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X-shooter User Manual

1. U B V R oe oo aoa 24 94 27 27 27 20 27 13 26 73 11 i en 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 P95 Date 20 11 2014 Page 88 of 158 eStability 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 1 5 RON Ie RON lo 2 4 w E a 0 5 a s G a u 9 gt a ee mte e a BE a A m 2 0 fo a s sf int 5 amp s 2 j a u A Ml
2. cccccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeneeeeeeees Spectro photometric Standard Stars ccccccccccccccccesssesecccceeeeeeeseeseeceeeeseeeaaeaeases Telluric standards cccccccceeeceeceeeccceeeaecseeeeeeeeceeaaeaaaaeceeeeeeeeaaeaaeeeeeeeeesaaaenseeeeesess Attached night calibrations must be taken after a science template Arcs multi pinhole 2d wave maps wavelength calibration 24 TAL Sli Daytime Calibration templates ccccceeeeeeeeeeeeeeeeeeneeeeeeeeeeeeeeeeneeeeeeees t and IFU arc lamp calibrations resolution tilt 0 0 0 0 eee eeeeeeeeeeeeeeeeeeeetteeeeeeeees Flatfield pixel response orders localization cccccccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeees Format check 1 guess of wavelength solution eeenene Order definition 1 guess of order localization cc cccecceccccessesseseesessescessenenseatens Arcs multi pinhole 2d wave maps wavelength calibration 42420 Detector Calibrations ccccccccsseeeeeeeeeeeeeeeeaeeaaaeeeeeeeeeeaaeaaeeeeseeeesaaaeasaeeeeeesenaaaga 7 1 8 7 2 7 2 1 1 2 2 7 2 3 Imaging mode templates MANUAL icc cccccccccsccsccccceesccenecessceneceseceneceeecenenenncees 5 IS Re ee es Sareea eh ee ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 11 of
3. 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 Number 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
4. 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 Fixed Value ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 14
5. XSHOOTER_sit_acq 1 __XSHOOTER sit_obs_AutoNodOnslit Instrument A amp G Filter TCCD Exposure time Get Guide Star from CATALOGUE RA of guide star 0 DEC of guide star 0 offset RA 35 6 Offset DEC 20 5 B Specify here in the blind offsets from the reference acquisition star to 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 UVB Slit VIS Slit NIR Slit UVB Exposure time UVB readout mode VIS Exposure time VIS readout mode NIR Exposure time DIT no of NIR sub integrations NDIT Number of exposures for UVB det NE Number of exposures for VIS det NEXP Number of exposures for NIR det NINT Nod throw length arcsec Width of the jitter box arcsec Number of cycles Go to zero offset position at the end 1 0x11 0 9x11 0 9x11 5 100k 1pt hg 10 100k 1pt hg 15 1 HJTrourrr ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany ES Q Doc Issue Date Page VLT MAN ESO 14650 4942 P95 20 11 2014 73 of 158 la o A Obs Description Target Constraint Set Time Intervals demonstration rTarget Name acquisition_star_blind_offset Right Ascension 10 00 00 000 Declination 12 12
6. cccccccccccccccceeeeeeeeceeeeeeeeeeeeeeeeeeees 111 6 9 Frequently Asked Questions 0 cece ee eeeeceeeeeeeeeeteeeeeeeeeeeeeeeeeeeenaeeeeeeeeereeeeenaaaes 111 Refstencematenal ciatetsrntslettteimaeiteniuetieieprshe het obeenstoniue E 113 7 1 Templates reference sn 113 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 10 of 158 Orientation ANd CONVENTIONS 0 ieee eeceecceeeceeeceeeceeeceeecaeeceeeceeeceeceeseeeeeeens 7 1 1 7 1 2 Examples of position angles and offsets cccccccccccccccceceeeeeeeeeeeeeeeeeeeeees 7 1 3 Sli Acquisition templates ccccccccceeeeeceeeeeeeeeaaeeeeeeeeeeeeeeaaaeaeeeeeeeeeeeeaaeaneees t acquisition templates 4u44sannnsnnnnnnnnennnnnnnnennnnnnnennnnnnnnnnnnnnnssnnnrennn IFU acquisition templates cccccccccscceeeeeeeeeeeceaaeeceeeeeeeeeeesaaaeaaaeeeeeeeeeeeaaegneeeeeeeees 7 1 4 Flexure compensation templates that can be used in OBs 7 1 5 Science templates 0 c ssesssssesssssssssssssssssssssseeessssssssessesssssseeseeseeeeees Sli t observations o oo cece eeccecceccecceceuecueeceeceeceeceeeeceueeaeeneeaeeceeeeeeeeaeeaseneeaueneeseeeeeeneeaes IFU ODSErvattiONS cececcceccecceccneceeeceeceeceeeeeceseaeeeseneeaeeceeeueeeeeaesaeeneeaeeneeseeteeeneeaeenes 7 1 6 Night time Calibration Templates
7. cccccccccccccccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeneeeeeeeeeeeeeseeeessesesenenenass 59 2 4 8 2 Spectrograph flexures ccccccccccccccccccececeecceeeeeceeeceeeeeeeeeeeseeeeeeeseeeeeeeeeseseness 59 2 4 9 Radial velocity aACCUTaCy PRRNRPRERRERRERFEHEHEENEERERELKEREERECHEFEFRELHEREERECHLERERELKEEFERELHERERREEFE 59 2 4 10 NIR 11 order vignetting K band c ccccccccccssescsssesescscecesesessceseeeetseeseateees 60 2 4 11 VIS CCD pick up noise ususssssnsenesensnsnenensnnnnnnnnnnnenan anna anna anne anne 61 2 4 12 NIR IFU parasitic reflections 44440440440000R0RRnnnnnnnnnnnnnnnnnnnnnnnnnn 61 2 4 13 UVB VIS ADCS problem cccccccccccccccccceececeeeeeeeeeeeeeeeeeseeeeeeeseseeeeesesesenenenass 62 2 4 14 Drift of acquisition reference positions cccccccccccceeeeceeeeeeeeeeeeeeeeeeeeeeeeeess 62 24 15 TOCD features icicccciscccccciecerscsicccescstencetcstcnosetetentescesibesesstenbesseistesstatenteasecsness 62 2 Observing with X shooter suisccacencsastcascanadoeu nee er 63 3 1 Observing modes and basic ChOiCES cccceceeeeeeeeeeeeeeeeeeeeeeeeenenaeaeeeeeeeneeees 63 3 2 Marget acquisito rs iec Ee a Eee 64 3 2 1 Acquisition 00P ue ee nenn 64 3 2 2 Blind offset precisions nnnnnnnnnnnnnnnnnnnnnnnnnnn nn 65 3 3 Examples of OBs preparations acquisitions With P2pp3 uuu04440 0 nnnnennnnnnnen 66 3 3 1 Direct aequisitionsansiieasenn eier 66 3 3 2 Blind offsel ACU MIS
8. 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 the spectrograph flexures with respect to the WAVE calibration at daytime ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 112 of 158 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 s
9. 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 M nchen Germany 91 92 P92 P93 Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 6o0f 158 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 acknowledgements warning abou
10. European Organisation Organisation Europ enne Europaische 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 P95 Date 20 11 2014 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 Christophe Dumas Name Date Signature ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 2 of 158 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 30f158 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 Limited Integration
11. slit 323x5683 SCI CAL ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany
12. 4 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 rectangles 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 b
13. 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 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 XSHOOT Doc Issue Date Page sequence of offsets and object or sky observations VLT MAN ESO 14650 4942 P95 20 11 2014 125 of 158 ER slt_obs GenericOffset lt allows to decide the 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 ex
14. 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 Angstroms 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 P95 Date 20 11 2014 Page 28 of 158 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 perfor
15. band flatfield ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 96o0f 158 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 Q 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 IE WG martayan nboi 5045 dutie hooterfmoveuT2to IRAF Image Reduction and Analysis Facility PACKAGE immatch TASK imcombine input Na listebias List of images to combine output masterbias fits List of output images headers gt List of header files optional bpmasks gt List of bad pixel masks optional rejmask gt List of rejection masks optional nrejmas 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 IMCHB keywords logfile STDOUT Log file combine median Type of combin
16. for combining the images 3 Create the masterflatfield eSame 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 without 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
17. 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 P95 Date 20 11 2014 Page 158 of 158 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 x11 slit 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
18. 158 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 IFU 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 P95 Date 20 11 2014 Page 12 of 158 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
19. 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 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 E 50 40 u oO of light entering sl ho oO 0 l 1 1 1 1 3000 3500 4000 4500 5000 5500 Wavelength A 40 T T T T T of light entering slit 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 P95 Date 20 11 2014 Page 300f
20. 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 Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 154 of 158 Science STARE imaging observation XS
21. 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 Range 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 s
22. 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 from 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 t
23. 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 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 P95 Date 20 11 2014 Page 36o0f 158 2 2 4 2 Optical layout Entrance slit ae 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 mirr
24. 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 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 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 trackin 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 P95 20 11 2014 27 of 158 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 IS fi
25. 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 M nchen Germany Doc Issue Date Page 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 P95 20 11 2014 52 of 158 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 P95 Date 20 11 2014 Page 53 of 158 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
26. 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 P95 Date 20 11 2014 Page 76of 158 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 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
27. 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 P95 Date 20 11 2014 Page 40f158 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 14 2 2 4 2 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 tables 1 9 12 13 16
28. 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 which corresponds to an accuracy of 7 5 km s at 800 nm 0 004 nm in the NIR arm whi
29. 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 P95 Date 20 11 2014 Page 98 of 158 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 Instrument setup at the end of acquisition SLIT see b q IFU see b Observations 1x1 slow fast 68s 16s UVB 1x2 slow fast 34s 8s 2x2 slow fast 17s 4s Detector readout 1x1 slow fast 89s 215 See also 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 depend
30. 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 summarized 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 Redu
31. is no plot yet available ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany ES Q Issue P95 QO Date 20 11 2014 Page 91 of 158 eDistortion 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 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 P95 Date 20 11 2014 Page 92 of 158 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 s
32. necessary this process is re iterated 5 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 6 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 7 The telescope is offset to the reference pixel on the detector corresponding to the position of the image the 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 8 Loop over steps 5 and 6 9 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 10 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
33. 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 Issue P95 Date 20 11 2014 Page 71 of 158 Doc VLT MAN ESO 14650 4942 Time Intervals 08 30 08 45 09 00 09 15 0930 09 45 10 00 10 15 10 30 10 45 11 00 11 15 11 30 11 45 12 00 12 15 se demonstration Yow Obs Description Target Constraint Set Time Intervals Time Intervals Sid Time Intervals Sidereal time 12 30 12 45 NewTI ffi 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 3 3 2 Blind offset acquisition AA Ale o Obs Description Target Constraint Set Time Intervals Doc Issue P95 Date 20 11 2014 Page 720f158 demonstration VLT MAN ESO 14650 4942 kK x Obs Description OD Name User Comments IND OFFSET ACQUISITION Instrument Comments Execution Time Recalculate TemplateType acquisition Template XSHOOTER_sIt_acq XSHOOTER_ifu_acq_rrm XSHOOTER_sIt_acq_rrm XSHOOTER_ifu_acq Add Duplicate Delete
34. 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 Instrument 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 P95 Date 20 11 2014 Page 138 of 158
35. 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 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 P95 Date 20 11 2014 Page 31 of 158 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 P95 Date 20 11 2014 Page 32o0f 158
36. 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 For 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 Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 40 of 158
37. template XSHOOT Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 139 of 158 ER ifu cal UVBVisArcAtt XSHOOTER_ifu_cal_U VBVisArcsAtt 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 ER ifu cal VISLampFlatAtt XSHOOTER ifu_cal_VI SLampFlatAtt Keyword Range Default Value Label in P2PP Free Parameters DET2 WIN1 UIT1 0 36000 VIS exposure time DE
38. 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 Schwarzschild 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 P95 20 11 2014 35 of 158 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
39. 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 use 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 im
40. 0 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 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 P95 Date 20 11 2014 Page 45 of 158 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 differen
41. 0 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 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 Doc Issue Date Page VLT MAN ESO 14650 4942 P95 20 11 2014 124 of 158 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
42. 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 org sci facilities paranal instruments xshooter news html It is not yet decided whether 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 o
43. 000 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 AGSNAPSHOT ME F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Table 24 Parameters for the template XSHOOT Doc Issue Date Page VLT MAN ESO 14650 4942 P95 20 11 2014 123 of 158 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 10
44. 11 2014 Page 131 of 158 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 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 P95 Date 20 11 2014 Page 132 of 158 template is
45. 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 P95 Date 20 11 2014 Page 74 of 158 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 automatically 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 corr
46. 14 the snapshots saved during the acquisition process are of sub optimal quality It is worth to note that the acquisition itself and the imaging mode are not affected at all by this problem ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 63 of 158 3 Observing with X shooter 3 1 Observing modes and basic choices In P93 X shooter offers three observing modes SLIT spectroscopy IFU spectroscopy 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 sta
47. 14 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 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 P95 Date 20 11 2014 Page 51 of 158 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 ord
48. 158 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 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 If 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
49. 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 rsranss sn with filter 1238nm 20 without filter 1238nM sescccesceee with filter 1300nm without filter 1300nm with filter 1682nm without filler 1682nm snersennun n b gi 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 P95 Date 20 11 2014 Page 47 of 158 2 2 6 4 Optical layout 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
50. 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 P95 Date 20 11 2014 Page 136 of 158 Table 38 User defined and fixed parameters for SHOOT ifu cal TelluricStdStare The template is identical to XSHOOTER ifu obs Stare XSHOOTER_ifu_cal_Tell uricStdStare Keyword Range Default Value Label in P2PP Free paramete rs 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 Dete
51. 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 spherical 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 s
52. 2 READ CLKDESCR see Table 6 400k 1pt lg VIS readout mode SEQ NEXPO UVB 0 100 UVB No of exposure SEQ NEXPO VIS 0 100 VIS No of exposure Fixed Value INS MODE SLITSPEC IFUSPEC SLITSPEC Instrument Mode INS OPTI3 NAME see Table 5 Pin_row UVB Slit slide INS OPTI4 NAME 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 P95 Date 20 11 2014 Page 141 of 158 Table 50 User and fixed keywords for XSHOOTER slt cal NIRArcsMultiplePinhole XSHOOTER slt_cal_NIRArcsMultiplePinhole Keyword Default Value Label in P2PP DET3 DIT 0 36000 NIR exposure time Number of DITs DET3 NDIT 10 SEQ NEXPO NIR No of exposures Fixed Value INS MODE SLITSPEC Instrument Mode INS OPTI5 NAME NIR Slit wheel ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 142 of 158 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 _slit_cal_UVBVisArcs 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 DET1 WIN1 UIT1 0 36000 30 UVB exposure time DET1 READ CLKDESCR see Table 5 400 1pt lg U
53. 20 2 CALIB 100k Ipthg Ix2 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 7 0 100 7 0 500 1 0 500 1 Range Dail 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 P95 Date 20 11 2014 Page 150 of 158 Table 70 Template for taking detector FF and biases for the linearity measurements of the detectors XSHOOTER gen_cal_CCDFlat tsf To be specified DET1 READ CLKDESCR DET1 WIN1 UIT1 DET2 READ CLKDESCR DET2 WIN1 UIT1 SEQ NEXPO UVB SEQ NEXPO VIS Fixed values Parameter 100k 1pt hg 100k 1pt hg 1x2 100k 1pt hg 2x 400k 1pt lg 400k Ipt lg 1x2 400k Ipt lg 2x 100k Ipt hg 0 36000 1 100k 1pt hg 100k 1pt hg 1x2 100k 1pt hg 2x2 400k Ipt lg 400k Ipt lg Ix2 400k Ipt Ig 2x 100k Ipt hg 0 36000 1 0 500 1 0 500 1 Range Default UVB readout mode UVB Exposure time VIS readout mode VIS Exposure time Number of exposures for UVB det NEXP Number of expos
54. 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 magnitude 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 P95 Date 20 11 2014 Page 55 of 158 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 a
55. 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 exposures then the execution time will be dominated by the UVB VIS couple 5x137 685s gt 601s NIR time c p2pp check 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 P95 Date 20 11 2014 Page 101 of 158 6 Calibrating and reducing X shooter data 6 1 X shooter calibration plan The calibration plan has been revised during P86 P8
56. 3 Thelfle cesesne en 21 2 2 1 4 The Acquisition and Guiding Camera 444444444ssnnnnennnnnn nennen 23 2 2 1 5 The dichroic box 4444sssnnnennnnnnnnnnnnnnnnnnnnnnnnnennnnnnnnnnnnnnnensnnnnrenn 24 2 2 1 6 The flexure compensation tip tilt mirrors ceeeeeeeeeeeeeeeeeeeeeseeeeeeeeees 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 PERRERRRERRERRPEREHRERERREEREPERSERREREREE RRERERRERRERERSEERHRERRERREEERSEERSFERSERR 35 2 2 4 The UVB Spectrograph cccccccccceceeeeeeeeeeeeeeeaaeeaceeeeeeeeeeeaaeaaaeeeeeeeeeesaaeneees 35 2 2 4 1 Slit carriage SERROSPBRUERPRERPEHREEEREGERFREPEREREEFRECERBEEFEUERLECERCEFEEERITFHEEFPECERPEEPEUEREESPRCEREEEREERE 35 2 2 4 2 Optical layout een ernennen 36 2243 Deteclor wre se Ceactertanssiashacaahacones stu E e aee e a EE 37 2 2 5 The WIS Spectogaph a a I Ea EEA EEEE E 39 2291 SL GAL MAGE nennen 39 2 2 5 2 Optical layout BIBERBORREREIEREREER EEOERESFELBEREEFPFCUFEBRFERENDERFEOHFESCEIERDEETEGEREEEFEERHERE PFEREERCEEERE 39 2 2 5 3 Detector usssssesssennnnsnnnnnnennnnnnnnnnnnnnnnnnnnnnnennnnnnnnnnnnnnnnnssnnnrernnnnnne sn 39 2 2 6 The NIR spectrograph 444444ssnnnsnnnnnnnnnennnnnennnnnnnnnennnnnnnennnnnnnne san 40 2 2 6 1 Pre slit optics and entrance window usssssnnsss
57. 4 Page 19 of 158 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 PANS Dichroic 2 Figure 3 3D view of a cut through the backbone 2 2 1 1 The Instrument Shutter and The calibration unit 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 awavelength 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
58. 400k_1x2 T AA monthly detector monitoring Set of detector T LINEARITY_VIS_100k_1x2 FF biases monthly detector monitoring Set of detector oe LINEARITY_VIS_400k_1x2 FE biases monthly detector monitoring Set of detector sa LINEARITY _UVB_100k_2x2 FF biases monthly detector monitoring Set of detector FEA LINEARITY_UVB_400k_2x2 FF biases monthly detector monitoring Set of detector P LINEARITY_VIS_100k_2x2 FF biases monthly detector monitoring Set of detector a LINEARITY_VIS_400k_2x2 FF biases monthly detector monitoring Set of LINEARITY_NIR detector monthly detector monitoring FF Imaging mode A dedicated document will provide all the details 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 P95 Date 20 11 2014 Page 104 of 158 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 calibr
59. 7 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 Hee andeneck COD biag 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 e a 5 setting 5 ON OFF daily oe when triggered 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 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 f 1 ON OFF Every 3 days inholes and slits spectral Th Ar or 1 setting 1 setting setting i SM i ae P Ar Xe Hg Kr ARC Flat multi pinhole 1 1 1ON OFF Onrequest Mult order definition taken on request IFU slitlet 2 2 2 6 monthly Pipeline calibration cube distances TBC reconstruction on i 2 2 2 On req
60. 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 P95 Date 20 11 2014 Page 5 of 158 Modified sections 2 2 1 4 2 2 4 5 2 4 3 3 4 3 4 1 2
61. 9 of 158 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 Value 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 slt_cal_MultipleOrderDef tsf To be specified 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 OPTB NAME INS OPTI4 NAME INS OPTB NAME MODE 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 lg 1x2 400k Ipt ig 0 36000 60 0 36000 20 1
62. C 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 P95 Date 20 11 2014 Page 127 of 158 fixed parameters for the template XSHOOTER ifu obs FixedSkyOffset It allows to alternate object and sky observations taking the sky at fixed po
63. C 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 gt 24 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 Readou spaad List of filters Angles and binning STARE Fast readout UBVRI Soeur patalacie angle IMAGING GENERIC binning 1x ugriz or defined angle on OFFSET g eee 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 giv
64. Date 20 11 2014 Page 120 of 158 ER ifu acq rrm XSHOOTER_ifu_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 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
65. 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 Page 1 5 Reference Documents SIRON VLT MAN ESO 14650 4942 P95 20 11 2014 14 of 158 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 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc Issue Date Page 1 6 Acknowledgements Please if you use XSHOOTER data cite the f
66. 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 integrations 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
67. HOOTER_mg_obs tsf To be specified Parameter T Hidden Range Default Label SCS DET4S WINL UITI no 0 36000 7 TCCD Exposure time DPR CATG no SCIENCE Data Prod Cath DPR TECH no IMAGE Data Prod Tech DPR TYPE no OBJECT Data Prod Type INS FILTL NAME no u_prime g_prime r_prime i_prime z_prime UB V R I V G Filter SEQ NEXPO no 0 1000 7 Number of exposures arameter H n Value La Science Generic OFFSET imaging observation XSHOOTER_ mg_obs_GenericOffset tsf To be specified Hidden Range Date DET4 WINLUITI 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 U B V R I V G Filter SEQ NEXPO no 0 100 7 Number of exposures SEQ NOFFSET no 1 1002 Number of offsets SEQ OBS TYPE no OS List of TYPE offsets e g OSSO SEQ OFFSET COORDS no SKY DETECTOR SKY Osi 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 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc Issue Date Page VLT MAN ESO 14650 4942 P95 20 11 2014 155 of 158 Calibration template for observation of standard field for distortion map same functionality as the science imagi
68. Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Table 56 User and fixed keywords for XSHOOT Doc Issue Date Page VLT MAN ESO 14650 4942 P95 20 11 2014 145 of 158 ER 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 XSHOOT ER 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 P95 Date 20 11 2014 Page 146 of 158 Format check 1 guess of wavelength solution Table 58 User and fixed keywords for XSHOOT ER slt cal UVBVisArcsSinglePinhole XSHOOTER_slit_cal_UVBVisArcsSinglePinhole Free
69. LT1 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 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 Fil 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 TE 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 P95 Date 20 11 2014 Page 118 of 158 ER slt acq rmm XSHOOTER_sit_acq_rrm Keyword Range Default Value Label in P2PP Free parameters SEQ RRM REGISTER Tak 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 different
70. OM a nn nn 72 3 4 Spectroscopic observations unnnssssssnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn 74 3 4 1 Overview and important remarks 44nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nn 74 3 4 1 1 Observing modes u 444444444400nnnnnnnnnnnnnnnnnnnnnannnnnnnnnnnannnnnnnnnnnnnnnnnnnnnn 74 3 4 1 2 Effect of atmospheric dispersion uussssssssssssnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn 74 3 4 1 3 Exposure time in the NIR arm 242222444004sssannnnnnnnnnnnnennnnnnnnnnnnnn nn 74 3 4 2 Staring SLIT and IFU ne elle 75 3 4 3 Staring synchronized SLIT and IFU uuuuussssssnnnnnnnennnnsnnnnnnnnnnnnnnnnnnn 75 3 4 4 Nodding along the slit SLIT only suuu442424444nnnnennnnnnnnnnnnnnnnnnnnnnnnn 76 3 4 5 Fixed offset to sky SLIT and IFU 222222440snnnennnnssnnnnnnnnnnnnnnnnnnnnnnnnnn 77 3 4 6 Generic offset SLIT and IFU u en 77 3 5 Observation strategy summary and tricks 2244444snnnnnnnnnnnnnnnnnnnnnnnnnnn ern 78 3 5 1 Instrument setup 2424400000ssnnnnnnnnnnnnnnennnnnnnnnnnnnnnnnnnnnnennnnnnnnnessnsnnrnnnn 78 3 5 2 Observation strategy 244444404n44nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn 79 3 5 3 Telluric standard stars and telluric lines correction see also Sect 6 6 1 81 3 5 4 Observing bright objects limiting magnitudes and the diaphragm mode 81 3 5 5 Rea
71. PEC 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 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 144 of 158 Table 53 User and fixed keywords for XSHOOTER slt cal VISLampFlat
72. SET ZERO no TF T Go tzero 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 DAYTIME IMAGING TEMPLATES Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 156 of 158 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 WINI1 UITI 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 Number of exposures Fixed values Parameter Hidden Value Label Calibration template for twilight flatfields 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 1dden alue La Calibration template to measure the detector gain and linearity XSHOOTER_img_cal_DetLin tsf To be speci
73. SO 14650 4942 Issue P95 Date 20 11 2014 Page 8 of 158 TABLE OF CONTENTS 1 Tal cele 0 e 0 se eee 11 1 1 SCOPE apa PRIUINBE ENTE BEE NERUNL LEE EN CELHERDEERDIEONLEIUEENELEREFEELLELUEENEURHFERLLELHEUNEEERNFERELELUERNLERENFENER 12 1 2 X shooter in a nutshell usss0ssssnnnnennnnnnnnnnnnnnnennnnnnnnnnnnnnnennnnnnernnnnnnnn 12 1 3 Shortcuts to most relevant facts for proposal preparation cccccceeeeeeeeeeeeeeeees 12 1 4 List of Abbreviations amp Acronyms 44444ssnennnnsnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn nn 13 1 5 Reference Documents ccccccccccccceceeeeceeeececceeceeeeeceeececeeceeeeceeceeeeeeeeeeesseseeeeess 14 1 6 Fate inlei v 6 01 40 10 1 SPRAEHEREERPENREEFEHCHERELETEHHEEFEEUUEREELFEHHEEEPRCHEREERTEHHEEFEIUUEREELFEHREEFERCHERLELFENE 15 1 7 CONAC a fact aidan A A 15 1 8 NOS a E e enter een 16 Technical description of the iNStrUMENt cccccccccccccccecceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeness 17 2 1 Overview of the opto mechanical design 44444sssnnnnnnnnnnnnnnnnnnnnnnnnnnnnn 18 2 2 Description of the instrument SUD SYStEMS cece cceeeteeee eter eee eeeetteeeeeeeeeteeees 18 2 2 1 The Backbone ssssssssssnnnnnennnnnnnennnnnnnnennnnnnennnnnnnnesnnnnnennnnnnnee sn 19 2 2 1 1 The Instrument Shutter and The calibration unit n 19 2 2 1 2 The Acquisition and Guiding side z 2 028 22 0 20 221
74. Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 20of 158 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 a flat 45 mirror with 3 positions 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 P95 Date 20 11 2014 Page 21 of 158 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
75. 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 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 121 of 158 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 anymore because during the acquisition everytime an offset is performed a snapshot of the A amp G camera is saved Table 22 Parameters for stare mode observations with the template XSHOOTER slt obs Stare XSHOOTER_slt_obs_Stare Keyword Range Default Val
76. T2 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 P95 Date 20 11 2014 Page 140 of 158 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 XSHOOTER slt_cal_UVBVisArcsMultiplePinhole Free Parameters Keyword Range Default Value Label in P2PP DETI WIN1 UIT1 0 36000 UVB exposure time DET1 READ CLKDESCR see Table 6 400k 1pt lg UVB readout mode DET2 WIN1 UIT1 0 36000 VIS exposure time DET
77. Table 31 User and fixed keywords for XSHOOT Doc Issue Date Page VLT MAN ESO 14650 4942 P95 20 11 2014 129 of 158 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 T F F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Table 32 User defined and fixed parameters for XSHOOT Doc Issue Date Page ER slt_cal_ SpecphotStdOffset VLT MAN ESO 14650 4942 P95 20 11 2014 130 of 158 The template is identical to that for alternate
78. VB 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 P95 Date 20 11 2014 Page 143 of 158 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 see 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 IFUS
79. 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 yet 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 P95 Date 20 11 2014 Page 33 0f 158 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 b
80. aging 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 P95 Date 20 11 2014 Page 24 of 158 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 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
81. ally 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 P95 Date 20 11 2014 Page 75 of 158 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 XSHOOTER 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
82. also after ThAr calibrations arcs 2D maps or format checks For 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 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 P95 Date 20 11 2014 Page 56o0f 158 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 positive x it moves in and becomes particularly noticeable in the dichroic cut off regi
83. any Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 100 of 158 The acquisition and setup overheads XSHOOTER_sit_acg setup 409 30 439s acquisition integration times of 1s 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 deadtime 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 readout 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
84. arameters 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 P95 Date 20 11 2014 Page 134 of 158 Table 36 User and fixed keywords for XSHOOTER_slt_cal_Tellurics identical to the XSHOOTER slt obs Stare one tdStare The template is XSHOOTER _slit_cal_TelluricStdStare Keyword Range Defa
85. arget 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 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 P95
86. ass 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 telluric 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 P95 Date 20 11 2014 Page 108 of 158 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 t
87. ate 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 is XSHOOTER slt_cal UvbVisArcsMultiplePinhole and XSHOOTER slt cal NIRArcsMultiplePinhole _ bosam e RE 77 ren amp ome pus 66200 amp 2 ase eher gt RR amp ece ond a Pe PT a oe sae o gt na sa s Bee ome lenan bannen a _ sa parma gt bene e u bss iy ea gt s ectee e gt ewe u eee bd be ran eee ewe 4 e Pp n 8 a s gt oh im pes eet er ni er na 6 s 4 Eve erg er gt b 2 nen bd 5 ne Pe bd e j Pr s a eee sw s r e ab posi ee8 e e s e m P _ ee e amp Pre PER eo amp sso s 2 pa 6 ou gt gt s gt ee gt gt gt o oe e pe e 2 e e we s s a a e e d e e
88. bsolute 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 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 p n 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 ob
89. ch 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 e Extended 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 templa
90. ch 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 P95 20 11 2014 60 of 158 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 P95 Date 20 11 2014 Page 61 of 158 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 also very low level pattern with a deviation from the background level of 1 Figur
91. cialis 1 jitter box 8 A oo Nod throw 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 P95 Date 20 11 2014 Page 77 of 158 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 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 posito
92. 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 target as well as the science target must be clearly indicated on the finding chart The accuracy of the blind offset is better than 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 P95 Date 20 11 2014 Page 66o0f 158 3 3 Examples of OBs preparations acquisitions with p2pp3 Note that in SM our USD colleagues will help you in case o
93. ct acquisition coordinates RA DEC equinox epoch proper motions in RA and DEC in arcsec year differential velocities in RA and DEC in s if any moving targets ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 69 of 158 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 P95 Date 20 11 2014 Page 70 of 158 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 ONewri ffi Edit X Delete click New TI to add a new Time Interval click on a Time Interval to select it If
94. ction 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 63 Observing strategy and sky subtraction see Section 3 3 on page 66 Overhead computation see Section 4 on page 83 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany 1 4 List of Abbreviations amp Acronyms Doc Issue Date Page VLT MAN ESO 14650 4942 P95 20 11 2014 13 of 158 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
95. ctor 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 P95 Date 20 11 2014 Page 137 of 158 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 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 exposure per offset position SEQ NEXP NIR 0 100 1 NIR
96. d aa tes ee SO 0 5 m ae Ll m 5D e o a A 2 e tr 1 cc gt e 2 1 5 A 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 20 photometric transparency seeing lt 1 3 no early twilight xe 1 5 z P 1 0 7 Ca A 0 5 ee eee eee eae aa eee aes ass ess aS os See SS S 0 0 5 H a r u g Eaa E E ee S Gs r h 1 0 56000 56100 56200 56300 56400 56500 56600 MJD ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc Issue P95 Date 20 11 2014 Page 89 of 158 eCalibration plan and observing strategies a Imaging mode acquisition and exposure times VLT MAN ESO 14650 4942 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 ET
97. der 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 P95 Date 20 11 2014 Page 58 of 158 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 P95 Date 20 11 2014 Page 59 of 158 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 readout speed and a voltage parameter have been set to minimize their effects without
98. dition 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 speed 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 P95 Date 20 11 2014 Page 109 of 158 6 6 2 Absolute flux calibration Spectrophotometric standard stars can be used to obtain the absolute efficiency of the instrument and derive an a
99. dout times in the UVB and VIS arms minimization of overheads 82 The XSHOOTER imaging modern en 83 Instrument and telescope Overheads ccceeeecceaeeeeeeeeeeeeeeeeaaeeaeeeeeeeeeeeaaeneeeeeeeees 98 5 1 1 Summary of telescope and instrument overheads nn nen 98 5 1 2 Execution time computation and how to minimize the overheads 99 Calibrating and reducing X shooter data cccceeeeeeeeeeeeeeeeeeeeeeeeeeeteeeeneeeeeeeeeeeeee 101 6 1 X shooter Calibration Plan 2 0 0 cceeeeeececeeeceeeecaeeeeeeeeeeeeeeeeaaeaeeeeeeeeeeeeaaaneteeeeeees 101 6 2 Wavelength and spatial scale calibration n 104 6 3 Flat field and Wavelength calibrations cccccccceceeeeeeeeeeeeeeeeeeneeeeeeeeeeeeeeeaaees 105 6 4 Spectroscopic Skyflats cccccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeseeeeeeeeeeeeeeeseeeeeeeeeeeeeeees 106 6 5 Attached Calibrations ccccccceeeeeceeeeeeeeeaeeeceeeeeeeeeeeaaaeaaeeeeeeeeeeaaaaaaaeeeeeeeeeeaaas 107 6 6 Spectrophotometric calibration 2222244444444nRnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnen 107 6 6 1 Telluric absorption correction 2222244444444Hsannnnnnnnnnnnennnnnnennnnnnnee nn 107 6 6 2 Absolute flux calibration ana a 109 6 7 The X shooter pipeline ssnnsssssnnnnnnennnnnnnnnnnnnnnnennnnnnnnnnnnnnnennnnnnrenn 110 6 8 Examples of observations with X SHOOtEl
100. e 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 this 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 P95 Date 20 11 2014 Page 17 of 158 VLT MAN ESO 14650 4942 2 Technical description of the instrument Th Ar D lamps NT Ar KrNeXe lamps FF lamps gt A amp G filter wheel Calibration unit A amp G H camera exposure VIS slit shutter EIVI instrument shutter 4 LN calibration mirrors 7 Sf H 7 acq pin mon 3 positions mirror 50 50 pellicle IFU 4 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 P95 Date 20 11 2014 Page 18 of 158 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 componen
101. e operation reject minmax Type of rejection project no Project highest dimension of input images Couttype real Output image pixel datatype Coutlimi 2 Gutput Limits Lxi x2 ul ge 7 23 Coffsets none Input image offsets masktyp none Mask type maskval 0 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 C1thresh INDEF Lower threshold Chthresh INDEF Upper threshold Cnlow 1 minmax Number of low pixels to reject nhigh 1 minmaxt Number of high pixels to reject inkeep 1 Minimum to keep Tpos or maximum to reject neg mclip yes Use median in sigma clipping algorithms lsigma 3 Lower sigma clipping factor Chsigma 3 Upper sigma clipping factor rdnoise 0 cedclip CCD readout noise electrons gain 1 cedelip CCD gain Celectrons DIN snoise 0 cedcelip Sensitivity noise fraction sigscal 0 1 Tolerance for sigma clipping scaling corrections pclip 0 5 pclip Percentile clipping parameter grow 0 Radius pixels for neighbor rejection mode ql gt Hie for HELP ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 97 of 158 2 Optionally create the masterdark eSame than 1
102. e template XSHOOTER ifu_obs GenericOffset It allows any sequence of offsets and object or sky observations 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 LF F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany 7 1 6 Night time Calibration Templates Spectro photometric Standard Stars
103. ection 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 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 intern
104. ee 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 P95 Date 20 11 2014 Page 147 of 158 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 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 waveleng
105. ei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 49 of 158 UVB arm miw oo MH Mat i piia 27 2 Do A FEB VAn Ye PT IRRE UT DaB A TIL a 07 IL UE DIE MIT ENEAN IL TE WAN Blue orders Blu VIS arm i Sa Red o EEN Red orders s a MW 1 1110 ep Ili P yin er ee LE E mime z Tat A E ET Er Blue ui pi at pik A Oy T lag me 2e picik iP sip Vi Red nid Wl NIR arm Lo ie gid TENN peti gh Lady ABET N U o E A URH aeee ee ie ALLE Aaa rine yy hg man ran LET pr I nat TEE Pay tell Winn l 1 ES I 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 Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 50of 158 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 5
106. eir 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 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 t
107. en 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 P95 Date 20 11 2014 Page 90 of 158 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_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
108. er 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 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
109. es 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 P95 Date 20 11 2014 Page 62 of 158 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 efficiency of XSHOOTER with disabled ADCs 2 4 14 Drift of acquisition reference pos
110. f 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 ee we 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 IXSHOOTER_sIt_acq_rrm Add XSHOOTER_ifu_acq_rrm J 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 Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 67 of 158 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 TemplateType science E added here nodding Template XSHOOTER sit_obs_Stare J XSHOOTER_sIt_obs_FixedSk
111. fied Parameter Hidden Range Default Label DET4 WINI1 UIT1 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 RI PV B PV V V G Filter SEQ EXPO STEP no 0 3600 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 P95 Date 20 11 2014 Page 157 of 158 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 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
112. fortunately 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 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 Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 26o0f 158 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 recently 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
113. he 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 According to the ETC and measurements one must not try to observe stars brighter than magnitude 3 because it will lead to saturate the detectors ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 82of 158 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
114. here 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 Although 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 ad
115. ial 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 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 Issue Date Page P95 Table 20 User defined and fixed parameters for XSHOOTER ifu acq VLT MAN ESO 14650 4942 20 11 2014 119 of 158 XSHOOTER_ifu_acq Keyword Range Default Value Label in P2PP Free parameters TEL TARG ALPHA 000000 000 T
116. 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 P95 Date 20 11 2014 Page 133 of 158 ER ifu cal SpecphotsStdoffset ER ifu_obs FixedSkyOffset The XSHOOTER_ifu_cal_SpecphotStdOffset Keyword Range Default Value Label in P2PP Free p
117. ilter 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 Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 42 of 158 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 Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 43 of 158 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 P95 20 11 2014 44 of 158 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 1
118. in case the target is too faint to be acquired directly 11 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 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 P95 Date 20 11 2014 Page 65 of 158 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
119. inning 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 4942 Issue P95 Date 20 11 2014 Page 103 of 158 Table 16 long term calibration plan Calibration UVB frames VIS frames f DIR 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 om dark request Set of detector We LINEARITY_UVB_100k FF biases monthly detector monitoring LINEARITY_UVB_400k ca eee monthly detector monitoring Set of detector ae LINEARITY_VIS_ 100k FF biases monthly detector monitoring Set of detector am LINEARITY_VIS_400k FF biases monthly detector monitoring LINEARITY_UVB_100k_1x2 Set of detector monthly detector monitoring LINEARITY_UVB_
120. ion 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 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 P95 Date 20 11 2014 Page 116 of 158 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 mo
121. ir 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 readout 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 M nchen Germany Doc Issue P95 Date 20 11 2014 Page 38 of 158 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 38 12 2x2 slow fast 22 8 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 48 14 2x2 slow fast 27 9 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 ty
122. itions 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 TCCD features 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 20
123. kyflats The most affected filters are the r i z 1 VLT MAN ESO 14650 4942 P95 20 11 2014 93 of 158 The amplitude peak to peak ranges from 2 in the r to 4 in the z filter Eagle ce o rA IAA Paves Se wre ig ey ae P ean 2 i Projection Projection 1 04 1 04 1 02 1 02 8 3 lt lt 2 2 1 Il 0 98 0 98 0 96 165 978 165 974 165 971 165 967 121 815 121 810 121 805 121 801 10 070 10 073 10 076 10 080 26 980 26 982 26 984 26 987 wes wes Fig 7bis Fringing maps inr 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 P95 Date 20 11 2014 Page 94 of 158 eCalibration frames overview and examples Figure 8bis Three color BVI image of a galaxy 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 P95 Date 20 11 2014 Page 95 of 158 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
124. ld Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 79 of 158 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 at 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 sli
125. lit 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 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 gc 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 P95 Date 20 11 2014 Page 113 of 158 7 Reference material 7 1 Templates reference In the following sections all the currently defined X shooter templates are listed with th
126. lit 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 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 Munchen Germany Doc Issue Date Page VLT MAN ESO 14650 4942 P95 20 11 2014 41 of 158 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 f
127. me of 1s XSHOOTER_slt_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 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 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 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 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germ
128. med 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 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 P95 Date 20 11 2014 Page 29 of 158 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
129. n 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 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 airm
130. ndalone 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 P95 Date 20 11 2014 Page 64 of 158 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 Warmup of the lamp for the flexure correction measurement 2 Preset the telescope to the target coordinates and set the adaptor rotator to the chosen position angle 3 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 4 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
131. nds in 3 min exposures and good weather conditions ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Transmission Transmission Transmission Transmission 0 87 gt a ree gt gt 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 P95 Date 20 11 2014 Page 86o0f 158 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 P95 Date 20 11 2014 Page 87 of 158 SDSS i Transmission Transmission 650 700 750 800 850 900 700 800 900 1000 1100 Wavelength nm Wavelength nm Table 2bis A amp G CCD zeropoints
132. ng generic offset template XSHOOTER_img_obs_cal_dist tsf To be specified Hidden Range Defeat _____ DET4 WINI 0 36000 7 TCCD Exposure time DPR C ma yes CALIB Data Prod Cath DPR TECH yes IMAGE Data Prod Tech DPR TYPE yes STD ASTROMETRY 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 TYPE offsets e g OSSO SEQ OFFSET COORDS no SKY DETECTOR SKY Offeei 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 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 Hidden Range Deu Paper T4 WIN1 UITI 0 36000 1 TCCD Exposure time DPR CATG 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 TYPE offsets e g OSSO SEQ OFFSET COORDS no SKY DETECTOR SKY Oki coord type RA DEC X Y SEQ OFF
133. ns 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 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 78 of 158 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 r hoose 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 12 6 fixed in angle or normal SYNCHRONIZED VIS 400k 1x2 each arm or choose another ETC VIS 100k 2x2 value VIS 400k 1x1 VIS 400k 1x2 VIS 400k 2x2 NIR non dest STARE 9999 parallactic UVBRI angle IMAGING GENERIC OFFSET oo UGRIZ or choose another value Table 13 Instrument setup summary ESO Karl Schwarzschi
134. o 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 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 P95 20 11 2014 114 of 158 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 P95 Date 20 11 2014 Page 115 of 158 7 1 2 Examples of position angles and offsets TEL ROT OFFANGLE is the keyword in the acquisit
135. 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 science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc Issue VLT MAN ESO 14650 4942 P95 Date 20
136. 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 detectors 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 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
137. ollowing articles 1 main article Vernet et al 2011A amp A 536A 105V VLT MAN ESO 14650 4942 P95 20 11 2014 15 of 158 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 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 P95 Date 20 11 2014 Page 16 of 158 1 8 News 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 tim
138. on 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 P95 Date 20 11 2014 Page 57 of 158 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 light count is much lower than without the filter and in all cases the corresponding or
139. oo A a iae 2 oe a 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 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 P95 Date 20 11 2014 Page 105 of 158 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 impe
140. or 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 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 9um 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 P95 20 11 2014 37 of 158 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 d
141. ormed 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 www eso org observing dfo quality pipeline status html XSHOOTER More information on the current pipeline problems and limits is available at http Awww 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 orq 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 P95 Date 20 11 2014 Page 111 of 158 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
142. ot 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 P95 Date 20 11 2014 Page 85 of 158 Figure 2bis A amp G CCD quantum efficiency curve A amp G Camera CCD 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 selected 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 ba
143. pe 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 pixels 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 70 19 1x1 slow fast 92 24 0 88 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 P95 Date 20 11 2014 Page 39 of 158 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 x11 slit SCI CAL 0 7 x11 slit SCI CAL 0 9 x11 slit SCI CAL 1 2 x11 slit SCI CAL 1 5 x11 slit SCI CAL 5 0 x11
144. 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 camera 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 P95 Date 20 11 2014 Page 48 of 158 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
145. posures 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 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 SLITSPEC Instrument Mode IFUSPEC SEQ AGSNAPSHOT E F Take an acquisition image before science exposures ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany IFU observations Doc Issue Date Page VLT MAN ESO 14650 4942 P95 20 11 2014 126 of 158 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 Values INS MODE SLITSPEC IFUSPEC Instrument Mode IFUSPE
146. prime z prime U B V R I V G Filter SEQ PRESET yes FT T Preset flag TEL AG GUIDESTAR no CATALOGUE SETUPFILE Get Guide Star from NONE CATALOGUE TEL GSLALPHA 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 ADDVELDELTA 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 arameter Hi n Value La ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 ES Q Issue P95 0 Date 20 11 2014 Page 153 of 158 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 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
147. rfections 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 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
148. 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 Hala 193s Slit 0 9 18 8 s Slit 0 9 40s D2 14s IFU Halo 325 IFU 52 s IFU 60 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 P95 20 11 2014 106 of 158 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 that the slits are uniformly illuminated ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 107 of 158 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 a
149. s 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 eee eee es ean re ee nen XSHOOTER_sit_acq 360 Tel offset AG_EXPOSURE 3 AG EXPOSURE XSHOOTER_ifu_acq 360 Tel offset AG_EXPOSURE 3 AG_EXPOSURE XSHOOTER_sit_acq_RRM 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 P95 Date 20 11 2014 Page 99 of 158 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_slit 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 ti
150. served 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 Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 110 of 158 6 7 The X shooter pipeline 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 t 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 perf
151. sssnnnneennnnnnnnnnnnnne nn 40 2252 SL WIWCGIS aan ken 40 22 6 3 NIR BackgroundS anaseeseaeen 44 2 2 6 4 Optical layout GOSPERDEREENEERERHERELHEENEHREHEREEBECNEEBEREEIPEHEHECHEEHERRHEEFEBELHEEBEBEPEERFBECHELBEBELEE 47 2 2 0 9 DEIECIOr ansehen 48 2 3 Spectral format resolution and overall performances cccccceeeeeeeeeeeeeeeeeeeeeees 51 2 3 1 Sp ctral OPIN ee 51 2 3 2 Spectral resolution and sampling nennen 52 2 3 3 Overall sensitivity an 53 2 4 Instrument features and known problems to be aware Of cccccccccceceeeeeeeeees 55 2 4 1 UVB and VIS detectors sequential readout ccccccccceceecceeeeeeeeeeeeeeeeeeeeees 55 2 4 2 Effects of atmospheric diSPersiOn cccccccccccccccccccccececeeeeeeeeeeeeeseseeeeeeeeess 55 2 4 3 Remanence rn nina 55 2 4 4 COS stds aaa thes icas EUHEOERPEUEERRE EURSUEEPEREEBEESEUERURNONEEEUSEDEEERUEUEEREREEOEUHENENENEEEREEEUREUER 56 2 4 5 Inter order background BEBERPERRPEFPEUFREEELFEHERELECHELEEEFCHFEELLLUREFEELTUUEREEUFERLEEFLECHERELPECRE 57 2 4 6 NIR frames with the K band blocking filter features 57 2 4 7 NIR detector interquadrant cross talk and electrical ghosts 59 2 4 8 Instrument stabilty Ges anna RR 59 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 9 of 158 2 4 8 1 Backbone flOXULES
152. stion 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 Doc Issue VLT MAN ESO 14650 4942 P95 Date 20 11 2014 Page 128 of 158 Table 30 User defined and fixed parameters for th
153. t 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 slit 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 ssrrssnss sn with filter 1238nm 20 without filter 1238nm H Henn 0 0 with filter 1300nm without filter 1300nm with filter 1682nm without filter 1682nm s srn na 0 0m 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 P95 Date 20 11 2014 Page 46o0f 158 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
154. t 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 26 02 2014 30 06 2014 All 20 11 2014 Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 7 of 158 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 2 4 7 2 4 14 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN E
155. tar 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 MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 23 of 158 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
156. te 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 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 ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 81 of 158 The structure of the OB could be like this Slit acquisition stare imaging template1 with filter V 4 exposures of 2s stare imaging 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 More details will be provided in a dedicated document 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
157. th 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 Detector calibrations Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 148 of 158 Table 65 User and fixed keywords for XSHOOTER gen cal Bias
158. ther 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 For example if you will read out in slow unbinned mode and expect to be photon starved in the UVB then according to Table 15 see next page you should make the VIS integration at least 92 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 Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 83 of 158 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 eOverview X shooter remains foremost a set of spectrographs but a simple 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
159. tmospheric 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 background 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 Remnants have been observed in the three arms
160. 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 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 P95 Date 20 11 2014 Page 22 of 158 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 s
161. 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 ESO Karl Schwarzschild Str 2 85748 Garching bei Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 84of 158 Table ibis A amp G CCD characteristics Detector type E2V CCD57 10IE Cooling system Pelletier QE 82 at 580 nm 50 at 380 nm and 820 nm Number of pixels 562x528 Pixel size 13umx13um Pixel scale pixel Field of view 0 1744 0 0016 since P92 at UT3 1 5 x1 5 but filters do n
162. ts 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 P95 Date 20 11 2014 Page 80of 158 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 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 su
163. ts 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 atmospheric dispersion compensators ADCs in the UVB and VIS arms and a warm optical box in the NIR arm 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 P95 Date 20 11 201
164. 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 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 P95 Date 20 11 2014 Page 25 of 158 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 Un
165. ue 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 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 P95 20 11 2014 122 of 158 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 36
166. uest Accurate radial vel calibration 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 Spectro calib In nodding mode in slit mode it is taken every time the photometric 2 2 2 daily A standard instrument is used in IFU mode only when the science performed at night did it Spectroscopic As requested As requested As On request Twilight spectroscopic skyflats skyflats requested Imaging mode A dedicated user manual is available with all the details ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc Issue Date Page a Darks every day monitoring darks DITxNDITXNEXP 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 P95 20 11 2014 102 of 158 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 b
167. ult 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 P95 Date 20 11 2014 Page 135 of 158 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 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
168. ures for VIS det ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 151 of 158 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 P95 Date 20 11 2014 Page 152 of 158 b Template description NIGHTIME IMAGING TEMPLATES Imaging acquisition template also allows blind offset XSHOOTER_mg acq tsf To be specified Parameter Hidden Range Default DET WINLUITI TA A 0 36000 7 TCCD Exposure time DPR CATG ACQUISITION Data Prod Cath DPR TECH IMAGE Data Prod Tech DPR TYPE OBJECT Data Prod Type INS FILT1I NAME u_prime g_prime r_prime i_
169. ut 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 declination 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 Munchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 34 of 158 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
170. vement in the y axis N ESO Karl Schwarzschild Str 2 85748 Garching bei M nchen Germany Doc VLT MAN ESO 14650 4942 Issue P95 Date 20 11 2014 Page 117 of 158 Warning the imaging mode templates will be described later once they will be fully tested and validated 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_slt_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 FI
171. 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 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 P95 Date 20 11 2014 Page 54of 158 UVB arm 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
172. yOffset 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 P95 20 11 2014 68 of 158 onstraint Set Time Intervals demonstration Name Right Ascension Declination Equinox Epoch Class Proper Motion RA Proper Motion Dec Diff RA Diff Dec target_direct_acquisition 10 00 00 000 12 12 12 120 2000 2000 0 Unknown z 0 003000 0 005000 0 000000 0 000000 Informations of the science target in case of dire

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