Figure from L Christensen technical note Trying to correct this vignetting would imply a major operation on the NIR arm with possible risks to degrade much more the NIR performances than they currently are ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 62 of 161 2 4 11 VIS CCD pick up noise The pick up noise in the VIS detector is present in every readout modes with a deviation from the background level of lower than 0 5 This pick up noise is comparable to the pick up noise measured on the UVES CCD for example In case you want to observe faint targets with long exposure times it is not recommended to use the fast readout mode due to its readout noise In addition the fast readout mode of the VIS CCD shows a
100. ckground BEBERRERRPEFPEUFREEELFEHERELECHELEEEFCHFEELLLUREREELTUUEREEUPERFEEFLECHERELDERER 58 2 4 6 NIR frames with the K band blocking filter features eene 58 2 4 7 NIR detector interquadrant cross talk and electrical ghosts 60 2 4 8 Instrument stabilty zes anna RR 60 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 9 of 161 2 4 8 1 Backbone flOXULES cccccccccccccccceeeeeeeeeeeceeeeeeeeeeeeeeeeeeeseeeeeeeeeseseeeeeseseeeensenes 60 2 4 8 2 Spectrograph flexures cccccccccccccccccccccceeceeeeeeceeeceeeeeeeseeeeeeeeeeeeeeeeeeeseeeneeess 60 2 4 9 Radial velocity ACCUTaCy PRENRPRERRERRERFEHEHEENEERERELKEREERECHEFEFRELHEREERELHLERERELKERFERELHERERRERR 60 2 4 10 NIR 11 order vignetting K band c ccccccccccsssescssesesesescceeesceseesessstseeneatenes 61 2 4 11 VIS CCD pick up NOiSC ccccccccccccccecccccceccecccececececceeeeeececeeeceeeeeeeceeeseeeseeess 62 2 4 12 NIR IFU parasitic reflections ccccccccccccccccccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeess 62 2 4 13 UVB VIS ADCS problem cccccccccccccccccceeceeeeeeeeeeeeeseneeeseceseceseeeseeeeesesenenenass 63 2 4 14 Drift of acquisition reference positions 404444404000n0nnnnnnnnnnnnnnnnnnnenn 63 2 4 15 Historical wavelength shift between arms ssssssssssnnnnnnnennnnnnnnnnnnnnn 63 2
101. cription Target Constraint Set Time Intervals demonstration rTarget Name acquisition_star_blind_offset Right Ascension 10 00 00 000 Declination 12 12 12 120 Equinox J2000 Epoch 2000 0 Proper Motion RA 0 003000 Proper Motion Dec 0 005000 Diff RA 0 000000 Diff Dec 0 000000 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 75 of 161 3 4 Spectroscopic observations 3 4 1 Overview and important remarks 3 4 1 1 Observing modes X shooter science templates support different observing strategies staring commonly used for UV and visible observations nodding along the slit classical near IR observations for SLIT only offsetting to a fixed sky position for extended objects or lets the user free to choose any sequence of offsets e g for mapping Note that due to the small field of view of the IFU we recommend to offset to a pure sky position in case good sky subtraction is needed 3 4 1 2 Effect of atmospheric dispersion See section 2 2 2 for the update of the situation unfortunately the ADCs have been disabled due to their unreliability at night Therefore the observations are conducted with the ADCs fixed at the non deviation position for both the IFU and SLIT modes Obsolete In SLIT mode effects of atmospheric dispersion are a
102. ctroscopy and imaging The spectral format is fixed for both spectroscopic observing modes The three arms UVB VIS and NIR operate in parallel In SLIT mode the user can select for each arm independently a slit width among those listed in Table 12 In IFU mode the only important parameter the user has to choose is the wavelength that is placed and kept fixed at the centre of the IFU during observations See section 2 2 2 for indications about the effects of this wavelength choice on the spectrum flux depending on the orders In both spectroscopic observing modes one of the detector readout modes given in section 0 and 2 2 5 can be selected for the UVB and the VIS arm independently The readout mode is fixed for the NIR arm In IMAGING mode only the acquisition and guiding camera is used with the filters chosen by the users in the list of available filters This mode has to be combined to SLIT or IFU observations for science OBs in SM or can be used standalone in calibration OBs or in VM The calibration plan for this mode is quite limited because XSHOOTER remains first a set of spectrographs All X shooter science observing blocks OB are composed of an acquisition template see 3 2 followed by one or several science templates selected depending on the observing strategy chosen by the user ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 6
103. d Str 2 85748 Garching bei M nchen Germany 2 2 3 Detector QE curves Doc Issue Date Page UVB VIS Detectors 14 0 9 0 8 0 7 VLT MAN ESO 14650 4942 P97 19 08 2015 35 of 161 0 6 0 5 0 4 0 3 0 2 0 1 Efficiency Pisces Aus II Catherine 300 500 700 Wavelength 2 2 4 The UVB spectrograph 2 2 4 1 Slit carriage The first opto mechanical element of the spectrograph is the slit carriage Besides the slit selection mechanism this unit consists of a field lens placed just in front of the slit to re image the telescope pupil onto the spectrograph grating and the spectrograph shutter just after the slit The slit mask is a laser cut Invar plate manufactured with the LPKF Laser Cutter used for FORS and VIMOS It is mounted on a motorized slide in order to select one of the 9 positions available All science observation slits are 11 high and different widths from 0 5 to 5 the latter for spectro photometric calibration are offered In addition a single pinhole for spectral format check and order tracing and a 9 pinhole mask for wavelength calibration and spatial scale mapping are available see Table 4 900 1100 Table 4 UVB spectrograph slits and calibration masks Size Purpose 0 5 x11 slit SCI CAL 0 8 x 11 slit SCI CAL 1 0 x11 slit SCI CAL 1 3 x11 slit SCI CAL 1 6 x11 slit SCI CAL 5 0 x11 slit CAL Row of 9 pinholes of 0 5
104. d VIS 1x2 slow fast 45s 11s 2x2 slow fast 22s 5s NIR 1 46 Each telescope offset 15s Acquisition and guiding camera readout Less than 1s The overheads will be modified if some imaging is introduced in the OB after commissioning all the values will be published However from the preliminary tests the readout of the AG camera is fast less than 1s the change of filter takes less than 20s and the instrument setup depends from which mode the instrument goes to the imaging mode In case of IFU it takes about 45s In slit mode it takes lass than 10s a Acquisition overheads the acquisition time depends on the integration time set in the AG camera Direct acquisition loop Preset time Tel offset AG_EXPOSURE 3 AG_EXPOSURE saved Blind offset acquisition loop Preset time Tel offsett AG_EXPOSURE 3 telescope blind offset to target AG_EXPOSURE for check AG EXPOSURE saved Tel offset The telescope offset could be up to 15 sec The telescope blind offset to the target could be up to 30 sec Acquisition template acquisition time s aoe DEE RSS aaa tees Cee eae eee XSHOOTER_sit_acq 360 Tel offset AG_EXPOSURE 3 AG EXPOSURE XSHOOTER_ifu_acq 360 Tel offset AG_EXPOSURE 3 AG_ EXPOSURE ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 101 of 161 XSHOOTER_slt_acq_ RRM 360 Tel offset AG_EXPOSURE 3 AG_EXPO
105. d fixed parameters for the template as well the mapping template XSHOOTER_ifu_obs_GenericOffset Keyword Range Default Value Label in P2PP Free parameters DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXP UVB 0 100 1 UVB number of exposures per offset position SEQ NEXP VIS 0 100 1 VIS number of exposures per offset position SEQ NEXP NIR 0 100 1 NIR number of exposures per offset position SEQ OFFSET COORDS SKY SLIT SKY Offset coordinate type RA DEC or X Y SEQ RELOFF1 1000 1000 0 List of RA X offsets SEQ RELOFF2 1000 1000 0 List of DEC Y offsets SEQ OBS TYPE O S OS List of observation type object or sky SEQ NOFFSET 0 100 2 Number of offsets SEQ OFFSET ZERO T F T Return to Origin Fixed Values INS MODE SLITSPEC IFUSPEC Instrument Mode IFUSPEC INS OPTI3 NAME see Table 4 1x12 6 UVB Slit slide INS OPTI4 NAME see Table 7 1x12 6 VIS Slit slide INS OPTI5 NAME see Table 8 1x12 6 NIR Slit slide SEQ AGSNAPSHOT TF F Take an acquisition image before science exposures The MAPPING template has the same structure than the GENERIC OFFSET template but allows the freedom to have different number of
106. dgements warning about the snapshots during the acquisitions offsets that will not be saved anymore only last snapshots end of acquisition kept warning about the exposure times of all calibration frames that will be revised warning about the wavelength calibration at night that should be performed with 2dmap template instead of ARC Change of format doc to odt allowed 2dmap wave calibrations at night Move of XSHOOTER from UT2 to UT3 minor changes in various sections Back to format doc Introduction of the XSHOOTER imaging mode new sect 4 comments in various sections Minor changes every where ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany P95 P96 P97 26 02 2014 30 06 2014 All 20 11 2014 26 02 2015 23 06 2015 24 06 2015 19 08 2015 New sect 2 4 15 Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 7 of 161 Minor changes references to the imaging mode user manual added New table about the limiting magnitude for a S N 10 in sec 2 2 1 4 Some details provided for the dichroic dip oscillation corrected cross references CMA Merging imaging mode manual with main manual as per ESO standard Correction of some language issues obsolete sections removed or reorganized Radial velocity accuracy added telluric lines correction tool reference added updates of references and features Updates Sects 1 8 2 2 2 new sections
107. dout 1x1 binning exclusively used for flexure measurement and engineering purposes is also implemented Measured properties and performances of this system are summarized in Table 6 The associated shutter located just after the slit is a 25mm bi stable 2 coil zero dissipation shutter from Uniblitz type BDS 25 Full transit time is 13ms Since the slit is 2 8mm high 11 at f 6 5 the illumination of the detector is homogenous within lt lt 10ms ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc Issue P97 Date 19 08 2015 Page 38 of 161 VLT MAN ESO 14650 4942 readout time s Dark current level Fringing amplitude Non linearity Readout direction Prescan and overscan areas Flatness 1x2 slow fast 34 8 2x2 slow fast 17 4 lt 0 2e pix h Slow 0 4 Fast 1 0 Main disp dir 1x1 and 1x2 X 1 48 and 2097 2144 2x2 X 1 24 and 1049 1072 lt 8um peak to valley 1x2 slow fast 45 11 2x2 slow fast 22 5 lt 1 1e pix h 5 peak to valley Slow 0 8 Fast 0 8 Main disp dir 1x1 and 1x2 pix 39 48 and 2097 2144 2x2 19 24 and 1049 1072 UVB VIS NIR Detector type E2V CCD44 82 MIT LL CCID 20 substrate removed Hawaii 2RG Operating 153 K 135 K 81K temperature QE 80 at 320 nm 78 at 550 nm 85 88 at 400 nm 91 at 700 nm 83 at 500 nm 74 at 900 nm 81 at 540 nm 23 at 1000 nm Number of 2048x3000 2048x4096 2048x2048 pix
108. dout speed and a voltage parameter have been set to minimize their effects without increasing the readout noise but they can still appear from time to time More information is provided by the document http www eso org gfinger marseille 08 AS08 AS12 9 H2RG mosaic gfi final pdf Both features give artificial signals with a count level close to the sky background level This is mostly noticeable in the case of observations with the K band blocking filter 2 4 8 Instrument stability 2 4 8 1 Backbone flexures The active flexure compensation AFC allows to maintain the three slits aligned with respect to the reference A amp G pinhole to within 0 02 in both at any rotation angle for ZD lt 60 It is advised to run again the AFC procedure every hour it takes 70 80s to correct for both the effect of a varying gravity vector and drifts of the piezo mirror position related to the control electronics of these devices In all cases it is better not to skip the AFC when a new OB is started 2 4 8 2 Spectrograph flexures From 0 to 60 zenithal distance for any rotator angle the spectra format in all three arms stays within 1 2 pixels from the zenith position 2 4 9 Radial velocity accuracy Using the pipeline and the calibration frames especially the WAVE 2d map the systematic accuracy of the wavelength calibration is 0 03 nm in the UVB arm which corresponds to an accuracy of 20 km s at 450 nm 0 02 nm in the VIS arm whi
109. e Default Value Label in P2PP DET1 WIN1 UIT1 HIGHF 0 36000 30 UVB exposure time High Flat DET1 WIN1 UIT1 LOWF 0 36000 20 UVB exposure time Low Flat DET1 READ CLKDESCR see Table 5 400k 1pt lg UVB readout mode SEQ NEXPO HIGHF 0 30 1 No of exposures High Flat SEQ NEXPO LOWF 0 30 1 No of exposures Low Flat Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode INS OPTI3 NAME see Table 8 Pin_0 5 UVB Slit slide ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Table 61 User and fixed keywords for XSHOOT Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 150 of 161 ER slt cal VISLampFlatSinglePinhole XSHOOTER_sit_cal_VISLampFlatSinglePinhole Free Paramters Keyword Range Default Value Label in P2PP DET2 WIN1 UIT1 0 36000 60 VIS exposure time DET2 READ CLKDESCR see Table 5 400k 1pt lg VIS readout mode SEQ NEXPO 0 100 1 No of exposures Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode INS OPTI4 NAME see Table 7 Pin_0 5 VIS slit Table 62 User and fixed keywords for XSHOOT ER slt cal NIRLampFlatSinglePinhole XSHOOTER_sit_cal_NIRLampFlatSinglePinhole Free Parameters Keyword Range Default Value Label in P2PP DET3 DIT 0 36000 1 NIR exposure time DET3 NDIT 1 20 1 Number of DITs SEQ NEXPO 0 100 1 NIR No of
110. e exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc Issue VLT MAN ESO 14650 4942 P97 Date 19 08 2015 Page 134 of 161 Table 33 User defined and fixed parameters for xSHOOTER slt cal SpecphotNodding The template is identical to the XSHOOTER slt obs AutoNodOnSlit one XSHOOTER_slt_cal_SpecphotNodding Keyword Range Default Value Label in P2PP Free parameters INS OPTI3 NAME see Table 4 5 0 x11 UVB slit INS OPTI4 NAME see Table 7 5 0 x11 VIS slit INS OPTI5 NAME see Table 8 5 0 x11 NIR slit DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXP UVB 0 100 1 UVB number of exposures per offset position SEQ NEXP VIS 0 100 1 VIS number of exposures per offset position SEQ NEXP NIR 0 100 1 NIR number of exposures per offset position SEQ SKYTHROW 0 10 5 Nod Throw in SEQ JITTER WIDTH 0 2 0 Jitter box width in SEQ NABCYCLES 0 100 1 Number AB or BA cycles SEQ OFFSET ZERO T F T Return to Origin Fixed Values INS MODE SLITSPEC SLITSPEC Instrument Mode IFUSPEC SEQ AGSNAPSHOT T F F Take an acquisition image before science exposures
111. e science Declination 12 12 12 120 target in case of direct Equinox 2000 acquisition Epoch 2000 0 q class Teri coordinates RA DEC Proper Motion RA g 903000 equinox epoch proper motions in RA and DEC in arcsec year differential velocities in RA and DEC in s moving targets if any ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 70of 161 The following snapshots are valid for both direct and blind offset OBs l w rConstraint Set Obs Description Target Constraint Set ime Intervals demonstration x Name Sky Transparency Seeing arcsec Airmass Lunar Illumination Moon Angular Distance Twilight min aseline Strehl PWV mm standard_condition Clear z 0 8 Specify the constraints 1 5 Transparency seeing 1 0 etc 30 Atmospheric Turbulence Model ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 71 of 161 A g demonstration Jo w ay a fE Obs Description Target Constraint Set Time Intervals Date 10 Feb 11 Feb 12 Feb 13 Feb 14 Feb 15 Feb 16 Feb 17 Feb 18 Feb 19 Feb 20 Feb 21 Feb 22 Feb 23 Feb 24 Feb 25 Feb 26 Feb 27 Feb 28 Feb 1 Mar Time Intervals
112. e se euere e aee e a EE 37 2 2 5 The ViSspectograp ii a a EE EE EENE Ea EEA EEEE E 39 2291 Slitcariage nee ea 39 2 2 5 2 Optical layout BIBERBORREREIERELEEE EEOERESFELBEREEFPRCUFEERFERENDERFEOHFESCEIERDEFTEGEREEEFEERIERE PFENEERCFEERE 39 2 2 5 3 Detector usssssssssennnnsnnnnnennnnnnnnnnnnnnnnnnnnnnnnennnnnnnnnnnnnnnnssnnnrernnnnnne sn 39 2 2 6 The NIR spectrograph 444444s0nn0ennnnnnnnnennnnnnnnnnnnnnnennnnnnennnnnnnn nn 40 2 2 6 1 Pre slit optics and entrance window 22uuusssssnsssnssnnnnneennnnnnnnnnnnnnne nn 40 2252 SL WWCGIS een ken 40 2 2 6 3 NIR BackgroundS anaseeeneeen 44 2 2 6 4 Optical layout GOSPERDERERENEERERHERELHEERFHREHERFEBEENEEBRREENPEHEHECHEEHERREHEEFEBELHEEBEBEPEERFBECHELBEREEEE 47 2 2 0 9 DEIECIOr eascann aE A EEEE 48 2 3 Spectral format resolution and overall performances ccccceeeeeeeeeeeeeeeeeeeeeeees 51 2 3 1 Sp ctral fommna ne ee 51 2 3 2 Spectral resolution and sampling nennen 52 2 3 3 Overall sensitivity nase 53 2 4 Instrument features and known problems to be aware of ccccccccccseeeeeeeeeeees 55 2 4 1 UVB and VIS detectors sequential readout nnnnnnnnnrrrrrrrrrrrrrrrrrrrrrrrrnnna 55 2 4 2 Effects of atmospheric diSPersiOn ccccccccccccccccecccccceceeeeeeeeeeeeeeeeeseeeeeness 55 2 4 3 Remanence ai nn AE a E EEEE e Aea Hovde A II 55 2 4 4 COS e E E E E E E E E 57 2 4 5 Inter order ba
113. easure the detector gain and linearity XSHOOTER img_cal_DetLin tsf To be specified Parameter Hidden Range Default Label DET4 WINL UITI no 0 36000 7 TCCD Exposure time DPR CATG yes CALIB Data Prod Cath DPR TECH yes IMAGE Data Prod Tech DPR TYPE yes FLAT LINEARITY DETCHAR Data Prod Type INS FILT1 NAME no u_prime g_prime r_prime i_prime z prime U B V R I PV B PV V V G Filter SEQ EXPO STEP no 0 3600 7 Exposure time step SEQ NEXPO no 1 100 7 Number of exposures SEQ NLOOP no 1 100 2 Number of loops pairs Parameter Hidden Value Label ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany 7 2 Slit masks 7 2 1 UVB Table 71 full description of the UVB slit mask Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 160 of 161 Position Size Physcal size um Purpose 1 0 5 pinhole 126 hole CAL 2 5 x11 slit 1256 x 2763 CAL 3 1 6 x11 slit 402 x 2763 SCI CAL 4 1 3 x11 slit 327 x 2763 SCI CAL 5 0 8 x11 slit 201 x 2763 SCI CAL 6 1 x12 6 slit 251 x 3165 With IFU only 7 Raw of 9 pinholes of 0 5 126 holes spaced by CAL spaced at 1 4 352 8 0 5 x11 slit 126 x 2763 SCI CAL 9 1 0 x11 slit 251 x 2763 SCI CAL 7 2 2 VIS Table 72 full description of the VIS slit mask Position Size Physcal size um Purpose 1 0 5 pinhole 131 hole CAL 2 5 x11
114. ee Table 5 400k 1 pt lg VIS readout mode SEQ NEXPO UVB 0 100 1 No of UVB exposures SEQ NEXPO VIS 0 100 1 No of VIS exposures Fixed Value INS MODE IFUSPEC SLITSPEC IFUSPEC Instrument Mode INS OPTI3 NAME see Table 4 1 0x12 6 UVB slit INS OPTI4 NAME see Table 7 1 0x12 6 VIS slit Table 51 User and fixed keywords for XSHOOT ER slt cal NIRArcs XSHOOTER_ifu_cal_NIRArcs Free Parameters Keyword Range Default Value Label in P2PP DET3 DIT 0 36000 1 32 NIR Exposure Time DET3 NDIT 1 20 1 Number of DITs SEQ NEXPO 0 100 1 No of NIR exposures Fixed Value INS MODE IFUSPEC SLITSPEC IFUSPEC Instrument Mode INS OPTI5 NAME see Table 8 1 0x12 6 NIR slit Flatfield pixel response orders localization Table 52 User and fixed keywords for XSHOOT ER slt cal UBVLampFlat XSHOOTER_slit_cal_UVBLampFlat Free Paramters Keyword Range Default Value Label in P2PP INS OPTI3 NAME see Table 4 1 0x11 UVB slit DET1 READ CLKDESCR_ see Table 5 100k 1pt hg UVB readout mode DET1 WIN1 UIT1 HIGHF 0 36000 7 4 Halogen lamp exposure time DET1 WIN1 UIT1 LOWF 0 36000 2 8 D2 lamp exposure time SEQ NEXPO HIGHF 0 100 5 Number of Halogen lamp exp SEQ NEXPO LOWF 0 100 5 Number of D lamp exp Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode ESO Karl Schwarzschild Str 2 8574
115. elluric standards selected from the Hipparcos Catalog Unfortunately hot stars still contain some features usually lines of hydrogen and helium which can be difficult to remove If the regions around the hydrogen and helium lines are of interest then one can also observe a late type star which should have weak hydrogen and helium lines This star is then used to correct for the helium and hydrogen absorption in the ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 111 of 161 spectrum of the hot star Some hot stars also have emission lines or are in dusty regions These stars should be avoided The V I colour of the star can be used as an indicator of dust For stars hotter than AO it should be negative And lastly hot stars tend to lie near the galactic plane so there may be situations where there are no nearby hot stars Solar analogs for the purpose of removing telluric features are stars with spectral type GOV to G4V These standards have many absorption lines in the IR particularly in the J band The features can be removed by dividing by the solar spectrum that has been degraded to the resolution of the observations In addition to hot stars and solar analogs IR astronomers have used other stellar types as telluric standards For example F dwarfs are commonly used Users should think carefully about which star is best for their program Al
116. els 2048x4102 used in 1024x2048 windowed readout used Pixel size 15 um 15um 18um Gain High 0 62 High 0 595 2 12 e ADU Low 1 75 Low 1 4 Readout noise Slow 2 5 Slow 3 1 Short DIT 25 e rms Fast 4 5 Fast 5 2 DIT gt 300s 8 0 Saturation 65000 65000 45000 for a ADU single readout TLI 42000 ADUs used for long DITs Full frame 1x1 slow fast 68 16 1x1 slow fast 89 21 1 46 for a single readout 21 e pix h lt 1 up to 45000 ADUs Table 6 measured properties of the X shooter detectors ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 390f161 2 2 5 The VIS spectrograph 2 2 5 1 Slit carriage The slit carriage of the VIS spectrograph is identical to that of the UVB but the available slits are different All the science observation slits are 11 high and different widths are offered from 0 4 to 5 see Table 7 Table 7 VIS spectrograph slits and calibration masks Size Purpose 0 4 x 11 slit SCI CAL 0 7 x11 slit SCI CAL 0 9 x 11 slit SCI CAL 1 2 x11 slit SCI CAL 1 5 x11 slit SCI CAL 5 0 x11 slit CAL Row of 9 pinholes of 0 5 spaced at 1 4 GAL 0 5 pinhole CAL 2 2 5 2 Optical layout The optical layout of the VIS spectrograph is very similar to that of the UVB see Figure 7 The collimator mirror corrector lens is identical F
117. er of Halo lamp exp SEQ NEXPO LOWF 0 100 5 Number of D2 lamp exp Fixed Value INS MODE IFUSPEC SLITSPEC IFUSPEC Instrument Mode INS OPTI3 NAME see Table 4 1 0x12 6 UVB slit ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 148 of 161 Table 56 User and fixed keywords for XSHOOTER ifu cal VISLampFlat XSHOOTER_ifu_cal_ViSLampFlat Free Paramters Keyword Range Default Value Label in P2PP DET2 WIN1 UIT1 0 36000 12 2 VIS Exposure Time DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode SEQ NEXPO 0 100 5 VIS No of exposure Fixed Value INS MODE IFUSPEC SLITSPEC IFUSPEC Instrument Mode INS OPTI4 NAME see Table 7 1 0x12 6 VIS slit Table 57 User and fixed keywords for XSHOOTER ifu cal NIRLampFlat XSHOOTER_ifu_cal_NIRLampFlat Free Parameters Keyword Range Default Value Label in P2PP DET3 DIT 0 36000 60 NIR exposure time DET3 NDIT 1 20 1 Number of DITs SEQ NEXPO 0 100 5 NIR No of exposures Fixed Value INS MODE IFUSPEC SLITSPEC IFUSPEC Instrument Mode INS OPTI5 NAME see Table 8 1 0x12 6 NIR slit ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 149 of 161 Format check 1 guess of w
118. era re images the chellogramme onto the detector at f 2 1 plate scale 12 1 mm ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 48 of 161 2 2 6 5 Detector The NIR detector is a Teledyne substrate removed HgCdTe 2kx2k 18um pixel Hawaii 2RG from of which only 1kx2k is used It is operated at 81K Measured characteristics and performances are given in Table 6 Sample up the ramp non destructive readout is always used This means that during integration the detector is continuously read out without resetting it and counts in each pixel are computed by fitting the slope of the signal vs time In addition Threshold Limited Integration TLI mode is used to extend the dynamical range for long exposure times if one pixel is illuminated by a bright source and reaches an absolute value above a certain threshold close to detector saturation only detector readouts before the threshold is reached are used to compute the slope and the counts written in the FITS image for this pixel are extrapolated to the entire exposure time see Finger et al 2008 Proc SPIE Vol 7021 for a more detailed description Signal SIG EXT LEVEL 8 SIG1 m DIT Figure 9 Extrapolation threshold for nondestructive sampling and extrapolation of detector signal for high flux levels For pixels with high flux red only readout values below EXTLEVEL orange rectan
119. es 1 9 12 13 16 72 New tables 3 4 10 CMa sections 2 4 7 and 2 4 8 2 4 9 4 4 4 7 4 8 added Sections 2 2 1 3 2 4 5 2 46 5 1 1 5 1 2 modified Figure added in 5 1 1 Table 11 updated old Table 3 removed modified structure of the sections CMa update wrt the performances new identified problems and status description of the current ones New items in the FAQ new calibration plan new section about the observation strategy Figures updated to be more clear and useful NIR 1 5 slit removed Intervention of July 2011 briefly described additional corrections of figures and sections according to IOT comments Very minor changes New templates added minor corrections CMa major modifications wrt the new slits in the NIR new slits with K band blocking filter added and background performances the new TCCD performances the new calibration plan correction of typos and clarification of different points attached calibrations known problems etc weblinks modified Modifications regarding phase2 changes for the acquisition setuptreadout wiping overheads additional information regarding integration times for the TCCD ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany 90 91 20 02 2012 03 04 2012 08 08 2012 09 10 2012 Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 5 of 161 Modified sections 2 2 1 4 2 2 4
120. ey are computed as follows the offset RA corresponds to delta RA xcos DEC and the offset DEC is the difference delta DEC 3 4 6 Generic offset SLIT and IFU These are the most flexible observing templates XSHOOTER slt _ obs GenericOffset and XSHOOTER ifu_obs GenericOffset allow the user to define any pattern by providing a list of cumulative telescope offsets This is particularly useful in case one wants to map an object with several slit or IFU positons The number of exposures taken at each position and the exposure time both identical at all positions have to be defined Exposures are asynchronous See also Orientation and conventions However the number of sky and object positions must be the same This is as well the case for the exposure times Mapping SLIT It is important to note that the offsets in all templates are offsets on sky as in other Paranal instruments They are computed as follows the offset RA corresponds to delta RA xcos DEC and the offset DEC is the difference delta DEC 3 4 7 Mapping SLIT and IFU templates In P96 2 new templates called mapping in SLIT and IFU modes will allow the user to define any pattern by providing a list of cumulative telescope offsets This is particularly useful in case one wants to map an object with several slit or IFU positons The number of exposures taken at each position and the exposure time has to be defined Exposures are asynchro
121. fficiency of XSHOOTER with disabled ADCs 2 4 14 Drift of acquisition reference positions It has been recently found 12 2013 a drift of the acquisition reference positions on XSHOOTER All acquisitions are performed blindly not possible to see the slits and the reference positions for the acquisitions were defined for all filters However it appears that a function is drifting leading to a drift of those reference positions This is now monitored and rectified when the drift reaches a significant amount possibly leading to flux losses for the narrower slits Unfortunately a bad software update may have generated losses during the period 12 2013 06 2014 for the observations using narrow slits and the U band acquisition filter 2 4 15 Historical wavelength shift between arms It was reported some shift in wavelength between the arms especially between the VIS and NIR arms This problem was related to two different issues The first one was related to the drift of the acquisition reference positions see section 2 4 14 The second one was related to an error in the AFC recipe of the pipeline Both problems were corrected and the remaining errors are now supposedly consistent with the radial velocity accuracy section 2 4 9 A new document describes those effects and the results after correcting actions taken It is available at https www eso org sci facilities paranal instruments xshooter doc XS _wic_shift_150615 pdf 2 4 16 TCCD featu
122. focus with wavelength The back focal length is rather sensitive to temperature changes It varies by 22 7um C which corresponds to a defocus of 9Qum C or 0 08 C This is automatically compensated at the beginning of every exposure by moving the triplet doublet of the camera by 10 9um C ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany 2 2 4 3 Detector The UVB detector is a 2048x4102 15um pixel CCD from E2V type CCD44 82 of which only a 1800x3000 pixels window is used The CCD cryostat is attached to the camera with the last optical element acting as a window The operating temperature is 153K The CCD control system is a standard ESO FIERA controller shared with the VIS CCD The list of Doc Issue Date Page VLT MAN ESO 14650 4942 P97 19 08 2015 37 of 161 readout modes offered for science observations is given in Table 5 Table 5 List of detector readout modes offered for science observations The 2x2 binning is not recommended whenever a good inter order background subtraction is required see also section 2 4 5 Readout mode Gain e ADU Speed Binning name UVB VIS kpix s Spatial dir Dispersion dir 100k 1pt hg 1 1 100K 1pt ng 1x2 eos te 1 2 100k 1pt hg 2x2 2 2 400k 1pt lg Low Low Fast 1 1 400k 1pt lg 1x2 1 75 1 4 400 1 2 400k 1pt lg 2x2 2 2 One more readout mode 1000x1000 window low gain fast rea
123. gles are taken into account in the calculation of the slope and values written in the FITS files are extrapolated to the full DIT SIG2 For low flux pixels blue all nondestructive readouts are used light blue rectangles Modified figure coming from Finger at al 2008 Note that for operational reasons only a limited number of DITs is offered to the user in case of exposures longer than 300s see section 3 4 1 3 Important Warning adjacent pixels can follow different regimes by using this readout mode one can follow the normal regime and its neighbor can follow and extrapolated regime if the counts reach the extrapolation threshold This may lead to bad line profile and then to affect for example the chemical abundances determination etc Therefore we strongly recommend doing as short as possible DIT and that the counts never reached 89000e or 42000 ADUs in the ETC meaning that the count will not be extrapolated A document explaining in details this readout mode and its different regimes with their consequences is available at http www eso org sci facilities paranal instruments xshooter doc reportNDreadoutpublic pdf ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 49 of 161 Red orders I nal UVB arm Blue un 4 ann gonna wi m Mi INN a a u nn UHREN m ee Tin a ME 0 000M LAN Blue orders
124. he spectrograph flexures with respect to the WAVE calibration at daytime ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 115 of 161 e What is the frequency of the AFC After 1h 1h15mn it is necessary to do the measurements and correct the instrument flexures Only the backbone flexures are actually measured not the internal spectrograph flexures One can add between science templates the new templates SLIT or IFU AFC for doing the measurements and the flexure correction without the need to re acquire the object useful in case of long OB with slit position angle fixed by the user e Does the slit follow the parallactic angle during an exposure For the moment the parallactic angle is only computed during the acquisition preset step and the angle of the rotator set at that time Thus the observations will start at the parallactic angle and the slit position angle on sky will remain fixed during the integration i e not following the parallactic angle e How can I find the slit object position in the acquisition image FITS header keywords HIERARCH ESO SEQ AG XCEN and YCEN record the location of the centre of the SLIT or IFU in the image e Which airmass should specify for the IFU observations Because the ADCs are not used in IFU mode one should consider not to use a large airmass Typically the airmass should be better than 1 5 However the tip
125. his temporary increase this detector remains the best acquisition detector at Paranal eCalibration plan and observing strategies a Imaging mode acquisition and exposure times A basic imaging observing block OB consists of a slit or IFU acquisition template followed by science and or calibration imaging templates However pure imaging OBs are approved only in visitor mode Exceptions in service mode are observations of standard fields for zeropoint determination or distortion maps In service mode OBs can contain imaging templates in addition to the standard slit or IFU science spectral templates There is no ETC support for the imaging mode We recommend to scale the exposures times using the limiting magnitudes listed in Table 3 These magnitudes were obtained under relatively bad weather conditions thin cirrus full Moon seeing about 0 7 Table 4bis Recommended exposure times for the A amp G CCD S N gt 5 V mag 6 7 16 20 23 224 Exposure time s 0 001 0 005 1 5 60 120 2180 b Observing strategies Two science templates are offered 1 XSHOOTER_img_obs STARE mode observation i e the object stays on the same detector pixel 2 XSHOOTER_img_obs_GenericOffset GENERIC OFFSET mode observations i e mapping or jittering around the area of interest Table 5bis Imaging science templates Templates esau speed List of filters Angles and binning STARE Fast read
126. in P2PP Free Parameters INS OPTI3 NAME see Table 4 1 0x11 UVB slit INS OPTI4 NAME see Table 7 0 9x11 VIS slit DET1 WIN1 UIT1 0 36000 30 UVB exposure time DET1 READ CLKDESCR see Table 5 400 1pt lg UVB readout mode DET2 WIN1 UIT1 0 36000 5 VIS exposure time DET2 READ CLKDESCR see Table 5 400 1pt lg VIS readout mode SEQ NEXPO UVB 0 100 1 No of UVB exposures SEQ NEXPO VIS 0 100 1 No of VIS exposures Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode Table 49 User and fixed keywords for XSHOOTER slt cal NIRArcs XSHOOTER sit_cal_NIRArcs Free Parameters Keyword Range Default Value Label in P2PP INS OPTI5 NAME see Table 8 0 9x11 NIR Slit slide DET3 DIT 0 36000 0 66 NIR Exposure Time DET3 NDIT 1420 1 Number of DITs SEQ NEXPO 0 100 1 No of NIR exposures Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Table 50 User and fixed keywords for XSHOOT Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 146 of 161 ER ifu cal UVBVisArcs XSHOOTER_ifu_cal_UVBVisArcs Free Parameters Keyword Range Default Value Label in P2PP DET1 WIN1 UIT1 0 36000 45 UVB Exposure Time DET1 READ CLKDESCR see Table 5 400k 1pt lg UVB readout mode DET2 WIN1 UIT1 0 36000 4 VIS Exposure Time DET2 READ CLKDESCR s
127. in blue orders 1 9 with the 470nm tracking wavelength and lower in the red orders 0 6 compared to the 850nm tracking wavelength This is the same evolution for the VIS arm ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 31 of 161 f Comparison of observations efficiency between airmasses and slit angles In the following table the efficiency is compared between airmass 1 51 and 1 10 flux ratio AM 1 51 AM 1 10 arm Slit angle average range std UVB Parallactic 0 89 0 43 1 0 0 16 UVB Parall 45 0 81 0 59 0 95 0 12 UVB Parall 90 0 68 0 30 1 0 0 24 VIS Parallactic 0 92 0 82 1 0 0 05 VIS Parall 45 0 81 0 70 0 98 0 09 VIS Parall 90 0 66 0 42 1 0 0 18 g Airmass constraints for observations To help in the process of observation preparation below is a plot from VIMOS MOS mode showing the airmass limit depending of the target declination for an observation at 2h of the meridian ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 32 of 161 VIMOS airmass constraint for MOS OBs airmass lt 1 0 7870 c0 8 0 4173 sin Stay in the shaded area when specifying your airmass constraint Maximum allowed airmass Target declination 5 At the Cassegrain focus there is no possibility ye
128. is mode could eventually be offered to the community manpower and time dependent Some results are available in the news page of XSHOOTER ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc Issue P97 Date 19 08 2015 Page 17 of 161 VLT MAN ESO 14650 4942 2 Technical description of the instrument Calibration unit Th Ar D lamps Q EIVI instrument shutter 4 LN calibration mirrors IFU Ar KrNeXe lamps FF lamps AES VY HH N 9 acq pin mon 50 50 A amp G 3 positions mirror pellicle filter wheel exposure VIS slit Te i shutter carriage A UV slit exposure u G N carriage shutter VIS f spectro w COLD A NIRslit wheel NIR spectro Figure 2 Schematic overview of X shooter a spectro ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 18 of 161 2 1 Overview of the opto mechanical design Figure 2 shows a schematic view of the layout of the instrument It consists of four main components e The backbone which is directly mounted on the Cassegrain derotator of the telescope It contains all pre slit optics the calibration unit a slide with the 3 positions mirror and the IFU the acquisition and guiding camera the dichroic box which splits the light between the three arms one piezo tip tilt mirror for each arm to allow active compensation of backbone flexures a
129. it with filter despite a strong decrease of the RON For DIT longer than 1000s the background is sly limited at least at the 1682nm b For normal 0 9 slit without filter For this slit the background is RON limited for DIT up to 200s 300s at wavelengths 1682nm and 1300nm Then for longer DIT the background is sky limited Noise contributions as a function of DIT for a 0 9 slit darktime 25 RON Dark current with filter 1048nm without filter 1048nm ssssssesseee with filter 1238nm 20 without filler 1238nm s 1 with filter 1300nm without filter 1300nm H H 4 4 with filter 1682 nm without filter 1682nm vesseseereee Noise e rms A gi _ oO 1 10 100 1000 DIT s ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Noise e rms Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 46 of 161 B Backgrounds with 0 6 slits with without filters a For 0 6 slit with K band blocking filter Unfortunately the background is always RON limited b For normal 0 6 slit without filter For this slit the background is RON limited for DIT up to 360s at wavelength 1682nm and 450s at 1300nm Then for longer DIT the background is sky limited Noise contributions as a function of DIT for a 0 6 slit darktime 25 RON Dark current with filter 1048nm without filter 1048nm sssesssseee with filter 1238nm 20 without
130. ithout performing them mode J ql BERRA for HELP 5 Stack the science images WCS based use swarp It is possible to use the IRAF tasks imstack or imcombine to combine the science images However it has been shown that IRAF does not always properly handle large images or the WCS Therefore we recommend to use the swarp software from astromatic ex TERAPIX from E Bertin http www astromatic net software swarp Syntax swarp liste_files_images c configuration_file the configuration_file contains all the parameters needed for the creation of the mosaic taking into account the WCS and recomputing it In the file liste_files_images list all images that are needed for the mosaic ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 100 of 161 5 Instrument and telescope overheads 5 1 1 Summary of telescope and instrument overheads Table 14 overheads Acquisition and setup Telescope pointing guide star acquisition 360s start active optics X shooter backbone flexure measurement Interactive acquisition loop See a SLIT see b Instrument setup at the end of acquisition IFUs see b Delay of start of exposures see c Observations 1x1 slow fast 68s 16s UVB 1x2 slow fast 34s 8s 2x2 slow fast 17s 4s Detector readout 1x1 slow fast 89s 21s See also
131. itude for a S N 10 no binning 1 h exposure airmass 1 2 0 8 seeing slits of 1 0 in UVB 0 9 in VIS and NIR arms ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 550f161 2 4 Instrument features and known problems to be aware of 2 4 1 UVB and VIS detectors sequential readout UVB and VIS detectors share the same FIERA controller While both arms can expose simultaneously readout is done sequentially In practice this means that if an exposure finishes in one of the arms while the other one is being read out the shutter of the second arm is closed but readout is delayed until data from the first arm are fully transferred to disk See also Sect 3 5 5 which gives advices on how to use reduce the dead time corresponding to this sequential readout 2 4 2 Effects of atmospheric dispersion In IFU mode there is no correction for atmospheric dispersion see sections 3 4 1 2 2 2 Unfortunately due to ADCs problem they were disabled on August 1 2012 and therefore the slit observations are now performed with disabled ADCs See section 2 2 2 for information about the performances without ADCs and the atmospheric effect 2 4 3 Remanence After a few months of operation it has been verified that long DITs namely 1800s DITs in the NIR arm especially when used continuously during the night leave significant remnants by the thermal backgr
132. ixed Value ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 152 of 161 Table 68 User and fixed keywords for XSHOOTER_gen_cal_DarkUVBVIS template This template allows to run biases for the UVB VIS arms simultaneously of darks in the NIR arm XSHOOTER_gen_cal_DarkUVBVis tsf To be specified DET1 WIN1 UIT1 DET2 READ CLKDESCR DET2 WIN1 UIT1 SEQ NEXPO UVB SEQ NEXPO VIS 100k 1pt hg 100k 1pt hg 2x2 400k 1pt lg 1x2 100k Ipt hg 0 36000 3600 100k 1pt hg 100k 1pt hg 2x2 400k 1pt lg 1x2 100k Ipt hg 0 36000 3600 0 500 1 0 500 2 100k 1pt hg 1x2 400k 1 pt lg 400k 1pt lg 2x2 100k 1pt hg 1x2 400k Ipt lg 400k Ipt lg 2x2 UVB Exposure time VIS readout mode VIS Exposure time Number of exposures for UVB det NEXP Number of exposures for VIS det Parameter in Vale Label Table 69 New multi order definition template XSHOOTER_slt_cal_MultipleOrderDef running for multi pinholes with FF lamps and giving order definition for each pinhole of the row XSHOOTER slit_cal_MultipleOrderDef tsf To be specified Range Dafal DET1 READ CLKDESCR DET1 WIN1 UIT1 HIGHF DET1 WIN1 UIT1 LOWF DET2 READ CLKDESCR DET2 WIN1 UIT1 DET3 DIT DET3 NDIT DPR CATG DPR TECH DPR TYPE SEQ NEXPO HIGHF SEQ NEXPO LOWF SEQ NEXPO NIR SEQ NEXPO VIS Fixed values INS MODE INS OPTB NAME INS OPTI
133. ld Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 157 of 161 Science STARE imaging observation XSHOOTER_img_obs tsf To be specified 0 36000 7 TCCD Exposure time siah i ee no SCIENCE Data Prod Cath DPR TECH no IMAGE Data Prod Tech DPR TYPE no OBJECT Data Prod Type INS FILT1 NAME no u_prime g_prime r_prime i_prime z_prime U B V R I V G Filter SEQ NEXPO no 0 1000 7 Number of exposures meter H n Value La Science Generic OFFSET imaging observation XSHOOTER_ mg_obs_GenericOffset tsf To be specified iden T Range ep TE ______ DET4 WIN1 UITI 0 36000 7 TCCD Exposure time DPR CATG yes SCIENCE Data Prod Cath DPR TECH yes IMAGE Data Prod Tech DPR TYPE yes OBJECT OFFSET Data Prod Type INS FILT1 NAME no u_prime g_prime r_prime i_prime z_prime UB V R I V G Filter SEQ NEXPO no 0 100 Number of exposures SEQ NOFFSET no 1 100 2 Number of offsets SEQ OBS TYPE no OS List of TYPE offsets e g OS SO SEQ OFFSET COORDS no SKY DETECTOR SKY Oki coord type RA DEC X Y SEQ OFFSET ZERO no TF M Go to zero offset position at the end SEQ RELOFFI no 1000 1000 7 List of RA X offsets SEQ RELOFF2 no 1000 1000 7 List of DEC Y offsets arameter H n Value ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 158 of 161 C
134. le imaging mode with limited functionalities is offered to the community starting in P93 The imaging mode uses the 4 arm of X shooter that corresponds to the Acquisition and Guiding A amp G camera and its set of filters Acquisition images have already been used in past periods to obtain reference photometry to flux calibrate spectra in addition to the usual spectrophotometric observations Other applications have been the determination of magnitudes of transient objects such as GRB counterparts supernovae and variable objects e g stellar binaries and stars with exoplanets With the implementation of the imaging mode in P93 only one acquisition snapshot is saved and not after each applied offset as was previously the case For direct target acquisition one snapshot will be saved once the acquisition process is finished In case of a target acquisition using a blind offset one snapshot will be saved at the end of the acquisition of the reference star and one after the blind offset is performed eDetector characteristics filters and zeropoints The A amp G unit consists of eA Pelletier cooled 13 um pixel 512x512 E2V broad band coated Technical CCD57 10 onto which the focal plane is re imaged at f 1 91 through a focal reducer This setup provides a plate scale of 0 174 pix and a field of view of 1 47 x1 47 eA filter wheel equipped with a full UBVRI Johnson filter set and a full Sloan Digital Sky Survey SDSS filter set
135. leaves remnants see section 2 4 3 However the minimum DIT is 0 66s The use of the NDIT different than 1 will give one averaged exposure internally of the DIT integrations The pre processor of the system is averaging internally the NDIT individual DIT integrations The number of counts will only correspond to DIT but the noise will be reduced ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 760f161 Example NDIT 2 DIT 100s NINT 1 will give 1 averaged exposure The total integration time will be of 200s NDIT 1 DIT 100s NINT 2 will give 2 exposures of 100s each The total integration time will be of 200s NDIT 2 DIT 100s NINT 2 will give 2 averaged exposures The total integration time will be of 400s NDIT 1 should be used in most cases 3 4 2 Staring SLIT and IFU With the XSHOOTER slt_obs_ Stare and XSHOOTER ifu_obs_ Stare templates one or more spectra are taken with each arm independently at a fixed position on sky For each arm the user chooses the exposure time and the number of exposures Exposures are completely asynchronous i e in each arm whenever an exposure is finished the next one starts immediately independently of what is happening with the other arms 3 4 3 Staring synchronized SLIT and IFU Whenever exposures in the three arms have to be parallel the templates XSHOOTER slt _ obs StareSynchro or XSHOO
136. lination of the target One can see that for HA 2 the values correspond to those reported in the figure above for VIMOS ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 34 of 161 Airmass variation From this plot about the airmass variation one can see that for declination 40 degrees the airmass will change from AM 2 4 to 2 5 in 1h so a relative small change but it means for the UVB arm a dispersion between the blue and red orders of about 5 while the parallactic angle will change by 110 degrees in 1 h As a consequence for such observation it is recommended to do short exposures and do some re acquisitions to setup frequently the slit at the parallactic angle If it is not performed after few minutes the main dispersion direction will imply that some orders will be missed For declination 50 degrees in 1h 1 HA the airmass will change from AM 1 12 to 1 13 therefore the dispersion for the UVB arm between the blue and red orders is about 1 while the parallactic angle changes by 35 degrees It means that the orders at the border will be affected by flux losses but less important that in the case of the declination 40 degrees In case of large dispersion it could be better to use the stare mode with the parallactic angle and with short OBs or to use the nodding with a smaller nodding throw by default 5 ESO Karl Schwarzschil
137. lso very low level pattern with a deviation from the background level of 1 Figures are available at http www eso org observing dfo quality XSHOOTER gc problems problems_xshooter html In the slow readout mode the pick up noise is lower and the patterns are not seen 2 4 12 NIR IFU parasitic reflections In the IFU mode some reflections of small irregularities of the edges of the IFU mirrors can be visible in the images However they are faint and should not affect the observations An example is shown below in Figure 16 with an IFU flat field ee Figure 16 Example of small irregularities of the edges of the IFU mirrors in the NIR arm ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 63 of 161 2 4 13 UVB VIS ADCs problem UVB VIS ADCs intermittently show initialization problems especially in cold conditions Since August 2010 a new operational procedure has been implemented to prevent starting science observations with the UVB VIS ADCs in a wrong position In the evening at the time of the instrument startup and during the morning calibrations the ADCs are closely monitored to ensure that the systems are working as expected Unfortunately the ADCs failed more and more frequently between March and July 2012 and it has been necessary to disable them since August 1 2012 See section 2 2 2 for the relevant information about the e
138. m stare to nodding mode would increase by 25 this time spent In P91 the slit telluric standard stars observations will be performed in nodding mode but with the fast readout modes in UVB VIS arms irrespective to the readout speed used in the science OB The binning will match the one of the science OB Such kind of change should increase by about 10 the time spent on telluric standard stars observations However despite the use of the fast readout modes the SNR will not be dramatically modified and the telluric sky background and bad pixels corrections will be improved This modification in the strategy of the telluric standard stars observations is mostly relevant for the bright objects Starting with P93 a new software tool is available to correct the telluric lines It is reachable at http www eso org sci software pipelines skytools 3 5 4 Observing bright objects limiting magnitudes and the diaphragm mode With respect to the previous periods it was found that some of the proposed objects are too bright for doing their observation with XSHOOTER In particular do not forget that the minimum DIT in the infrared is 0 66s this means that no DIT lower than 0 66s exist and the IRACE controller will transform DIT shorter than 0 66s to 0 66s integration ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 83 of 161 According to the ETC and me
139. ma 3 Upper sigma clipping factor rdnoise 0 cedclip CCD readout noise electrons gain 1 cedelip CCD gain electrons D snoise 0 cedclip Sensitivity noise fraction sigscal 0 1 Tolerance for sigma clipping scaling corrections fpcelip 0 5 pclip Percentile clipping parameter grow 0 Radius pixels for neighbor rejection mode ql gt Eu for HELP ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 990f161 2 Optionally create the masterdark Same than 1 for combining the images 3 Create the masterflatfield Same than 1 for combining the images eDetermine the count level with the IRAF imstat task eNormalize the image with the imarith task to obtain the master flatfield 4 Correct the science images for bias dark and flatfield eUse the imarith task A WG cmarayan nb015045 duties xshooter moveUT2 Image Reduction and Analysis Facility PACKAGE imutil TASK imarith operandi sciencel fits Operand image or numerical constant op Operator operand2 masterbias fits Operand image or numerical constant result Resultant image title Title for resultant image divzero 0 Replacement value for division by zero hparams List of header parameters pixtype Pixel type for resultant image calctyp Calculation data type verbose no Print operations noact no Print operations w
140. many Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 113 of 161 6 7 The X shooter pipeline A new X shooter pipeline gt v2 5 5 will be released soon fixing some bugs and improving the flexures correction and wavelength calibration The X shooter pipeline v2 2 0 has been recently released with its REFLEX support With REFLEX several recipes are user interactive with displayed plots allowing checking the results on the fly and re running the recipes with modified parameter values It is available at http www eso org sci software pipelines It supports both instrument modes SLIT and IFU e It delivers the sky subtracted or not cosmic ray hits cleaned flux and wavelength calibrated 2D spectra rectified to a regular grid in wavelength and spatial directions 1D extracted spectra is produced whenever a bright enough object is detected It is also possible to specify a region where the spectra have to be located and treated For example in case of 2 objects inside the slit the extraction can be performed for both objects using different boxes of research e 3D reconstructed data cubes will be produced for IFU data e Additional products to verify the quality of the results and a set of Quality Control parameters instrument health check and trend analysis Some of the functionalities are still in development more information is available in the pipeline user manual and in the website of the pipelines at http ww
141. n dest STARE 9999 parallactic UVBRI angle IMAGING GENERIC OFFSET oo UGRIZ or choose another value Table 13 Instrument setup summary ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 80of 161 3 5 2 Observation strategy This section provides basic information for the observations To better specify the strategy of your observations you should contact usd help eso org SM and VM or discuss it with the Paranal day night astronomers in VM In all cases you can choose different kind of observing modes see Sect 3 5 1 and different slits on the different arms if no IFU after the acquisition template For example you can do SLIT acquisition SLIT STARE SLIT NODDING e Point source object Usually if your object is a point source like the slit spectroscopic observation is the best In such case select the SLIT instrument mode If the infrared observations are critical the NODDING mode is preferable than the other ones because it will allow to better correcting the sky emission lines and the sky variation In case the NIR observation is not so critical the use of the STARE mode is OK The object will stay in the same position of the slit This mode corresponds to the usual observing mode with other optical instrument as UVES Select a slit of about 0 9 1 if you want to match the slit with the median seeing a
142. nous See also Orientation and conventions Those templates allow different number of exposures on sky or object positions It is important to note that the offsets in all templates are offsets on sky as in other Paranal instruments They are computed as follows the offset RA corresponds to delta RA xcos DEC and the offset DEC is the difference delta DEC ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 79 of 161 3 5 Observation strategy summary and tricks 3 5 1 Instrument setup Instrument Observing mode Readout binning Slits filters PA mode UVB 100k 1x1 STARE UVB 100k 1x2 UVB 100k 2x2 NODDING UVB 400k 1x1 UVB UVB 400k 1x2 0 5 0 8 1 0 1 3 1 6 5 9999 parallactic SLIT RRM FIXED OFFSET UVB 400k 2x2 VIS angle or normal VIS 100k 1x1 0 4 0 7 0 9 1 2 1 5 5 rehoose another GENERIC OFFSET VIS 100k 1x2 NIR value VIS 100k 2x2 0 4 0 6 0 9 1 2 5 blind SYNCHRONIZED VIS 400k 1x1 0 6 JH 0 9 JH ETC VIS 400k 1x2 VIS 400k 2x2 NIR non dest STARE UVB 100k 1x1 UVB 100k 1x2 FIXED OFFSET UVB 100k 2x2 UVB 400k 1x1 GENERIC OFFSET UVB 400k 1x2 9999 parallactic IFU RRM ce en IFU 1 0 x12 6 fixed in angle or normal SYNCHRONIZED VIS 100K 1x2 each arm or choose another ETC VIS 100k 2x2 value VIS 400k 1x1 VIS 400k 1x2 VIS 400k 2x2 NIR no
143. nsmission Transmission 650 700 750 800 850 900 700 800 900 1000 1100 Wavelength nm Wavelength nm Table 2bis A amp G CCD zeropoints U B V R fee ee N 24 94 27 27 27 20 27 13 26 73 11 Bi a 565 24 83 27 91 27 83 27 74 27 36 a oa j 24 95 27 74 27 63 27 83 27 49 ZP FORS2 2011 24 31 27 68 28 09 28 32 27 67 Note The A amp G CCD zeropoints were determined for the Johnson filters under photometric condition The accuracy of the ZP X shooter magnitudes is about 0 05 0 1 magnitude depending on the filters FORS2 zeropoints are provided for comparison ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 90 0f 161 Stability of the AGCCD The stability of the imaging mode and the AG CCD detector was investigated Short medium and long term stability aspects were tested a The spectrophotometric standard star GD71 was monitored over 1 hour with exposures every few seconds The 1 s standard deviation in B and V bands are 0 006 magnitude for both band It represents a variation of 0 4 b The stability at medium term was checked with the evolution of the bias and readout noise levels They are shown below Over a period of 52 days the RMS of the bias level variability is 0 33 and for the RON it is 0 56 a bias e ron bias 1c bias 1o 15 RON Ie
144. nt Mode ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Table 41 Parameters for the template XSHOOT Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 141 of 161 ER slt cal UVBLampFlatAtt XSHOOTER _sit_cal_UVBLampFlatAtt Keyword Range Default Value Label in P2PP Free Parameters DET1 WIN1 UIT1 HIGHF 0 36000 UVB exposure time High Flat DET1 WIN1 UIT1 LOWF 0 36000 UVB exposure time Low Flat DET2 READ CLKDESCR see Table 5 VIS readout mode SEQ NEXPO HIGHF 0 100 No of exposures High Flat SEQ NEXPO LOWF 0 100 No of exposures Low Flat Fixed Value INS MODE IFUSPEC SLITSPEC SLTSPEC Instrument Mode Table 42 Parameters for the template XSHOOT ER slt cal VISLampFlatAtt XSHOOTER _slit_cal_ViSLampFlatAtt Keyword Range Default Value Label in P2PP Free Parameters DET2 WIN1 UIT1 0 36000 VIS exposure time DET2 READ CLKDESCR_ see Table 5 VIS readout mode SEQ NEXPO 0 100 No of exposures Fixed Value INS MODE IFUSPEC SLITSPEC SLITSPEC Instrument Mode Table 43 Parameters for the template XSHOOT ER slt cal VISLampFlatAtt XSHOOTER_slt_cal_NIRLampFlatAtt Keyword Range Default Value Label in P2PP Free Parameters DET3 DIT 0 36000 NIR exposure time DIT DET3 NDIT 0 20 No of NIR sub integrati
145. of the atmospheric dispersion range for the NIR arm In case of IFU observations one can select the telescope tracking wavelength ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 25 of 161 2 2 1 7 The Focal Reducer and Atmospheric Dispersion Correctors Both UVB and VIS pre slit arms contain a focal reducer and an ADC These focal reducer ADCs consist of two doublets cemented onto two counter rotating double prisms The focal reducers bring the focal ratio from f 13 41 to f 6 5 and provide a measured plate scale at the entrance slit of the spectrographs of 3 91 mm in the UVB and 3 82 mm in the VIS The ADCs compensate for atmospheric dispersion in order to minimize slit losses and allow orienting the slit to any position angle on the sky up to a zenith distance of 60 The zero deviation wavelengths are 405 and 633 nm for the UVB and the VIS ADCs respectively In the AUTO mode their position is updated every 60s based on information taken from the telescope database Unfortunately due to some problems affecting the ADCs they have been disabled since August 1 2012 See the following section for more information about the observations without ADCs The NIR arm is not equipped with an ADC The NIR arm tip tilt mirror compensates for atmospheric refraction between the telescope tracking wavelength 470 nm and 1310 nm which corresponds to the
146. ons SEQ NEXPO 0 100 No of exposures Fixed Value INS MODE IFUSPEC SLITSPEC SLITSPEC Instrument Mode ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Table 44 Parameters for the template XSHOOT Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 142 of 161 ER ifu cal UVBVisArcAtt XSHOOTER_ifu_cal_UVBVisArcsAtt Keyword Range Default Value Label in P2PP Free Parameters DET1 WIN1 UIT1 0 36000 UVB exposure time DET1 READ CLKDESCR see Table 5 UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time DET2 READ CLKDESCR see Table 5 VIS readout mode SEQ NEXPO UVB 0 100 1 No of UVB exposures SEQ NEXPO VIS 0 100 1 No of VIS exposures Fixed Value INS MODE IFUSPEC SLITSPEC IFUSPEC Instrument Mode Table 45 Parameters for the template XSHOOT ER ifu cal UVBVisArcAtt XSHOOTER_ifu_cal_UVBLampFlatAtt Keyword Range Default Value Label in P2PP Free Parameters DET1 WIN1 UIT1 HIGHF 0 36000 UVB exposure time High Flat DET1 WIN1 UIT1 LOWF 0 36000 UVB exposure time Low Flat DET2 READ CLKDESCR see Table 5 VIS readout mode SEQ NEXPO HIGHF 0 100 No of exposures High Flat SEQ NEXPO LOWF 0 100 No of exposures Low Flat Fixed Value INS MODE IFUSPEC SLITSPEC IFUSPEC Instrument Mode Table 46 Parameters for the template XSHOOT
147. or cross dispersion it uses a 49 Schott SF6 prism in double pass The main dispersion is achieved through a 99 4 grooves mm 54 0 blaze chelle grating The off blaze angle is 0 0 and the off plane angle is 2 0 The camera 3 lens groups 1 aspherical surface reimages the cross dispersed spectrum at f 2 8 plate scale 8 98 mm onto the detector not tilted Focusing is obtained by acting on the triplet doublet sub unit of the camera However unlike the UVB arm the back focal length varies less than 1um C image blur lt 0 004 C hence no thermal focus compensation is needed 2 2 5 3 Detector The VIS detector is 2048x4096 15um pixel CCD from MIT LL type CCID 20 Like for the UVB arm the cryostat is attached to the camera with the last optical element acting as a window The operating temperature is 135K It shares its controller with the UVB detector and the same readout modes are available see Table 5 Measured properties and performances are given in Table 6 The shutter system is identical to the UVB one ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 40 of 161 2 2 6 The NIR spectrograph The NIR spectrograph is fully cryogenic It is cooled with a liquid nitrogen bath cryostat and operates at 105 K 2 2 6 1 Pre slit optics and entrance window After the dichroic box and two warm mirrors M1 cylindrical and M2 spheri
148. ormat check 1 guess of wavelength solution eeeeene Order definition 1 guess of order localization cccccccececcescesseseeseesescessereneaeens Arcs multi pinhole 2d wave maps wavelength calibration 442 Detector Calibrations cccccccccseeeeeeeeeeeeeceaaeeeeeeeeeeeeecaaaeaaeeeeeeeeeeeaaaaaaeeeeeeeeeseaaaa 7 1 8 7 2 7 2 1 1 2 2 7 2 3 Imaging mode templates manual ss4s44444HRRnRnnnnnnnnnnnnnnnnnnnnnnnnnnnn Slit TASKS nenne ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 11 of 161 A Figure 1 3D CAD view of the X shooter spectrograph at the Cassegrain focus of one of the VLT Unit Telescopes Table 1 X shooter characteristics and observing capabilities Wavelength range 300 2500 nm split in 3 arms UV blue arm Range 300 550 nm in 12 orders Resolution 5100 1 slit Slit width 0 5 0 8 1 0 1 3 1 6 5 0 Detector 4k x 2k E2V CCD Visual red arm Range 550 1000 nm in 14 orders Resolution 8800 0 9 slit Slit width 0 4 0 7 0 9 1 2 1 5 5 0 Detector 4k x 2k MIT LL CCD Near IR arm Range 1000 2500 nm in 16 orders Resolution 5100 0 9 slit Slit width 0 4 0 6 0 9 1 2 1 5 0 0 6 JH 0 9 JH Detector 2k x 1k Hawaii 2RG Slit length 11 SLIT or 12 6 IF
149. ound in the K band and by the strongest sky emission lines These remnants may still be visible in the morning DARK calibrations and certainly affect the nighttime observations which follow the long exposures For this reason starting from P86 the DIT 1800s is no longer offered Remnants due to the thermal background in the reddest order of the K band has been observed occasionally also with shorter DIT This is currently under discussion and analysis However starting with P90 the DIT of 1800s will be offered again under strong constraints it must be combined with a slit with the K band blocking filter meaning with the 0 6x11JH or 0 9x11JH slits only In this way the remnants coming from the thermal background do not exist the gain by using this long DIT must be highly relevant and has to be justified waiver request the users have to be aware that the remnants from the sky lines could will remain but the spectral format is fixed therefore it should not affect too much the observations However if it is observed during the calibration the presence of remnants especially in dark frames this could lead to forbid again this DIT excepted in VM Even in VM the use of such long DIT is not advisable because of the sky variation and because it leaves strong remnants in the rest of the night and in the calibration frames Remnants have been observed in the three arms also after ThAr calibrations arcs 2D maps or format checks For
150. out UBVRI Seal angle IMAGING GENERIC ad vari or defined angle on OFFSET g Jofa sky It is recommended to use the XSHOOTER_img_obs_GenericOffset template This template results in better correction of the sky background and the dust spots visible in the detector One can define a sequence of small offsets as shown in the following example Offsets are given in arcsec but the reference system can be chosen to be the sky Alpha Delta or X shooter detector coordinate system X Y Offset conventions are illustrated below Templates use cumulative offsets the position at a given time is derived from the sum of all offsets specified so far in the template For example the series of offsets 0 10 0 10 brings the telescope back to the original position for the last exposure ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 92 of 161 c Calibration plan The calibration plan is defined below It may evolve in the next months periods Table 6bis Calibration plan Type of calibration Template Frequency Day bias XSHOOTER_img_cal_Dark 10 daily Day dark XSHOOTER_img_cal_Dark on request 3x10s monthly Day linearity XSHOOTER_img_cal_DetLin monthly Night twilight flats XSHOOTER_img_cal_Flat 10 monthly Night zeropoints XSHOOTER_img_obs_cal_phot once per year or user provided Night distortion map XSHOOTER_img_obs_cal
151. peed for the UVB and VIS arms However the binning for those arms will match the ones of the science frames This would allow to better correct the sky lines variations and the bad pixels Note that the telluric standard star observations are useless for the UVB arm no telluric lines but are useful for the correction of telluric lines present in the VIS and NIR arms It is worth to mention that the Austrian in kind contribution to ESO corresponds to a tool that allows fitting and correcting the telluric lines This tool is available at http www eso org sci software pipelines skytools ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 112 of 161 6 6 2 Absolute flux calibration Spectrophotometric standard stars can be used to obtain the absolute efficiency of the instrument and derive an absolute flux calibration of the science data These observations are done by the Observatory with the wide 5 0 slit with dedicated templates XSHOOTER slt cal StandardStar and XSHOOTER ifu cal StandardStar The use of the 5 is better in order to obtain most of the flux of the specphot standard star Starting from P88 the spectrophotometric standard stars will be observed in nodding mode with a new specific template The classical set of UV optical standard stars from Oke 1990 AJ 99 1621 and Hamuy et al 1994 PASP 106 566 do not cover the whole
152. res The cooling system of the CCD produces small oscillations of the temperature of the CCD around an average Temperature variations affect the dark current level so in case of short exposure times when the image sampling frequency happens to align with the frequency of the temperature oscillations this leads to beats and background level variations from one image to the next one These variations in background level disappear if a longer exposure time is selected In any case they do not affect the acquisition performance In addition since June 2011 the noise was improved and the quality of images allow under good weather conditions to see objects as faint as magnitudes 25 in R V bands in 3mn Due to an upgrade of the VLT software driving all acquisition CCD in January 2014 the snapshots saved during the acquisition process are of sub optimal quality It is worth to note that the imaging mode images are not affected at all by this problem However we recommend to take several exposures to allow the system to cool down the detector and decrease the thermal background usually high in the first exposure and becoming good in the 2 one ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 64 of 161 3 Observing with X shooter 3 1 Observing modes and basic choices Starting in P93 X shooter offers three observing modes SLIT spectroscopy IFU spe
153. rized in Table 1 A Consortium involving institutes from Denmark Italy The Netherlands France and ESO built x shooter Name of the institutes and their respective contributions are given in Table 2 1 3 Shortcuts to most relevant facts for proposal preparation e The fixed spectral format of X shooter see Table 11 on page 50 Table 2 collaborating institutes and their contributions Collaborating institutes Contribution Copenhagen University Backbone unit UVB spectrograph Mechanical Observatory design and FEA Control electronics ESO Project Management and Systems Engineering Detectors final system integration commissioning logistics Data Reduction Software Paris Meudon Observatory Integral Field Unit Data Reduction Software Paris VII University INAF Observatories of Brera UVB and VIS spectrograph Instrument Control Catania Trieste and Palermo Software optomechanical design Astron Universities of NIR spectrograph contribution to Data Amsterdam and Nijmegen Reduction Software Spectral resolution as a function of slit width see Table 12 on page 52 Information on the IFU see Section 2 2 1 3 Information on limiting magnitudes in the continuum see Section 2 3 3 on page 53 Information on observing modes see section 3 1 on page 64 Observing strategy and sky subtraction see Section 3 3 on page 67 Overhead computation see Section 4 on page 84 ESO Karl Schwarzschild Str 2 85748 Garching bei
154. se blind offsets in case the object is fainter than 22 22 5 especially if the weather constraints are selected for thin thick transparency and seeing worse than 0 7 In case of blind offsets we recommend to select an acquisition star with a magnitude about 19 or brighter to ensure a good centering before the offsets are done For other SDSS filters we recommend to keep a limiting magnitude of 20 for a direct acquisition in I and z but to go up to 21 in other SDSS filters The exact limiting magnitudes for those filters will be determined during P93 Examples of recommended exposure times for the acquisition CCD Vmag 6 integration time 0 001s Vmag 7 integration time 0 005s Vmag 16 20 integration time 1 to 5s V R mag 23 integration time 60 120s V R mag gt 24 integration time 180s These integration times should suffice for doing a direct acquisition in case of clear conditions darktime and usual seeing However in case of very faint objects the blind offset could be the best solution as it could shorten the acquisition overheads See Sect 4 about the imaging mode that provides updated information about the AGCCD and the imaging mode facility ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 24 of 161 2 2 1 5 The dichroic box Light is split and distributed to the three arms by two highly efficient dichroic beam splitters These are
155. sets SEQ RELOFF2 1000 1000 0 List of DEC Y offsets SEQ OBS TYPE O S OS List of observation type object or sky SEQ NOFFSET 0 100 2 Number of offsets SEQ OFFSET ZERO T F T Return to Origin Fixed Values INS MODE SLITSPEC SLITSPEC Instrument Mode IFUSPEC SEQ AGSNAPSHOT ME F Take an acquisition image before science exposures The MAPPING template has the same structure than the GENERIC OFFSET template but allows the freedom to have different number of exposures in object sky and a proper automatic data reduction by the pipeline ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany IFU observations Doc Issue Date Page VLT MAN ESO 14650 4942 P97 19 08 2015 129 of 161 Table 27 User defined and fixed parameters for IFU observations in stare mode with the template XSHOOTER ifu obs Stare XSHOOTER_ifu_obs_ Stare Keyword Range Default Value Label in P2PP Free parameters DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXP UVB 0 100 1 UVB number of exposures SEQ NEXP VIS 0 100 1 VIS number of exposures SEQ NEXP NIR 0 100 1 NIR number of exposures Fixed
156. spectral range of X shooter thus making calibration of full spectral range of X shooter problematic To remedy this situation dedicated 2 years observing campaign has been undertaken as an ESO Observatory Programme pro 278 D 5008 to extend to the near IR a subset of 12 standard stars from the two references cited above to the near IR Tabulated fluxes used by the pipeline for those 12 stars from 300 to 2500 nm allow an absolute flux calibration to the 5 10 Details of this programme can be found in Vernet et al Proc SPIE 7016 2008 available on the X shooter web pages Currently 7 spectrophotometric standard stars are available and are fully flux calibrated see http www eso org sci facilities paranal instruments xshooter tools specphot list html However BD 17 4708 a HST standard star was found to be a spectroscopic binary and is now observed only if no other suitable star can be observed If you use the fluxes available in the X shooter pipeline please cite Vernet Kerber Mainieri et al 2010 Highlights of Astronomy Volume 15 p 535 535 and Hamuy et al 1994 PASP 106 566 However with disabled ADCs the flux calibration cannot be as good as it was with enabled ADCs We therefore recommend to the users to use as much as possible the parallactic angle to avoid long OBs and to take into accounts some possible flux losses which vay depending on the observations ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Ger
157. sures then the execution time will be dominated by the UVB VIS couple 5x137 685s gt 601s NIR time ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc Issue Date Page c p2pp check VLT MAN ESO 14650 4942 P97 19 08 2015 103 of 161 In p2pp the algorithm takes into account the different exposure times and their number readout times the acquisition time and the instrument setups Note that there is an extra 5s time between the moment of the UVB VIS arms setup is done and the NIR one is done In P90 an algorithm providing indications about the optimization of the overheads was included We kindly ask the users to report potential improvements or incorrectness of this algorithm ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 104 of 161 6 Calibrating and reducing X shooter data 6 1 X shooter calibration plan The calibration plan has been revised during P86 P87 P88 P89 it is now implemented as indicated below A better follow up of and new long term calibrations have been included A summary of the calibration plan manual is given in Table 15 and 17 Table 15 X shooter calibration plan summary Calibration UVB frames VIS frames NIR frames Frequency Purpose Bias 5 read mode 5 read mode daily Master bias andicheck SCE DIES properties
158. t Paranal 0 8 However if you are interesting in the resolving power select narrower slit At the opposite if you are interesting in the flux calibration select the 5 slits As shown in the example above you can combine in the same OB different templates observing mode One can use the STARE mode with 5 slits for the flux calibration and then move in the next template to the NODDING mode with narrower slits for more accurate spectroscopic investigations e Point source object with bad seeing IFU as image slicer As indicating above the SLIT mode is commonly used for the observation of point source object However in case of faint object or you allow observations of the object with bad seeing the use of the IFU could be appropriate because this is physically an image slicer However the nodding is not possible with such instrument mode and for better sky correction an offset to the sky position FIXED OFFSET mode is required The resolving power is also fixed due to the slits fixed in the IFU observation Another point is that the user has to specify the tracking wavelength because the ADCs are in OFF position ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 81 of 161 e Extended object galaxy or crowded field globular cluster In case of an extended object let say a galaxy of 25 in the sky or a star in a huge nebula
159. t count is much lower than without the filter and in all cases the corresponding order is never used for science with those slits ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 59 of 161 e With the 0 6 JH slit some low level interferences are visible in the reddest part of the last order The fringe peak to peak difference accounts for 10 of the level in the worse case They are due to the filter itself However they look stable over the different positions and could be corrected through the flat fields Cuts 1 Pixel Values T 200 Value 5128 1837005615 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 60 of 161 2 4 7 NIR detector interquadrant cross talk and electrical ghosts The XSHOOTER NIR detector as most of infrared detector suffers from an effect called interquadrant cross talk When part of the array is illuminated by a bright object some other parts are activated as well leading to an artificial signal The following link provides a document explaining in details the crosstalk effect http www eso org gfinger hawaii 1Kx1K crosstalk rock crosstalk html In addition to the cross talk effect the XSHOOTER detector as all HAWAII detectors suffers electrical effects leading to electrical ghosts The rea
160. t mode is 100KHz 1x1 for both arms it means that the total time will be UVB or VIS integration readout time of UVB arm readout time of the VIS arm 257s corresponding to 100s of integration time and 157s of readout time To optimize this time then one can do UVB exposure of 100s the readout time is here of 68s therefore the VIS arm can still integrate during 68s more One solution could be to do UVB exposure of 100s VIS exposure of 168s Then the execution time will be VIS exposure time of 168s readout time of VIS arm 257s that is the same time than before but better optimized for science purpose This is a way to decrease the deadtime because we have 168s of integration time and only 89s of readout time In this example the user could also increase without problems the number of NIR exposures from 1 to 4 exposures 4x61 46 246s lt 257s b Example 2 NIR execution time higher than the UVB VIS arms Same kind of observation than in a but the NIR integration time must be of 600s and the readout modes for the UVB VIS are 400khz 1x1 In such case they can optimize the UVB and VIS exposures like this UVB arm t 100s VIS arm t 100s 16s readout time of the UVB arm 116s The execution time for the UVB VIS arms is 116 21 VIS readout time 137s The execution time in the NIR is 600s 1 46s 601 46s In such case the users can decide to take 4 UVB VIS exposures 4x137 548s lt 601s if the user decide to go to 5 UVB VIS expo
161. t the slits are uniformly illuminated ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 110 of 161 6 5 Attached calibrations It is possible to include arc and flat calibration in an observing OB For the selection of offered night time attached calibrations see Table 40 and following However we strongly discourage taking night time attached arcs in the VIS arm SLIT or IFU because of remnants caused by a few strong ThAr lines These remnants persist in the following exposure for up to one hour affecting the subsequent observations Therefore attached VIS arcs can be granted only in visitor mode or in service mode which will be executed only at the very end of the night if possible The user should refer to Table 17 to select the exposure time of the attached calibrations On the UVB side an arc exposure of 6s in the 1x1 binning 3s in the 1x2 binning 1s in the 2x2 binning with the normal readout speed does not produce remnants and should provide enough lines for an accurate radial velocity calibration NOTE the wavelength calibration in the pipeline is not performed with the ARC frames but with the 2dmap frames 9 pinholes ARC lamp The latter provides better results Those calibrations 2dmap are not attached calibrations and it will be possible to add those templates in the science OBs in case you need higher accuracy of wavelength calibrations
162. t to do a secondary guiding Therefore the evolution of the parallactic angle is not followed during the exposures but the slit is setup at the parallactic angle at the moment of the acquisition This angle is followed during the exposure It implies that the atmospheric dispersion direction will change with the time with respect to the slit angle The approximate relative evolution of the parallactic angle post meridian crossing for different hour angles is shown in the following figure for different declinations ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 33 of 161 Relative parallactic angle variation degrees For example the parallactic angle changes by 110 degrees in 1h 1 HA for declination equals to 30 degrees at Paranal For declination 50 degrees in 1h 1 HA the parallactic angle will change by 35 degrees In the case of declination of 30 degrees at the start of the observation the slit angle is set at 0 degree for relative reference and then in less than 1 h the atmospheric dispersion is perpendicular to the slit With the ADCs such evolution was not a problem but without ADCs one has to take this evolution into account and the airmass values its evolution Of course the full dispersion between the blue and the red also depends on the airmass The airmass evolution is shown in the following figure depending on the dec
163. te object and sky observations taking the sky at fixed postion XSHOOTER _slit_ifu_FixedSkyOffset Keyword Range Default Value Label in P2PP Free parameters DET1 WIN1 UIT1 0 36000 UVB exposure time s DET1 READ CLKDESCR see Table 5 100k 1 pt hg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time s DET2 READ CLKDESCR see Table 5 100k 1pt hg VIS readout mode DET3 DIT 0 36000 NIR Detector Integration Time s DET3 NDIT 1 20 1 number of DITs SEQ NEXP UVB 0 100 1 UVB number of exposures per offset position SEQ NEXP VIS 0 100 1 VIS number of exposures per offset position SEQ NEXP NIR 0 100 1 NIR number of exposures per offset position SEQ FIXOFF RA 100 100 0 RA fixed offset SEQ FIXOFF DEC 100 100 0 DEC fixed offset SEQ JITTER WIDTH 0 2 0 Jitter box width in SEQ NABCYCLES 0 100 1 Number OS or SO cycles SEQ OFFSET ZERO TE T Return to Origin Fixed Values INS MODE SLITSPEC IFUSPEC Instrument Mode IFUSPEC INS OPTI3 NAME see Table 4 1x12 6 UVB slit INS OPTI4 NAME see Table 7 1x12 6 VIS slit INS OPTI5 NAME see Table 8 1x12 6 NIR slit SEQ AGSNAPSHOT TE F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Table 30 User defined XSHOOTER ifu_obs GenericOffset S Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 131 of 161 an
164. ted However they do not affect the acquisition performance In June 2011 the noise was improved and the quality of images now allows detecting objects as faint as magnitudes 25 in R and V bands in 3 min exposures and good weather conditions ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Transmission Transmission Transmission Transmission 0 87 gt a ree 04r 0 87 0 67 027 0 87 04r 0 87 0 67 0 27 Chroma Johnson U 320 340 360 380 400 Wavelength nm Chroma Johnson V 500 550 600 650 Wavelength nm Chroma Johnson I 700 800 900 1000 Wavelength nm SDSS g 400 450 500 550 Wavelength nm Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 88 of 161 Figure 3 A amp G camera filter curves 420 700 1100 600 Transmission Transmission Transmission Transmission Chroma Johnson B 1 0 0 8 S a 04 0 2 350 400 450 500 550 600 Wavelength nm Chroma Johnson R 1 0 0 8 0 6 04 0 2 500 600 700 800 900 Wavelength nm SDSS w 10 0 8 0 6 04 0 2 250 300 350 400 450 Wavelength nm SDSS r 10 0 8 0 6 0 4 0 2 500 550 600 650 700 750 Wavelength nm ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 89of161 SDSS i Tra
165. template2 with filter 3 exposures of 1s slit nodding observations stare imaging template3 with filter V They will be useful in case of variable objects like the GRBs The snapshots saved at each position during the acquisition sequence used from P88 to P92 are discontinued in P93 3 5 3 Telluric standard stars and telluric lines correction see also Sect 6 6 1 The user should specify in the README of their observation which kind of telluric standard star is needed for the science observation The telluric standard stars are in P89 as in the previous periods automatically observed in service mode in the Observatory time Currently the telluric standard stars observed by the Observatory should have about 10000 ADUs in the middle of the brightest orders of each arm S N 50 100 If the user needs the observation of a specific star or needs very high signal to noise corresponding calibration OBs should be prepared and submitted The corresponding time will be charged to his her program In addition the Observatory does not provide observations of telluric standard stars with slits of 5 Up to P90 for saving time by default in service mode the telluric standard stars are observed in IFU or SLIT stare mode If the users need other kind of observations they should indicate it in the README or better supply their own OBs The Observatory already spend about 10 of the available time for taking telluric standard stars spectra a change fro
166. this mode will be offered to the community 3 5 5 Readout times in the UVB and VIS arms minimization of overheads Because the UVB and VIS detectors are sharing the same FIERA controller both detectors cannot be read at same time Therefore it may happen that one arm although its exposure is already finished has to wait the end of the read out of the other arm To minimize this dead time one should increase a little bit the exposure time in the UVB or VIS arm Then once the first image is finished and being transferred the other arm is still integrating Then the second image of the remaining arm will be read In addition the VIS arm exposure starts 5s later than the UVB arm and the NIR arm start is delayed by 10s For example if you select a read out in slow unbinned mode and expect to be photon starved in the UVB then according to Table 15 you should make the VIS integration at least 89 s shorter than the UVB one The readout time of the NIR is very short 1s and does not interfere with the UVB and VIS because it is using a different controller IRACE ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 84 of 161 4 The XSHOOTER imaging mode Main contributors C Martayan A Mehner G Beccari E Pena W Hummel A Modigliani A Smette and the X shooter IOT Overview X shooter remains foremost a set of spectrographs but a simp
167. this reason we discourage attached arc calibrations during the night see section 6 4 The optimal exposure time which allows the detection of a sufficient number of lines minimizing the presence of remnants is being discussed During daytime arc exposures are taken last in order to not affect the other calibrations ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 560f161 About the UVB CCD the recent tests show that the detector does not have remnants after arc exposures of 6 to 300s with the 1x1 binning and the normal readout mode 3s exposure in the 1x2 binning for the normal readout mode and 1s exposure for the 2x2 binning in the normal readout mode However it was observed some remnants after the observation during 300s of a very bright star that saturated the UVB detector ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 57 of 161 2 4 4 Ghosts Spurious reflections from the rear surfaces of the dichroics towards the first surface and back again produce a secondary image of the object on the slit that is displaced from its parent by few arcsec and leads to almost in focus ghost spectra in the bottom part of the spectra For a centered object the ghost is located on the edge of the orders but when a bright object is placed on the top part of the slit posi
168. though the Observatory will automatically observe a telluric standard for service programs we cannot guarantee that we will make the best choice as this depends on the science users wish to do If you think that a specific spectral type suits your program better than others we recommend that you submit calibration OBs using the proper calibration templates see sect 7 1 6 in such case the time will be charged to your program or to specify in the readme file of your program what kind of telluric star is needed Currently the telluric standard stars observed by the Observatory should have about 10000 ADUs in the middle of the brightest orders of each arms S N 50 100 The Observatory does not provide observations of telluric standard stars with 5 slits If this S N is not enough for the purpose of your programme as previously we encourage you to submit your own calibration OBs In addition up to P90 the telluric standard star observation is carried out with the stare mode only in SM This already uses 10 of the available time The use of another mode instead of the stare would lead to spend 25 time more in standard star observation or 12 5 of the available time at UT2 Therefore if the user needs nodding mode or IFU offset observations instead of stare observations we encourage him her to submit his her own OBs Starting from P91 the slit telluric standard stars will be observed in nodding mode instead of stare and using the fast readout s
169. tilt are used to correct as much as possible the DAC but cannot replace the ADCs Actually the maximum airmass would depend on the declination of the object One should have a look at section 2 2 2 e A list of previous problems can be found too at http www eso org observing dfo quality XSHOOTER qc problems problems_xshooter html e More information is available at http www eso org sci observing phase2 SMGuidelines FAQP2 html and do not forget to consult the XSHOOTER website in particular the news webpage http www eso org sci facilities paranal instruments xshooter index html e Incase of instrumental question please contact xshooter eso org e In case of questions regarding the phase 1 and phase 2 OB preparation observing strategy please contact usd help eso org ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 116 of 161 7 Reference material 7 1 Templates reference In the following sections all the currently defined X shooter templates are listed with their free and fixed parameters When using the P2PP tool the user has to fill only the fields keywords shown on white background colour in the following tables Keywords shown on gray background colour are fixed within the template itself and can only be modified by the astronomer operating the instrument during the night or during daytime calibration activities 7 1 1 Orientation and
170. tion year TEL TARG ADDVELALPHA 0 0 Additional velocity RA in Is TEL TARG ADDVELDELTA 0 0 Additional velocity DEC in Is TEL TARG OFFSETALPHA 0 0 RA blind offset TEL TARG OFFSETDELTA 0 0 DEC blind offset TEL ROT OFFANGLE 179 99 179 99 9999 IFU position angle on Sky 9999 9999 for parallactic angle INS FILT1 NAME u g r t z U B A amp G filter V R 1 DET4 WIN1 UIT1 0 36000 TCCD exposure time SEQ IFU WLGT 300 2000 470 Wavelength for target centring and tracking TEL AG GUIDESTAR CATALOGUE CATALOGUE Telescope guide star SETUPFILE selection mode NONE TEL GS1 ALPHA 0 0 Guide Star RA TEL GS1 DELTA 0 0 Guide Star DEC Fixed parameters DET1 WIN1 UIT1 2 AFC UVB exposure time DET2 WIN1 UIT1 0 5 AFC VIS exposure time DET3 DIT 1 AFC NIR DIT DET3 NDIT 1 Number of AFC NIR DITs SEQ AFC CORRECT ET T AFC correct flag SEQ AFC MAXD 20 Maximum distance for AFC cross correlation SEQ AFC WSIZE 64 Window size for AFC cross correlation SEQ PRESET Ma T Preset flag INS MODE SLITSPEC IFUSPEC Instrument mode IFUSPEC ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Table 21 User defined and fixed parameters for XSHOOT Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 123 of 161 ER ifu acq rrm XSHOOTER_ifu_acq_rrm Keyword Range Default Value Label in P2
171. tive x it moves in and becomes particularly noticeable in the dichroic cut off region between UVB and VIS arms It is strongest in the last order of the UVB spectrum in the wavelength range of the dichroic reflectivity cut off see Figure 13 left In the VIS the ghost is noticeable in several orders and its intensity is lt 0 5 of the parent spectrum see Figure 13 right It is particularly relevant when observing a bright object with the nod on slit template Figure 13 ghost spectra in UVB and VIS produced by back reflection in the two dichroics A possible ghost seems also to exist in the NIR arm Figure 14 it lies at the bottom edge of some orders at 5 when the observed object is bright It counts for less than 1 Figure 14 Ghost spectrum in the NIR arm ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 REN Issue P97 O Date 19 08 2015 Page 58 of 161 2 4 5 Inter order background Inter order background subtraction is a difficult task in particular where order spacing is minimum in the red part of the VIS 4 unbinned pixels Therefore whenever a good inter order background subtraction by the pipeline is important we recommend not using the 2x2 binning mode 2 4 6 NIR frames with the K band blocking filter features e There is a leak in the K band blocking filters implying that one can see in the right top corner some light However this ligh
172. tmospheric dispersion compensators ADCs in the UVB and VIS arms and a warm optical box in the NIR arm e The three arms are fixed format cross dispersed chelle spectrographs that operate in parallel Each one has its own slit selection device o The UV Blue spectrograph covers the 300 550 nm wavelength range with a resolving power of 5100 for a 1 slit o The Visible spectrograph covers the range 550 1000 nm with a resolving power of 7500 0 9 slit o The near IR spectrograph this arm covers the range 1000 2500 nm with a resolving power of 5300 0 9 slit It is fully cryogenic 2 2 Description of the instrument sub systems This section describes the different sub systems of X shooter in the order they are encountered along the optical path going from the telescope to the detectors see Figure 2 The functionalities of the different sub units are explained and reference is made to their measured performance ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 ES Issue P97 Date 19 08 2015 Page 19 of 161 2 2 1 The Backbone Telescope Calibration unit Instrument shutter Calibration mirror slide 3 positions mirror UVB tip tilt mirror IFU VIS ADC UVB ADC VIS tip tilt mirror NIR Warm optical box Dichroic 1 Dichroic 2 Figure 3 3D view of a cut through the backbone 2 2 1 1 The Instrument Shutter and The calibration unit
173. tors Among them were observed very bright stars and 48 presets were performed in a single summer night 1 OB every 9mn the Moon 6 9 Frequently Asked Questions e The health of the instrument is monitored every day You may want to see the current Quality control plots at http www eso org observing dfo quality XSHOOTER reports HEALTH trend report BIAS U VB med master HC html e Is it possible to do pre imaging for astrometric and photometric purposes with the AG technical CCD OBSOLETE with the release of the imaging mode Not yet even if It was successfully used during VM runs for preparing the OBs for blind offsets or to investigate better the field However the imaging mode is not yet characterized and thus not yet offered to the community In addition the AG detector suffers from pick up noise About the WCS it is good but an offset of about 1 in DEC is still present We will improve the WCS in P88 e Is it possible to do the nodding in 1 arm only the NIR one for instance No it is not possible due to the current technological limitations e Can we skip the AFC It is possible to occasionally skip AFC in BOB for observations done near zenith with a wide slit and or under bad seeing However this is not a recommended action since it may make data extraction more difficult object no longer at the expected position along the slit and or lead to additional slit losses Moreover the AFC is used to take into account t
174. troms Atmospheric dispersion effect no ADCs on the position of the spectrum inside different orders depending on the airmass and the arm UVB top VIS middle NIR bottom The wavelength is in ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 28 of 161 As consequences in stare mode object centered in the slit if the observation is conducted at airmass 1 2 with the slit angle at parallactic angle then the drift between the blue and red order spectrum will be of 1 6 in the UVB arm 0 6 in the VIS arm and 0 2 in the NIR arm if the observation is conducted at airmass 1 6 with the slit angle at parallactic angle then the drift between the blue and red order spectrum will be of 3 5 in the UVB arm 0 8 in the VIS arm and 0 3 in the NIR arm Such kind of drifts is important to take into account in case of nodding observations to avoid too many flux losses even with the slit at the parallactic angle It is again more important if the slit angle is different than the parallactic angle b Comparison of ADCs efficiency at different slit angle The measure was performed at relatively high airmass AM 1 8 and compares the flux between the slit position parallactict90 degrees and parallactic angles ratio flux perpendicular flux parallactic The average value corresponds to the average of measurements for each order the
175. utomatically corrected in the UVB and VIS arms thanks to the two ADCs However they are fully working up to airmass 2 For larger airmass the compensation is not perfect and above airmass 2 5 bad In IFU mode however there is no correction for atmospheric dispersion the two ADCs come after the IFU in the light path and are set to their OFF position where they do not disperse light The user has to choose which wavelength will be kept fixed at the centre of the IFU during observations using the SEQ IFU WLGT parameter in the XSHOOTER ifu acq template It is set to the middle of the atmospheric dispersion range 470nm by default Users are therefore recommended to orient the IFU parallel to the parallactic angle whenever possible and should keep in mind that at high airmass the amplitude of the dispersion is larger than the 4 of the IFU field Therefore we always recommend to specify a low airmass for the observations better than 1 5 should be enough 3 4 1 3 Exposure time in the NIR arm Only a limited choice of DIT values is allowed for the NIR observations in service mode This has been decided only on an operational basis i e to avoid endless daytime calibrations In particular there are no constraints for short NIR exposure up to 300s while only the following selection is available in the case of longer exposure 2 300s DIT 300 480 600 900 and 1200 s Note that the DIT 1800s is no longer offered as it has been verified that it
176. w eso org observing dfo quality pipeline status html XSHOOTER More information on the current pipeline problems and limits is available at http www eso org observing dfo quality XSHOOTER pipeline pipe_problems html The cookbook reduction of the data reduction with the pipeline is currently ongoing and will be available as soon as possible at http www eso org sci facilities paranal instruments xshooter doc Note that a cookbook is already included in the pipeline manual and in the reflex tutorial If you use the X shooter pipeline to reduce the data please cite Modigliani et al 2010SPIE 7737E 56M ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P97 Date 19 08 2015 Page 114 of 161 6 8 Examples of observations with X shooter During this first year of operation some achievements were done For example galaxies at high redshift z 7 5 were observed highly extinguished stars Vmag 27 were observed GRB host galaxy of R gt 24 were observed as well as GRB afterglow of Rmag 23 5 the RRM was successfully activated and several z of GRBs obtained time series of variable objects more than 100 consecutive exposures were done the continuous scanning of open and globular clusters was done for obtaining their integrated light Some bright objects were also observed but with some difficulties because in normal weather conditions they saturate the detec
177. y when the science performed at night did it ag As requested As requested As requested On request Twilight spectroscopic skyflats Imaging mode see The corresponding section ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc Issue Date Page a Darks every day monitoring darks DITXNDITXxNEXP of 1sx3x3 5sx3x3 300sx1x3 600sx1x3 are taken The other darks are taken only if they are science triggered They are taken at daytime following the science observation as follows VLT MAN ESO 14650 4942 P97 19 08 2015 105 of 161 Science of standard Triggered calibrations DIT NDIT DIT NDIT N exposures lt 300s lt 2 DIT 1 3 lt 300s gt 3 DIT 3 1 300s lt lt 2 DIT 1 3 300s lt gt 3 DIT 3 1 In case the science frames use a combination DITXNDIT corresponding to the monitoring darks or to other science standard frames the darks are not duplicated There is not anymore a difference SM or VM b Now only the 1x1 binning is taken in the UVB VIS Other binning ORDERDEF are taken upon request c The RV standard star OBs are not ready we encourage the users to specify their own RV standard star by submitting corresponding OBs using the telluric star templates ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4

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