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1. 35 Parameters of NACO_img_acqMoveToSlit 36 Parameters of NACO_img_acqMoveToMask aa 37 Parameters of NACO_img_acq_SDIMoveToMask eens 38 Parameters of NACO_img_acq Polarimetry 1 0 0 cee ee ee es 39 Parameters of NACO_img_obs_AutoJitter 0 0 0 00 00 epee eee eee 40 Parameters of NACO_img_obs_GenericOffset a 41 Parameters of NACO_img_obs_FixedSkyOffset 0 0 00000 e nee 42 Parameters of NACO_img_cal_StandardStar eee nee 43 Parameters of NACO_sdi_obs_GenericOffset 44 Parameters of NACO_spec_obs_AutoNodOnSlit 0 0000004 NAOS CONICA User Manual VLT MAN ESO 14200 2761 Xi 45 Parameters of NACO_spec_obs_GenericOffset 0 2 0 0000 eee eee 72 46 Parameters of NACO_spec_cal NightCalib 74 47 Parameters of NACO_pol_obs_GenericOf Set eee 76 48 Parameters of NACO_pol_obs_Retarder e 78 49 Parameters of NACO_coro_obs_Stare aa a 79 50 Parameters of NACO_coro_obs_AStro aa 81 51 Parameters of NACO_coro_cal NightCalib 0008 4 82 52 Parameters of NACO_coro_cal_StandardStar 83 53 Parameters of NACO_sdi4_obs_Stare 0 000000 00 beeen 84 xii NAOS CONICA User Manual VLT MAN ESO 14200 2761 Acronyms 4QPM 4QPM_H 4QPM_K AO CONICA DPR
2. Photometry Mag Spectral Type Sr on target 114 4 Observed Magnitude 143 Band V Spectral Type F5 A 4 2 FWHM on reference object 0 082 Transmission 54 7 PSF AO config Reset form Register Object Update Object Cancel Export to NACO ETC Export to P2PP Reset All Figure 30 PS Graphical User Interface e The action area gathering general actions such as requests for optimization or creation of the P2PP parameter file and the HTML file for the ETC B 3 Target amp Instrument Setup The observing wavelength in um can be entered as a filter in which case the wavelength automatically appears or it can be entered directly by selecting free from the list of CONICA filters and then typing the value directly into the space provided The dichroic name can be selected or left free If left free the PS will select the dichroic which maximizes the Strehl which usually means that most of the light will be sent to NAOS If another dichroic is preferable then the dichroic can be selected here Tab 2 gives the conditions under which the various dichroics should be used Users should familiarize themselves with the contents of this table In particular the most critical choice will be between the N90C10 and N20C80 dichroics The former will result in higher Strehl ratios but much lower sensitivity particularly in the K band The N90C10 dichroic can also b
3. List of offsets in X List of offsets in Y Return to Origin Filter Mask Position Camera T F Default NODEFAULT NODEFAULT Double_RdRstRd 1 NODEFAULT NODEFAULT NODEFAULT T NODEFAULT C_0 7_sep_10 NODEFAULT Description Detector Integration Time secs Number of DITs Readout mode Number of exposures per offset position Number of offset positions Offset in arcseconds Offset in arcseconds Return to origin at the end of the template Filter Name Coronagraphic mask Camera Name 84 NAOS CONICA User Manual VLEMAN ESO 14200 2761 6 10 SDI 4 Template 6 10 1 Introduction For SDI 4 observations the readout mode of the detector should be set to either Double _RdRstRd or to FowlerNsamp 6 10 2 NACO_sdi4_obs_Stare This template is used for SDI 4 observations and it moves the telescope alternatively between a fixed ob ject position and a sky position The parameter Number of AB or BA cycles defines the number of times this is done but unlike the NACO_spec_obs_AutoNodOnS1lit NACO_img_obs_AutoJitterOffsetand NACO_img_obs_FixedSky0ffset templates the sequence is ABABAB and not ABBAAB for the example in which the Number of AB or BA cycles is set to 3 This part of the template works identically to NACO_coro_obs_Stare The number of exposures at the object position is defined by the Number of Exposures Object Only parameter The telescope does not offset between these exposures The number of exposure
4. Position Angle 0 deg Position Angle 45 deg 1024 1024 1024 1024 Y Y N E N E Conica FoV Conica FoV 1 1 X 1 1 X Figure 17 Orientation for imaging polarimetry and coronagraphy Left Field orientation on detector at 0 rotation angle on sky Right Field orientation at 45 rotation angle on sky 54 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Position Angle 0 deg Position Angle 45 deg 1024 1024 1024 1024 Y Y Slit Slit E E N Conica FoV ConicaFoV N 1 1 X 1 1 X Figure 18 Orientation for spectroscopic observations Left Field orientation on detector at 0 rotation angle on sky Right Field orientation at 45 rotation angle on sky e For imaging polarimetry and coronagraphy East is on the left X of the images for zero position angle For spectroscopic acquisition East is at the top Y for zero position angle e For imaging polarimetry and coronagraphy North is at the top Y of the images for a zero position angle For spectroscopic acquisition North is on the right X for a zero position angle e Position angle on sky This angle is measured in the standard way i e it is positive from North to East e The slits are oriented along detector rows e For spectroscopy a position angle of zero means that the slit is aligned North South e For polarimetry a position angle of zero means that the mask is aligned East West The tem
5. Depends on the brightness of the source used for AO Not charged to the user Depends on target brightness Depends on target brightness Accurate centering is mandatory On top of the classical ACQ time Rore Add to the exposure time per on off pair per on off pair 44 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 21 Overheads Example 1 Imaging a faint source V 15 for visual WFS or K 10 for IR WES with FowlerNsamp Template parameters Acquisition Template NACO_img_acq MoveToPixel Observation Template NACO_img_obs_AutoJitter DIT 3 seconds NDIT 20 Number of offset positions 60 NEXPO per offset position 1 Readout mode FowlerNsamp Execution time Preset 3 minutes Guide Star Acquisition 0 75 minutes Initial Setup 2 minutes AO acquisition 10 minutes Imaging acquisition 0 5 minutes Sub total Acquisition 16 25 minutes Observation 60 27 20 3 2 127 minutes Total 145 minutes Overheads 141 Observation Number of offset positions x Offset overhead NDIT x DIT readout overhead Table 22 Overheads Example 2 Imaging a bright source V 11 with the visual WFS or K 7 with the IR WES with Double_RdRstRd Template parameters Acquisition Template NACO_img_acq MoveToPixel Observation Template NACO_img_obs_AutoJitter DIT 2 seconds NDIT 30 Number of offset positions 20 NEXPO per offset position 3 Readout mode Double_RdRstRd Execution time Preset 3 minutes Guide Star Acquisition 0 75 minutes
6. aocfg file into a jnps file and then import it as a session B 11 Giving names to session P2PP and PSF files Each time a file is about to be saved one is asked to provide a name The default name is based on the target name but one may want to change it This does not affect the operations and may be convenient for the user However remember the files will be used by Unix based machines so one should avoid special characters spaces brackets etc in the names B 12 User s preferences The Preferences menu gives access to configurable functionalities of the PS which are detailed below e Show tool tips every field in the GUI has an attached tool tip Though very useful when starting to use the PS this may be annoying for more experienced users This option allows one to switch them on off e Set server name this menu item raises a small pop up window that allows one to change the name of the host machine where the PS server can be accessed It is unlikely that normal users will need to use this feature If you do happen to accidentally change the name the server name can be found at http www eso org observing etc naosps doc NAOS CONICA User Manual VLEMAN ESO 14200 2761 99 e Set cache folder you can specify here the name of the directory where the output files are created by the PS the one to be inserted in P2PP OBs are saved The default is your home directory Every change is automatically recorded in the jnps
7. the mask slit wheel which contains various masks for imaging SDI and polarimetry note that now only the Wollaston_00 is available since the Wollaston_45 mask had to be removed to make space for the 4QPM in H and K the coronagraphic masks and the slits for spectroscopy the Fabry Perot wheel which is set to open for non FPI observations the Lyot wheel which includes the ND filters the grism wheel which contains the grisms the prism the SDI and SDI wollastons the wire grid analyzers for polarimetry and the J broad band filter the first filter wheel which contains all the intermediate band IB filters NB 2 17 NB 2 12 and NB 4 05 the second filter wheel which contains all the broad band filters except J the remaining NB filters and the order sorting filters used in spectroscopy e the camera wheel which contains all the objectives 4 1 Imaging Imaging is the simplest mode of CONICA Images can be obtained with a variety of filters and pixel scales 4 1 1 Cameras The characteristics of the cameras of CONICA are described in Table 5 in terms of plate scale and field of view FOV Each camera has a corresponding field mask which is automatically set by the instrument software 4 1 2 Filters All but one of the CONICA filters Tables 6 and 7 are mounted on two filter wheels Transmission curves of several filters are given in Appendix A The J band filter is mounted on a third wheel which also contains th
8. 00 eee ees 67 6 67 SD oia ved hd SBS sa o Book dt ety Take Both chic de Bl cq tale Grog Nhe dee ool 68 6 6 1 Introductionis sa aneso cs ran gh dS cas Ares dye de a a we HO 68 6 6 2 NACO_sdi_obs_GenericOffset 0000000000000 08 68 6 7 Spectroscopic Templates oaos eet ee 70 6 7 1 TIntrodtiction s sao e SS a a ee Se Se wes A 70 6 7 2 NACO_spec_obs_AutoNodOnSlit 0 00 000 eee ee 70 6 7 3 NACO_spec_obs_GenericOffset 000 00 eee ee 72 6 7 4 NACO_spec_cal_StandardStar 0 00 00 eee ee es 74 6 7 5 NACO_spec_cal NightCalib 00 0 0 000 2 eee ee 74 6 8 7 Polarimetric Templates e su sraa a Eee AI LA 75 6 3 Introductions Hi as a a AA AA lve ao 75 6 8 2 NACO_pol_obs GenericOt set 0 00 00 eee ee ee 75 6 8 3 NACO poliobs Retarder Verid A A ee a eee deta a E 76 6 8 4 NACO _pol_cal_StandardStar 000 0 ee 78 6 9 Coronagraphic Templates ee 79 GOL AMtFOMUCHON E ames tn dl de AYRE We TA RS e ee 79 6 9 2 NACO_coro_obs_Stare 2 aaraa a ea a A h a e D r a a aa ea 79 6 9 3 NACO_coro obs Astro 80 6 9 4 NACO_coro_cal_NightCalib a 81 6 9 5 NACO_coro _cal_StandardStar a a 82 6 10 SDI 4 Template a rare aa eae e a a a ea ee ee 84 6 10 1 Introduction 24 aa a a ae a PS AA oe do a BA RE ee BR Se Ew ee 84 6 10 2 NACO _sdi4 obs Stare ee 84 7 acknowledgements 86 A Filter Transmission Curves 87 A 1 CONICA Broad band imaging and order s
9. 6 5 7 Wollaston_45 is now offered ae May 2005 1 1 5 14 5 17 6 10 4 Update for P76 related to HWP PRM Trine tpt oft dp einer Bo 26 May 2005 42 Inserted an image ofthe SDIFOV 4 01 Sep 2005 13 1 3 5 6 Update for P77 Tab 9 4 2 5 6 all correction of few typos Pa 18 Dee 3005 1363 Presenting new coro template 01 Mar 2006 T T 1 37 Update for P78 Se ae 1v NAOS CONICA User Manual VLT MAN ESO 14200 2761 Change Record Cont ed Section Parag affected Reason Initiation Documents Remarks 78 12 Jun 2006 Update of changes for P78 Adjustment of the performance quoted Changes for Pre Imaging Update for LGS operation 6 5 2 6 5 7 6 6 2 6 6 3 6 7 2 6 7 3 Update of keywords Update due to LGS mode in PS 78 23 Jun 2006 Typos Update version amp period number Adding a comment on FS limits check Update for PRE_PSF imaging Explaining the FPI order parameter i Specifying JNPS working platforms Clarifying parameters 01 Sep 2006 1 1 1 3 6 1 Update version amp period number 79 19 Dec 2006 1 3 Introduce the PS Ay modification for phase II B 5 B 5 1 B 5 2 B 6 B 8 B 9 Smoothing the english Fig 23 Replaced by the newest panel version B 5 3 Definition of the new PS A y parameter 05 Mar 2007 First page Change version Presentation of changes for P80 Update of new modes Update to suit the observatory calibration plan Corrected the time for LGS pola ACQ Update after commissioning
10. A e where are random offsets In order to avoid the possibility of overlapping spectra should be smaller than half of the nod throw The random offsets are generated inside an interval defined by the parameter Jitter Box Width in arc sec Offsets are randomly distributed between 2 tterBoxilidth anq JitterBoxilidth Tt is strongly recom NAOS CONICA User Manual VLT MAN ESO 14200 2761 71 mended to define some non zero value for the Jitter Box Width parameter as this allows one to get several images with the spectra lying at different positions on the detector However it should be smaller than the Nod throw otherwise spectra on either side of the throw could overlap NACO_spec_obs_AutoNodOnSlit 1024 1024 Y Acquisition Position Jitter Box po 6 2 3 14 5 l Nod Throw E Slit Angle 0 degrees N CONICA FOV S27 28 1 1 X Figure 23 An illustration of how the NACO_spec_obs_AutoNodOnS1lit template works with Jitter Box Width 5 Return to Origin T F T Number of AB or BA cycles 3 NEXPO per offset position 1 Nod throw 15 To better exploit the jittering facility offered by this template it is also recommended to define the Number of AB or BA cycles to some value higher than 1 e g 4 or 5 so as to get several AB pairs of images with the spectra lying at different positions across the array If the parameter Jitter Box Width is set to zero then the template wil
11. In the first case the field selector FS has to move from where it was when the NAOS AO loop was last closed In the second case the FS does not move The field of view of the FS is a bit less than 2 arcminutes If the offset sequence is such that the positions at which the loop needs to be closed is outside this region the observations will fail It is not possible for the system to know beforehand what offsets it will be asked to perform so if it encounters an offset command which would move the FS beyond its limits it will politely refuse Template parameters which would lead 36 NAOS CONICA User Manual VLEMAN ESO 14200 2761 to that happening are checked for during OB verification When small telescope offsets are used less than one arc minute the telescope keeps the same active optics star If however large telescope offsets are used several arcminutes the active optics star changes Never theless when returning to the science target and closing the AO loop on the same reference source any offsets that might be caused by changing guide stars should be compensated by NAOS 5 6 Chopping and Counter Chopping Important in P81 chopping is not supported 5 7 Target Acquisition 5 7 1 Imaging Although the pointing accuracy of the VLT is very good some of the CONICA fields of view are quite small For the smaller fields of view S13 S27 and L27 we recommend that users use the NACO_img_acq MoveToPixel template This templ
12. The dashed line connecting position 9 with 5 is the offset done after the 9th and 18th exposures Position 5 corresponds to the position the target was acquired This sequence has been designed so that the entire field of view is covered in Y The offsets are relative to the previous position are in X and Y and are defined in arcsec Additionally the observation type can be defined for each image and is entered as a list in the parameter Observation Type 0 or S O stands for Object and assigns the DPR TYPE header keyword to OBJECT S stands for Sky and assigns the DPR TYPE header keyword to SKY The AO loop is closed for the former and open for the latter The total number of spatial offsets is defined by the parameter Number of offset positions This num ber can be different from the number of elements in the aforementioned lists If the number of spatial offsets is larger than the number of elements in a list the list is restarted from the beginning as many times as needed until the correct number of offsets have been done These lists can have any length however having lists of different lengths can become extremely confusing It is good practice to use lists of equal length or lists with only one value if one parameter is not changed The total number of exposures is given by NEXPO per offset position xnumber of half wave plate angle x Number of offset positions Unlike other templates this template does not have a Return
13. than in other LW filters because the background in M is considerably higher and this means that the integration time has to be reduced which can only be done by windowing the array Additionally there are two neutral density filters ND_Long which can only be used with LW filters and ND_Short which can only be used with SW filters These filters are mounted in another wheel so they can be used in parallel with other filters to reduce the flux of extremely bright sources The intensity of sources are reduced by factors of 80 and 50 for the ND_Short and ND_Long filters respectively Table 6 List of CONICA broad band imaging filters FWHM 4 1 3 Calibration plan For imaging observations a variety of calibration frames will be taken archived and updated at regular intervals The what when and how of calibrations is described in detail in the NACO Calibration Plan http www eso org instruments naos index html Documentation e Nightly zero points provided it is clear in J H and Ks with the S27 objective and visual dichroic Zero points in L and M with the L27 objective and zero points in the J H and Ks filters with either the S13 or S54 objectives and other dichroics will be taken when these modes are used Observations in J H and Ks will be done with the detector in Double_RdRstRd and observations in L and M will be done in Uncorr Zero points in all other filters including the FP and readout modes are not supported
14. will be observed with the AO loop closed For the sky positions the AO loop will be open Table 41 describes the parameters of this template By default there is no telescope offset before the first exposure If the parameter Return to Origin T F is set to true T the telescope moves back to its original position at the end of the template If not the telescope is not moved The Number of AB or BA cycles defines the number of OBJECT SKY or SKY OBJECT cycles to be executed These cycles are executed in ABBA sequences E g if Number of AB or BA cycles is set to 3 6 exposures will be taken in an ABBAAB sequence NAOS CONICA User Manual VLEMAN ESO 14200 2761 65 NACO_img_obs_GenericOffset 1024 1024 E N Position Angle 45 deg CONICA FOV 28 for S27 1 1 X Figure 21 A second illustration of how the NACO_img_ obs_GenericOffset template works As with the previous example exposures 1 and 5 occur at the same place and the telescope will not return to the origin after the eighth exposure The parameter settings for this example were NEXPO per offset position 1 Number of offset positions 8 Return to Origin T F F Camera S27 Observation Type 0 or S O Offset Coordinates SKY List of offsets in RA or X 040 400 40 List of offsets in DEC or Y 0080 8 808 The template provides the possibility of rotating the instrument between object and sky frames so that pupil ghosts can be mi
15. 2007 5 for P79 this is the hardcoded epoch of the reference target The epoch of the science target is a free parameter to set between 1850 amp 2100 The target and AO reference star can have different proper motion It is however assumed that the coordinates are given for the same equinox B 4 Sky Conditions The user characterizes the observing conditions via two parameters the seeing at Zenith and measured at 0 5um and the airmass The on axis quantities such as the seeing on the reference are automatically computed from these two parameters and some assumptions about the average wind speed and isoplanatic angle on Paranal The Fried parameter ro and the isoplanatic angle 6 are also displayed All on axis quantities are computed at 0 5 um B 5 Reference Objects The information about reference objects is gathered on the right hand part of the main GUI For LGS operations the natural guide star for tip tilt correction TTS has to be specified Ease of operations requires that only one TTS can be specified per LGS OB B 5 1 Handling several reference objects It is possible to keep a list of several possible reference objects for observations in NGS and work alterna tively with each of them The list of reference objects is shown as a table at the top of the form containing all the data pertaining to the reference object Each row corresponds to a reference object showing its name if it has been provided and its a
16. 81 24 Aug 2007 First page Change version Acronyms list 1 2 1 3 Presentation of changes for P81 4 4 4 4 1 4 4 2 Update of new modes 2 2 2 4 4 1 3 5 6 Update of non offered modes Modified by P Amico 81 1 22 Dec 2007 First page Change version 1 2 3 4 5 Included SDI 4 characterization of 4QPMs 6 App B LGS guidelines templates description Modified by P Amico NAOS CONICA User Manual VLT MAN ESO 14200 2761 v Contents 1 Introduction 1 1 1 Current version of this User Manual eee ee eee 2 1 2 Changes for period 81 a 2 2 Observing with Adaptive Optics in the Infrared 3 ZA gt Adaptive Opt tt a D Bde ees 3 2 1 1 Atmospheric turbulence o e A ee 3 221 2 2 Adaptive OPliCS 0 400 eane el Da aa a 3 2 2 Infrared Observations with an AO system a 4 2 2 1 Transmission and background e 5 2 2 2 Background subtraction oaaae 5 2 23 ASPEC OsSCOPY de Beet eh ad aa e a 7 3 NAOS 8 BA OVEIVIEW ek ela oko a Kw ut abel ddl deere Mee wetted eh vee eh acne amp 8 3 2 NAOS Performance e s a e ad ee we 9 3 3 Anisoplanatism aaa ee 9 3 4 Laser Guide Star facility LGSF e 10 4 CONICA 12 l A A RA 12 AE Cameras e ap e a di do ed ra latas 12 A al Bate lec es E O 12 4 1 3 Calibration plan 2 ee 14 4 124 Pipeline a GE a a ee Ge Gale ow Gs 16 4 1 5 Fabry PerotImager oana ee 16 4 2 Simultaneous Differential
17. A A i 30 4 6 2 Pipeline A ties oe ee a a eld 30 4c o CONICA Detector enc ua arta he eb ae dh Geta bea ow ee a he as 31 4 7 1 General characteristics 31 4 7 2 DITandNDIT art ld ah a Eom bo te A Ged as ie dood Ses gs 32 4 7 3 Readout Modes and Detector Modes o a aoaaa o e 32 Observing with NAOS CONICA at the VLT 34 Salt TOVERVIEW a a DA AS ine Abe I Rb ee ee ee ls 34 5 2 Visitor ModeOpetations sle eas a tad AMR Sad Se A ee Bek we de ks 34 5 3 Active optics and adaptive optics 2 e 34 5 4 The Influence ofthe Moon 0 0 00 ee ee 35 5 5 Telescope control aei 64 ce ia a a aa a a a ee we E e 35 5 6 Chopping and Counter Chopping 0 0 002 a 36 5 7 Target Acquisition 2 ee 36 A Uma ging lt n cece a wk ae a e ee Ge a a Go i a ow s 36 lil SPCCtrOscOpy drid SNe ey hae Rete a ts Neen ae Ah ee eed 36 Ll Coronasraphy tE i ae Ue 36 hie S DI 6 Seer tok IE Ae a AS 36 Deh POLINESIA BG EE a Ae AS ee IA do 36 5 8 Pre Imaging n a 3 ce A ek A A A E 37 5 9 Finding Charts README Files and OB Naming Conventions 37 5 10 Reference Sources for Wavefront Sensing 0 000000 ee eee 38 5 11 Measuring the Strehl Ratio and OB Classification in Service Mode 38 1121 PSF Reference Stars sox Gr gegen et he Sa a A 38 5 12 Recommended DITs and NDITs 00 002 cee ee ee 39 5 43 TR backgrounds n meor fa aly acted a de a 39 5 14
18. H Ks and L band filters respectively The L band filter is only offered in spectroscopy for imaging applications users should use the L filter 3 The resolution is computed for the 86mas slit For slitless spectroscopy and for spectroscopy with the 172mas slit the spectral resolution is set by the PSF 4 3rd order overlap at 3 90 microns e Detector darks Darks are taken at the end of each night with the DITs and readout modes used during the night Special note about the prism calibration For the L27_P1 mode given the low resolution at 1 micron and the high background at 5 microns the normally used telluric standards B dwarfs and solar analogs are not suitable As a consequence for this mode two telluric standard stars will be taken as part of the calibration plan One star adapted to the short wavelength calibration and one for the L amp M calibration The arc lamps cannot be used to calibrate the dispersion of the prism modes At long wavelengths there are no visible arc lines at short wavelengths the lines are severely blended One can take spectra with the NB and IB filters to define pseudo arc lines The RMS of the fit is relatively large 10 nm The fit is only good between the bluest and reddest narrow band filters currently 1 04 and 4 05 microns Beyond 4 5 microns one needs to use the telluric absorption features in the spectra of bright stars This fit is more satisfying than the fit done with pseudo
19. Imager 2 0 0 00 00002 2 eee ee ee 16 43 Coronagraphy e ese bers es et hook yk A Mie Gh Me 16 4 3 1 Radial attenuation oaa ee 19 AL sCOMWast soa g aa a tye ae olde a eee To BV A He aa Se dia ES A Sava ge tah 19 A 3 3 ChrOmaticity gt ai BR Ae eae AA AA ne AAA 19 4 3 4 Comparison with the classic Lyot masks o oo 21 4 3 5 Observations strategy with 4QPMs 2 2 200 002 ee 21 4 3 6 Calibration plan 2 2 ee a 22 430 Night flat Tields 4 25 it a a A Lee Se SG ee Gwe EA ek 22 43 80 Pipeline 28 a5 rasa Ba Ba a Mots art cleo eR a ee eo es 22 4 4 Simultaneous Differential Imaging plus coronagraphy o o o 22 4 4 1 Contrast with SDIH4 A 23 4 4 2 Tests with 4QPM SDI 4 and rotation 2 20 2 2 000000 002 eee 24 4 4 3 Calibration plan and night flats 2 ee ee ee 26 4 4 4 Night flatfields o eran AN ee ee a a 26 4 45 Pipelines oa bee ee Eh ee ee bs a Gee ea Ye E T 26 45 Spectroscopy sosie 2 4 sok fleck Old Boke wha Aaa ig dd Gwe Get sla dk oe Slee ed 26 ASL SMS a A kao ot hg A hee a ay Qa a de alk GO Sh 26 4 5 2 Spectroscopic mod s s aa k e a a a aa a a a aa eara a aa aa a 27 4 3 3 Calibration plan ci tt Be ee a Ne Sa Ane N a Ani 27 4 5 4 Nighttime arcs and flat fields oa aaa a 29 AS Pipeline E A hg 29 vi NAOS CONICA User Manual VLEMAN ESO 14200 2761 4 6 A A NN eS 29 4 61 Calibration plani 42 05 apta ad
20. Initial Setup 2 minutes AO acquisition 5 minutes Imaging acquisition 0 5 minutes Sub total 11 25 minutes Observation 20 27 2 16 3 30 2 0 7 80 3 minutes Total 91 6 minutes Overheads 53 Observation Number of offset positions x Offset overhead NEXPO per offset position 1 x time between frames without offsets NEXPO per offset position x DIT x NDIT readout overhead NAOS CONICA User Manual VLEMAN ESO 14200 2761 45 Table 23 Overheads Example 3 Imaging a bright source in the L band V 11 for visual WFS or K 7 for IR WES with Uncorr Template parameters Acquisition Template NACO_img_acq MoveToPixel Observation Template NACO_img_obs_AutoJitter DIT 0 2 seconds NDIT 150 Number of offset positions 120 NEXPO per offset position 1 Readout mode Uncorr Execution time Preset 3 minutes Guide Star Acquisition 0 75 minutes Initial Setup 2 minutes AO acquisition 5 minutes Imaging acquisition 0 5 minutes Sub total 11 25 minutes Observation 120 27 150 0 2 114 minutes Total 125 minutes Overheads 108 Observation Number of offset positions x Offset overhead DIT x NDIT Table 24 Overheads Example 4 Spectroscopy of a faint source with FowlerNsamp Template parameters Acquisition Template NACO_img_acq MoveToSlit Observation Template NACO_spec_obs_AutoNodOnS1lit DIT 300 seconds NDIT 1 Number of AB or BA cycles 6 NEXPO per offset position 1 Readout mode FowlerNsamp Return
21. NGS Otherwise move to LGS Chopping observations are impossible in LGS mode thus M band observations cannot be performed NAOS CONICA User Manual VLEMAN ESO 14200 2761 43 Table 20 Overheads Description Overheads Acquisition Templates Telescope Preset Guide star acquisition Initial setup NAOS CONICA AO acquisition Strehl measurement Imaging acquisition Polarimetric acquisition Spectroscopic acquisition Coronographic acquisition SDI 4 acquisition LGSF acquisition 3 minutes 0 75 minutes 2 minutes 5 10 minutes 4 minutes 0 5 minutes 1 minute 1 5 minutes 2 3 minutes 10 minutes 10 minutes Observation Templates Readout overhead per DIT FowlerNsamp Readout overhead per DIT x NDIT Double_RdRstRd Readout overhead per DIT Uncorr Telescope Offsets NAOS header Stop and Start AO Start and completion overheads for IRACE 1 2 3 4 typical offset 2 4 time between frames without offsets Change in instrument configuration FP setup HWP in or out HWP angle setup Rotator offset for polarimetry and SDI Re centering for 4QPM and SDI 4 All observations using chopping Night time spectroscopic flats Night time spectroscopic arcs Night time coronographic flats 2 seconds 0 7 seconds negligible 9 seconds 7 seconds 2 seconds 9 seconds 27 seconds 16 seconds 1 minute 10 seconds 30 seconds 15 seconds 1 2 minutes 2 minutes 30 6 minutes 6 minutes 6 minutes Comments
22. Polarimetry of a bright source with the Wollaston amp HWP Template parameters Acquisition Template Observation Template NACO_img_acq Polarimetry NACO_pol_obs_Retarder DIT 10 seconds NDIT 6 Number of offset positions 5 NEXPO per offset position 1 Readout mode FowlerNsamp List of HWP Angle offsets 0 22 5 Execution time Preset 3 minutes Guide Star Acquisition 0 75 minutes Initial Setup 2 minutes Setting the HWP in out 1 minute AO acquisition 5 minutes Polarimetric acquisition 1 minute Sub total 12 75 minutes Observation at 0 degrees 5 27 6 10 2 8 3 minutes HWP rotation 0 25 minutes Observation at 45 degrees 5 27 6 10 2 8 3 minutes Total 29 6 minutes Overheads 196 l At the beginning of each template the HWP is set into the beam and then moved away at the end producing an extra minute overhead per template 2 Observation Number of offset positions x Offset overhead NDIT x DIT readout overhead 48 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 27 Overheads Example 6 SW Coronography of a bright source with Double RdRstRd Template parameters Acquisition Template NACO_img_acq MoveToMask Observation Template NACO_coro_obs_Stare Number of AB cycles 2 DIT 10 seconds NDIT for the OBJECT positions 6 Number of Exposures Object Only 10 NDIT for the SKY positions 5 Number of offset positions Sky only 4 Readout Mode Double_RdRstRd Execution time Preset 3 min
23. SDI uses special templates to acquire see Sec 6 4 3 and observe targets 6 6 2 NACO_sdi_obs_GenericOffset This template is used exclusively with the SDI and SDI modes It is similar to the NACO pol_obs GenericOffset template in that it allows one to rotate the field of view as well as offset the telescope At each rotator angle the telescope offsets according to a user defined list Offsets are defined with the pa rameters List of offsets in XandList of offsets in Y They are relative to the previous position are in detector co ordinates and are defined in arcsec Additionally the observation type can be defined for each image and is entered as a list in the parameter Observation Type O or S O stands for Object and assigns the DPR TYPE header keyword to OBJECT S stands for Sky and assigns the DPR TYPE header keyword to SKY The AO loop is closed for the former and open for the latter The total number of spatial offsets is defined by the parameter Number of offset positions This num ber can be different from the number of elements in the aforementioned lists If the number of spatial offsets is larger than the number of elements in a list the list is restarted from the beginning as many times as needed until the correct number of offsets have been done These lists can have any length however having lists of different lengths can become extremely confusing It is good practice to use lists of equal length or lists with on
24. ae 87 29 CONICA Neutral density filters 2 2 0 00 0000000000000 000 88 30 PS Graphical User Interface 20 0 0 ee 90 31 V Extinction Curve oi chi hee SOP PP OY ee ae ee Re eS 94 32 Trackmetables sani earns ara rd Dar Ban add Whee Sa aoe ae a hd ed 95 33 Performance Sub panel io aa a ee DA AE Be se em Bea Ae 95 34 AO configuration GUL ap anid de ae eee deat bn A a eae ed a 96 33 PSE pronles ia ea oe PS eas SP Ad Sete 97 x NAOS CONICA User Manual VLT MAN ESO 14200 2761 List of Tables 1 Main modes and parameters of NAOS CONICA oo o o 2 NAOS dichroics beamsplitters ee 3 Wavefront sensors characteristics o o o 4 Summary of NACO Strehl ratios e 5 CONICA Cameras escocia e a i a e 6 CONICA broad band filters 2 o o e 7 CONICA narrow band filters o o ee 8 Diameter of coronagraphic masks e 9 VCONICA SIS se So hore Sel Ay heh id re dk de Pe da Meme ee og 10 Long slit grism spectroscopic modes o oo ee 11 Newspectroscopic modes 12 Beam separations of the Wollaston prisM_ o e e 13 Wi GAS ioe gin a A de a GEE ee S 14 CONICA detector ii coros cha do BH AR Ae et AA AE io ada oes a 15 CONICA detector readout modes ee 16 Recommended DITSandNDITS 0 000 2 eee ee ee 17 IRsBackeroundss a pane ee a ere ao eee A AAA ADA aa 18 Recommended magnitude range for sta
25. applied to service mode observations 5 10 Reference Sources for Wavefront Sensing The brighter the reference source is and the closer it is to the science target the better the correction will be It can even be the science target itself if it is sufficiently bright and point like Whenever possible several reference sources should be chosen in order to avoid acquisition problems due to binarity faintness or proper motion of the reference source The Guide Star and 2MASS catalogues can be used to find suitable references However for LGS observations to ease the development of operations the user is restricted to a single Tip Tilt Star per LGS OB at least for Period 78 In general the visual WFS will be used as this ensures that the largest fraction of IR light enters the science channel The IR WFS should be used for very red sources V K gt 6mag which could otherwise not be observed with NAOS CONICA or for which the IR WFS provides a better correction 5 11 Measuring the Strehl Ratio and OB Classification in Service Mode To help the observatory determine whether or not an OB has been successfully executed in service mode the Strehl Ratio of the reference source will be measured with the NB_2 17 filter during acquisition The measurement during the acquisition process is automatic Users do not have to worry about it In previous periods we had asked users to include the NACO_img_cal_Strehl at the end of each OB This template i
26. are available at http www eso org observing p2pp ServiceMode html the following NAOS CONICA requirements apply e The field of view of all finding charts must be 2 by 2 in size with a clear indication of field orientation e All wavefront reference stars must be clearly marked according to the way they are ordered in the preparation software They should be marked R1 R2 R3 etc e For imaging the field of view of the selected camera must be drawn e For polarimetric and coronographic observations the field of view of the selected camera must be drawn and the object that is to be placed behind the mask in the case of coronography or centered in the mask in the case of polarimetry should be clearly indicated e For long slit spectroscopy the slit must be drawn e For slitless spectroscopy a 14 x 14 arcsecond box should be drawn e For spectroscopic templates the reference star used for preliminary slit centering must be identified e For PSF reference stars the OB name must be prefixed with the string PSF _ e For pre imaging the OB name must be prefixed with the string PRE_ e For PSF observations which are to be done as pre imaging the OB name must begin with PRE_PSF_ 38 NAOS CONICA User Manual VLEMAN ESO 14200 2761 e The magnitude of the brightest object in all fields including standard stars must be explicitly given in the README file or otherwise indicated on the Finding Charts See Sec 5 15 for the limits
27. at which WF errors can be measured processed and corrected the server loop bandwidth The performance of an AO system is also directly linked to the observing conditions The most important parameters are the seeing or more explicitly rg and To the brightness of the reference source used for WFS and the distance between the reference source and the object of interest In case of good conditions and a bright nearby reference source the correction is good and the resulting point spread function PSF is very close to the diffraction limit A good correction in the K band typically corresponds to a SR larger than 30 At shorter wavelengths particularly in the J band or in the case of poor conditions or a faint distant reference source the correction is only partial the Strehl ratio may only be a few percent 4 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Observed object Plane wavefront O i fe E Atmospheric turbulence i 1 Corrugated wavefront 7 Uncorrected image Deformable mirror Tip tilt mirror 14 Real Time RX Computer A op ecas Wavefront Beam splitter o sensor v AO corrected image lt gt Corrected wavefront Camera high resolution image Figure 1 Principle of Adaptive Optics 2 2 Infrared Observations with an AO system Observing in the IR with an AO system is in broad terms very similar to observing
28. by the calibration plan and users should prepare the necessary OBs These calibrations aim to provide a photometric accuracy of 5 Should users need higher accuracy NAOS CONICA User Manual VLEMAN ESO 14200 2761 15 Table 7 List of CONICA narrow and intermediate band filters EWAMIyan they should provide OBs that will be executed either immediately before or after their observations In that case the time spent doing these observations will be charged to the user e Extinction coefficients for J H and Ks filters The observatory does not measure extinction every night Instead the observatory has calculated the average extinction from data than have been taken since operations began e Twilight Flat Fields in all filters with the exception of the FP Observations in J H and Ks will be taken with the detector in Double_RdRstRd observations in M L NB 3 74 and NB 4 05 will be done in Uncorr and observations with the remaining narrow or intermediate band filters will be done in FowlerNsamp Because of the difficulty in taking twilight flats with NACO some setups filter objective may be missed In these cases the daytime lamp flats can be used as an alternative e Lamp flats in all filters including the FP objectives and readout modes with the exception of M L NB _3 74 and NB_4 05 e Detector darks in all readout modes and DITs as required 16 NAOS CONICA User Manual VLEMAN ESO 14200 2761 4 1 4
29. by 50 in the Ks band and 40 in the H band 4 3 2 Contrast Contrasts were measured on the PSF fiber for the 4QPM_K and the 4QPM_H Azimuthally averaged radial profiles are shown in Figure 10 and provide an averaged contrast Another metric commonly used is the maximum attenuation which refers to the ratio of the maximum intensity in the PSF image to that of the coronagraphic image Although maximum intensity is at r 0 on the PSF it is located at 1 5 2 A D on the coronagraphic image Radial contrast does not reflect directly this value because of azimuthal averaging The maximum attenuation is about 100 a little bit more in the H band probably because the Lyot spot is larger with respect to A D at shorter wavelengths This is comparable to the result obtained in 2004 with the first 4QPM implemented in NACO In this case the limit of contrast is set by the residual static aberrations likely originating from non common path aberrations 4 3 3 Chromaticity Phase shifts as provided by phase masks are chromatic However the chromaticity effect must be balanced with other sources of degradations Chromaticity turns out not to bean issue for NACO Even with the fiber source we observed very small variations as a function of the filter bandwidth as shown in Figure 11 The attenuation reaches a factor 60 70 in both Ks and NB 2 17 filters Under atmospheric seeing the effect of chromaticity is totally negligible and a 4QPM designed for the K band can be
30. further away Roll averaging improves also the detection capability of the instrument dashed red The standard SDI processing which consist in 2 observations at of 2 roll angles separated by 33 is also given in blue but for 25 apart This result in a small improvement with respect to SDI green line Another technique which is called double roll subtraction has been tested dashed blue It consists in using NAOS CONICA User Manual VLT MAN ESO 14200 2761 25 Q SD e 3 4th of the doto SDI roll SDi ref 3 4th of the doto SDi ref roll 3 4th of the Yoto SDI Stondord roll subtraction Secs deg SD double roll subtraction 2 5 detection level Angular distance in arcseconds Figure 15 5 o detection level for different processing techniques 4Q and 4Q ref stand for direct corona graphic imaging respectively not using and using reference subtraction For all the lines that are called SDI we are studying the spectral subtraction image at 2 1 575um image at A 1 6254 SDI and SDI roll show the results of SDI subtraction with and without roll averaging It is the same for SDI ref and SDI ref roll but using also the subtraction of the SDI image of a reference star at the same parallactic angle The SDI double subtraction is described in details in the text For the detection level estimation we supposed that the companion has a contrast of 100 in the methane band no flux in the image at A 1 625
31. is a factor 10 smaller than ISAAC Hence it will take 100 times longer to reach background limiting performance Additionally the fields of view are smaller so large scale changes in the sky background are less noticeable in CONICA than in ISAAC Thus the typcial integration time and the typical amount of time between telescope offsets will be larger for CONICA NAOS CONICA User Manual VLEMAN ESO 14200 2761 5 2 2 1 Transmission and background The transmission of the Earth s atmosphere in the 1 5um region is shown in Fig 2 The X J H K L and M bands correspond to atmospheric windows which are approximately centered at 1 1 25 1 65 2 2 3 6 and 4 8 um The absorption is mostly due to water and carbon dioxide and it varies with zenith distance and the amount of water vapour In regards to observations with NAOS CONICA the sky background can be split into two regions Below 2 2 um the sky background is dominated by OH emission that originates at an altitude of 80 km At longer wavelengths the thermal background of the atmosphere and telescope dominate 2 2 2 Background subtraction Subtraction of the background is critical to the success of observing in the IR and special observing techniques have been developed to do it The techniques depend on the type of observation and on the wavelength region at which one is observing For imaging observations shortward of 4 2 microns and for regions that are relatively uncrowded
32. template List of Position Angle Offsets NODEFAULT List of rotator offsets in degrees Filter NODEFAULT Filter Name Neutral density filter Full Neutral density filter Polarizer Grism wheel Wollaston_00 Polarising element Camera NODEFAULT Camera Name only The template can be restarted with another orientation on the sky for another series of exposures At least two different orientations separated by 45 degrees are required for computing the Stokes parameters To image the entire field of view at one position angle one must take great care with the offsets The opaque and transmitting parts of the mask have slightly different widths The opaque strips have a width of 3 9 arcsec and the transmitting strips have a width of 3 1 arcseconds An example of how one may choose to image the entire field of view is given in Fig 25 The total integration time excluding overheads is defined in seconds by DIT x NDIT x NEXPO per offset position x Number of offset positions x the number of rotator positions 6 8 3 NACO_pol_obs_Retarder This template is used for imaging polarimetry without chopping exclusively with the half wave plate It can be used with all filters with the exception of J and M and with either a Wollaston prism or a wire grid polarimeter This templates works with defined generic offsets It can follow any of the following acquisition tem plate NACO_img_acq_MoveToPixelor NACO_img_acqPolarimetry The latter must be used if
33. that uses the Wollaston prism A drawing of the polarimetric mask is displayed on the RTD and is superimposed on the image of the field The centering of the target is then done interactively Acquisition must be done with the L27 objective for LW filters or the S27 objective for SW filters The subsequent polarimetric templates allow one to set the angle before each template starts Table 38 describes the parameters of this template 60 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 38 Parameters of NACO_img_acq Polarimetry P2PP label Default Description DIT NODEFAULT Detector Integration Time secs NDIT NODEFAULT Number of DITs PSF reference T F F PSF reference T F RA offset arcsec 5 RA offset for fixed pattern arcsec DEC offset arcsec 5 DEC offset for fixed pattern arcsec Position Angle on Sky 0 Position angle in degrees Add Velocity Alpha 0 Additional tracking vel in RA Add Velocity Delta 0 Additional tracking vel in DEC Filter NODEFAULT Filter Name Neutral density filter Full Neutral density filter Camera NODEFAULT Camera Name Which Polarimetric Mask Wollaston_00 Polarimetric mask Type of AO Observation LGS NGS NODEFAULT LGS or NGS observation type NAOS parameter file NODEFAULT NAOS parameter file 1 Tn arcsec sec This template records an image of the field after the acquisition has been completed If three images are recorded then the first two are images of the reference and they a
34. the number of elements in the aforementioned lists Lists do not need to have the same length If the number of exposures is larger than the number of elements in a list the list is restarted from the beginning as many times as needed until the correct number of frames have been acquired The lists can have any length however having lists of different lengths can become extremely confusing It is good practice to use lists of equal length or lists with only one value if one parameter is not changed The template provides the possibility of rotating the instrument between object and sky frames so that pupil ghosts can be minimised all object frames have the same position angle on sky The technique has proved to be efficient with SOFI and ISAAC For NAOS CONICA it is not required for observations with the SW filters but it may be needed for the LW filters For mosaics it should be set to False At the end of the template the telescope is returned to the original position if the parameter Return to Origin T F is set to true T If not the telescope is not moved at the end of the template Figs 20 and 21 illustrate how this template can be used The total integration time is defined in seconds by DIT x se of offset positions i NDIT i x NEXPO per offset position 6 5 4 NACO_img_obs_FixedSkyOffset This template moves the telescope alternatively between object and sky positions The object positions are
35. to Origin T F flag By default at the end of the template the telescope returns at the original position It is important to remember that for technical reasons the HWP is moved into the beam and set to its zero position at the beginning of the template and then it is moved out of the beam at the end of the template This introduces an extra 1 minute overhead 78 NAOS CONICA User Manual VLEMAN ESO 14200 2761 per template Table 48 describes the parameters of this template Table 48 Parameters of NACO_pol_obs_Retarder P2PP label Default Description DIT NODEFAULT Detector Integration Time secs NDIT NODEFAULT Number of DITs Readout mode Double_RdRstRd Readout mode NEXPO per offset position 1 Number of exposures per offset position Number of offset positions NODEFAULT Number of offset positions Observation Type O or S NODEFAULT O is with AO S is without List of offsets in X NODEFAULT Offset in arcseconds List of offsets in Y NODEFAULT Offset in arcseconds List of HWP Angle Offsets NODEFAULT List of Half Wave Plate angle in degrees Filter NODEFAULT Filter Name Neutral density filter Full Neutral density filter Polarizer Grism wheel Wollaston_00 Polarising element Camera NODEFAULT Camera Name The template can be restarted with another orientation on the sky for another series of exposures At least two different half wave plate orientations separated by 22 5 degrees are required for computing the Stokes param
36. to choose the name of the file on your local disk This operation is performed by sending the appropriate request to the central server where your PSF file has been stored under a unique name Depending on your local installation the file retrieval may take a few seconds The other quantities which are outputs of the optimization are e The Strehl ratio is expressed as a percentage It is derived from the PSF and as such it is linked to the observing wavelength The on axis Strehl ratio gives an estimate of the correction of the optical beam NAOS CONICA User Manual VLT MAN ESO 14200 2761 97 Resultin g Pe rformance Point Spread Function on target y x axis y max 0 0296 FWHM X 0 094 Dismiss FWHM Y 0 073 Dismiss Sr 15 30 0 96 0 80 0 64 0 48 0 32 016 0 00 016 0 32 0 48 0 64 0 80 0 96 arcsec Figure 35 Pop up window showing the PSF profile This also gives access to the PSF FITS file The different width of the PSF in x and y direction are due to anisoplanatism The x axis is here defined as the axis that is parallel to the line connecting the reference object with the science target in the direction of the reference object i e as seen from the wavefront sensor in NAOS Conversely the off axis Strehl ratio is computed from the estimated PSF on the science object which allows one to estimate the correction provided by NAOS for the target see section 3 3 e The full width at half maximum of the PSF
37. use empty for imaging Camera Name This template is used for imaging standards and is similar to the NACO_img_obs_GenericOffset template see section 6 5 3 with the difference that some DPR keywords in the FITS headers of the images are set to different values allowing pipeline processing and archiving Additionally NDIT is single valued in this template and offsets are in detector coordinates only This template should be used by all users who wish to take calibrations standard stars observation beyond the ones provided by the Calibration Plan Table 42 describes the parameters of this template P2PP label DIT NDIT Readout mode NEXPO per offset position Number of offset positions Table 42 Parameters of NACO_img_cal_StandardStar List of offsets in X List of offsets in Y Return to Origin T F Filter Neutral density filter Wire grid Camera Default NODEFAULT NODEFAULT Double_RdRstRd 1 NODEFAULT NODEFAULT NODEFAULT T NODEFAULT Full empty NODEFAULT Description Detector Integration Time secs Number of DITs Readout mode Number of exposures per offset position Number of offset positions Offset in arcseconds Offset in arcseconds Return to origin at the end of the template Filter Name Neutral density filter Wire grid use empty for imaging Camera Name 68 NAOS CONICA User Manual VLEMAN ESO 14200 2761 6 6 SDI 6 6 1 Introduction The simultaneous differential imager SDI and
38. used with any narrow to broad band filters in the K band and respectively for the 4QPM designed for the H band 20 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Figure 10 Radial profiles of the PSF compared to that of the coronagraphic image obtained with the 4QPM K left and the 4QPM_H right 13 full undersszed stop ormoalized he y gp yn pe i epg Bb e y A _ pur lt a A gt a p gt o a gt If q 1 Jj i MAS AAA AA UA A A A E 2 00 0 10 9 20 0 30 0 40 Angular separation ri arcsec Figure 11 Chromaticity of the 4QPM_K measured on the 2004 mask with a fiber i e no seeing effects NAOS CONICA User Manual VLEMAN ESO 14200 2761 21 VEA i Ex LA a Ae i J Lyat vs 4QPA I i 4 orf Fm F 4 Pull rara lied of 1 J i 4 L E 4 4 AP a 1 hs Lyot d 0 7 T i C j J i 1 i T 4 ri 4 j Sd a J E 4 ail E el 1 i_ F i f j E H 4 T E i AA A f AAN 4 ELA a lg t 7 i T i J 4 4 I ii t 4 iT a Se KR a A AE ae el 0 0 AF 0LA 0 6 0 8 Argular distance in arcsecend Figure 12 Radial profile for the PSF the 4QPM and the 0 7 Lyot obtained with a natural star in 2004 4 3 4 Comparison with the classic Lyot masks Measurements were made in 2004 and are still valid for the new masks Figure 12 shows data obtained on a natural star The maximum attenuation is only a factor 10 with the 4QPM while it r
39. www eso org instruments naco inst corono html Table 8 Diameter in arcsec of the coronagraphic masks Opaque and held in place with wires 100 extinction over the mask Opaque and held in place with wires 100 extinction over the mask C_0 7_sep_10 0 7 Semi transparent 3 5 x 1073 transmissivity situated on a glass plate Four quadrant phase mask for K band 13x13 FOV Four quadrant phase mask for H band 8x8 FOV In addition to the Lyot style masks there are two four quadrant phase masks 4QPM which reduce the intensity of a source by adding a phase shift of x to the wavefront Unlike the classical Lyot masks a phase mask coronagraph split the focal plane into four equal areas two of which are phase shifted by m As a consequence a destructive interference occurs in the relayed pupil and the on axis starlight rejected outside the geometric pupil is filtered with a diaphragm a Lyot stop of 0 15 diameter The advantage over a classical Lyot mask is twofold there is no large opaque area at the center enabling observations of objects that are within 0 35 of the main source and a larger achievable contrast is met cfr Boccaletti et al The four quadrant phase mask coronagraph PASP 116 p 1061 2004 There are two such masks available Fig 8 e 4QPM_H optimized for a wavelength of 1 60 um circular field of view 8 diameter e 4QPM_K optimized for a wavelength of 2 18 um circular field of view 1
40. 0 8 0 Transmission for 0 ES 0 2 0 0 1 1 1 1 pa o e vw e ES n o e N o 0 8 0 6 Transmission 0 4 0 2 o o E gt m P e o 2 0 2 2 2 4 2 6 2 8 0 8 0 6 y Transmission 0 4 0 2 E ETI 0 0 i 1 3 2 3 4 w o w O w A o Blii o TT ETEA g 0 6 Transmission 0 a 0 2 0 0 f Lasa 1 L 4 0 4 2 4 4 4 6 4 8 5 0 Wavelength um Figure 2 Model atmospheric transmission between 1 and 5 um for a water vapour column density of 1 6mm and at airmass 1 Lord 1992 NASA Tech Mem 103957 NAOS CONICA User Manual VLT MAN ESO 14200 2761 7 has to work harder and the residuals on the two sides of the nod are generally different Consequently they cannot be be perfectly removed For observations with NAOS CONICA it is not necessary to use chopping and nodding for LW imaging spectroscopic and polarimetric observations if the central wavelength of the filter is less than 4 2um the sky is sampled frequently i e more than once per minute and if conditions are clear But for coronographic obser vations where one cannot jitter and for filt
41. 26 NAOS CONICA User Manual VLEMAN ESO 14200 2761 only SDI data of the star and subtracting the SDI star data to themselves but with different angular separations For example we calculate the images that have a separation of 25 SDI 0 SDI 25 and SDI 5 SDI 30 and SDI 10 SDI 35 ete up to SDI 25 SDI 50 Adding them after having rotated them of the right amount will add up the information of the companion However we have only added 6 times the information of the companion while we have a total of 11 images and subtracted out 6 images To add up the other 5 images we can for example subtract to the 5 images that have not been added yet SDI 30 to SDI 50 note that they were used for subtraction though the images that show an angle difference of 25 SDI 50 SDI 25 SDI 45 SDI 20 etc to SDI 30 SDI S Adding all these roll subtracted images corrected from the instrument angle will create a typical spatial structure made of a positive PSF at the companion position and 2 negative PSF located at 25 on each side of the companion The profile in Figure 15 clearly shows an improvement of about 1 mag with respect to standard SDI data reduction SDI 2 rolls Obviously for a companion located at close angular separation the PSFs may overlap and subtract themselves In our case a simple simulation using the real PSF image has been used to estimate the attenuation of the positive PSF For an ang
42. 3 diameter These devices work best for filters that are centered at or near this wavelength NAOS CONICA User Manual VLEMAN ESO 14200 2761 19 par separoten im A U ANQUIOT SEpercuan in A 4 LE Der nena aii SOAS ol hat as Lpprrrrrrrrrry OPT ET TTT TEEN ETS V ET EPSP ETT T eT TET f 4OPM in H 4 f 4 402M in H Lyot 0 15 J o doto gt q es 1 0 ost 3 osp il osf gt 0 6F 4 j Coronogroph oltenuction t 0 4 j 0 4 f f EE 0 02h o 0 2 LJ ES ced PA leo gt ALT E AAA A Lisa ad ocoMiktt i ral 0 0 0 1 0 2 0 5 5 i 7 L3 Angulor distance in orcsecc ds Angular atonce m orcsec Figure 9 Radial attenuation of an off axis point source moved outwards of the mask centre in H left and Ks right The data are shown as symbols and the lines are from simulations Error bars correspond to the uncertainty in the intensity normalization with respect to the simulations 4 3 1 Radial attenuation The intensity of off centered sources is also partially reduced The radial attenuation was measured to evaluate the impact of the Lyot spot on the Inner Working Angle and hence on the attenuation of an off axis point source Measurements were made for both masks and are presented in Figure 9 these plots are important to correct the photometry of off axis objects when looking at close companions for instance For instance a companion lying at 0 1 has its flux absorbed
43. 4 NACO_img acqMoveToSlit This template does a telescope preset and is followed by interactive centering of the object in the slit It is very similar to the NACO_img_acq MoveToPixel template however it must be followed by a spectroscopic template After the AO reference has been acquired the slit is placed into the beam and an image is recorded The slit position is computed the slit is removed and a drawing of the slit is superimposed on the image of the field The centering of the target is then done interactively The template also allows one to place two objects into the slit without the requirement of calculating the position angle beforehand In such cases the acquisition strategy should be adequately explained in the README file and those targets which should be placed in the slit should be clearly designated on the Finding Chart and their position on the slit clearly indicated To save time during the acquisition we recommend that users enter an estimate of the position angle into the acquisition template Table 35 describes the parameters of this template Table 35 Parameters of NACO_img_acq MoveToSlit P2PP label Default Description DIT NODEFAULT Detector Integration Time secs NDIT NODEFAULT Number of DITs PSF reference T F F PSF reference T F Alpha offset from Ref Star 0 Offset from Ref Star arcsec Delta offset from Ref Star 0 Offset from Ref Star arcsec RA offset arcsec 5 RA offset for fixed patte
44. Acquisition 0 75 minutes Initial Setup 2 minutes AO acquisition 5 minutes Imaging acquisition 0 5 minutes Sub total 11 25 minutes Observation 20 1 3 60 27 35 minutes Total 46 minutes Overheads 130 Observation Integration time minutes x 1 30 x 60 seconds Offset overhead Table 30 Overheads Example 9 Imaging a faint source with the FP Template parameters Acquisition Template NACO_img_acq MoveToPixel Observation Template NACO_fpi_obs_GenericOffset DIT 60 seconds NDIT 1 Number of offset positions 10 NEXPO per offset position 1 Readout mode FowlerNsamp Wavelength list 5 settings Execution time Preset 3 minutes Guide Star Acquisition 0 75 minutes Initial Setup 2 minutes AO acquisition 10 minutes Imaging acquisition 0 5 minutes Sub total Acquisition 16 25 minutes Observation 10 13 5 60 2 10 16 75 5 minutes Total 92 minutes Overheads 84 Observation Number of offset positions x Offset overhead Number of FP settings x NDIT x DIT readout overhead FPI setup time between frames without offsets NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 31 Overheads Example 10 A bright source with SDI Template parameters Acquisition Template Observation Template DIT NDIT Number of offset positions NEXPO per offset position Readout mode List of Position Angle Offsets Return to the Original Rotator Position Execution time Preset Guide Star Acquisiti
45. Box Width DEC Offset Object Positions RA Offset Figure 26 An illustration of how the NACO_coro_obs_Stare template works The dashed line connecting position 10 with 1 is the offset done at the end of the telescope since Return to Origin T F is set to T The rather erratic bold lines are wires which hold the coronagraphic mask in place The AO loop is off when the sky is observed large filled in circles and on when the object is observed small filled in circles In this example the parameter settings were Number of AB cycles 2 Number of Exposures Object Only 2 Number of offset positions Sky only 3 Jitter Box Width 9 Sky offset in Dec 15 Sky offset in RA 35 Return to Origin T F T Camera S13 The total integration time excluding overheads is defined in seconds by DIT x NDIT for the OBJECT positions Number of Exposures Object Only NDIT for the SKY positions x Number of offset positions Sky only Number of AB cycles If Number of offset positions Sky only is set to zero the sky is not observed In this case the total integration time is DIT x NDIT for the OBJECT positions Number of Exposures Object Only and all other parameters are ignored In this way the template takes a series of exposures of the target without offsets However sky subtraction is almost always required so this option will probably only be used in very special circumstanc
46. DIT DM ESO ETC FLI FOV FP FS FW FWHM GUI HWP IB IR IRACE LN2 LW NAOS NB ND NDIT NGS OB P2PP PS PSO PSF RON RTC SDI SDI SDI 4 SM SR SW TTM VLT VM WF WFS Four Quadrant Phase Mask Four Quadrant Phase Mask optimized for H band Four Quadrant Phase Mask optimized for K band Adaptive Optics High Resolution IR Camera and Spectrometer Data PRoduct Detector Integration Time Deformable Mirror European Southern Observatory Exposure Time Calculator Fractional Lunar Illumination Field of View Fabry Perot Field Selector Full Well Full Width at Half Maximum Graphical User Interface Half Wave Plate Intermediate Band Infra red Infra red Array Control Electronics Liquid Nitrogen Long Wavelength Secondary Mirror Nasmyth Adaptive Optics System Narrow Band Neutral Density Number of Detector Integration Time Natural Guide Source Observation Block Phase 2 Proposal Preparation Preparation Software Paranal Science Operations Point Spread Function Read Out Noise Real Time Computer Simultaneous Differential Imager Simultaneous Differential Imager larger FoV Coronagraphy with 4QPM and Simultaneous Differential Imager Service Mode Strehl Ratio Short Wavelength Tip Tilt Mirror Very Large Telescope Visitor Mode Wavefront Wavefront Sensor NAOS CONICA User Manual VLT MAN ESO 14200 2761 1 1 Introduction The Nasmyth Adaptive Optics System NAOS and the High Resolution
47. D_Short for the acquisition of very bright targets The star is first acquired in a suitable position 2 away from the center of the 4QPM and an image is recorded to serve as out of mask PSF for photometric reference Then the following steps are performed e rough offset to position the star behind the mask e removal of the ND_Short filter adapt DIT if needed fine centring e record the final acquisition image Table 37 describes the parameters of this template Table 37 Parameters of NACO_img_acq_SDIMoveToMask P2PP label Default Description DIT NODEFAULT Detector Integration Time secs NDIT NODEFAULT Number of DITs PSF reference T F F PSF reference T F RA offset arcsec 5 RA offset for fixed pattern arcsec DEC offset arcsec 5 DEC offset for fixed pattern arcsec Position Angle on Sky 0 Position angle in degrees Add Velocity Alpha 0 Additional tracking vel in RA Add Velocity Delta 0 Additional tracking vel in DEC Filter NODEFAULT Filter Name H or empty Neutral density filter Full_Uszd Full_Uszd mask or Neutral density filter Type of AO Observation LGS NGS NODEFAULT LGS or NGS observation type NAOS parameter file NODEFAULT NAOS parameter file 1 In arcsec sec 6 4 7 NACO_img_acq Polarimetry This template does a telescope preset and is followed by interactive centering of the object It is very similar to the NACO_img_acq MoveToPixel template however it must be followed by a polarimetric template
48. FAULT Declination offset in arcseconds Sky offset in RA NODEFAULT RA offset in arcseconds Filter NODEFAULT Filter Name H or empty The template provides the flexibility to adjust the number of NDIT sub integrations for the OBJECT and SKY frames NDIT for the OBJECT positions defines the number of sub integrations on the object and NDIT for the SKY positions defines the number of sub integrations on the sky NAOS CONICA User Manual VLEMAN ESO 14200 2761 85 The total integration time excluding overheads is defined in seconds by DIT x NDIT for the OBJECT positions Number of Exposures Object Only NDIT for the SKY positions x Number of offset positions Sky only Number of AB cycles If Number of offset positions Sky only is set to zero the sky is not observed In this case the total integration time is DIT x NDIT for the OBJECT positions Number of Exposures Object Only and all other parameters are ignored In this way the template takes a series of exposures of the target without offsets However sky subtraction is almost always required so this option will probably only be used in very special circumstances Note that an additional overhead of 2 minutes for target re centring has to be considered everytime that Number of Exposures Object Only is greater than 1 86 NAOS CONICA User Manual VLEMAN ESO 14200 2761 7 acknowledgements We would like to express our deep thanks to W Brandner and C Moutou for th
49. FOV will slightly change when moving from either coronagraphy or spectroscopy to imaging because different flexure compensation models are used for these modes e Some targets we are asked to observe saturate the detector with the minimum DIT Consult the ETC e The pixel scale is very small so the readout noise can dominate if the DIT is too small Consult the ETC e In the NACO_spec_obs_AutoNodOnS1lit template the jitter width should be smaller than the throw 52 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 32 NACO templates cookbook Action Template s to use Acquisition Turn the field telescope rotator Preset telescope and acquire for imaging Preset telescope and acquire for SDI Preset telescope and acquire for polarimetry Preset telescope and center object s in the slit spectroscopy Preset telescope and center object behind the mask coronagraphy Preset telescope and center object behind the mask in SDI 4 NACO_all_obs Rotate NACO_img_acq MoveToPixel NACO_img_acq_SDIMoveToPixel NACO_img_acq Polarimetry NACO_img_acq MoveToSlit NACO_img_acq MoveToMask NACO_img_acq SDIMoveToMask General to all observing templates Make a rotator offset NACO_all_obs_Rotate Imaging or Wire Grid Polarimetry Imaging of uncrowded fields Imaging of extended objects or crowded fields Imaging requiring special offset sequences Imaging with SDI NACO_img_obs_AutoJitter NACO_img_obs_GenericOffset o
50. H K 90 L M 90 thermal IR observations feces 0 80 2 55 um 2 8 5 5 um with WF sensing in the near IR K K 90 V R I J H 90 J H observations The N90C10 dichroic can also be used with the visible WES In this case it acts as a neutral density filter A dichroic splits the light between CONICA and the WES channel Each dichroic is associated with one WES with the exception of the N90C10 For example the visual dichroic can only be used with the visual WFS and the other dichroics can only be used with the IR WES The conditions under which the dichroics can be used are listed in Tab 2 Users are invited to study this table carefully NAOS CONICA User Manual VLEMAN ESO 14200 2761 9 A field selector FS is placed just after the WFS input focus in order to select the reference object for WF sensing The ES also allows object tracking precalibrated flexure compensation and counter chopping It is made up of two parallel tip tilt mirrors working in closed loop to achieve a very high angular stability Two WF sensors are implemented in NAOS one operating in the visible and one in the near IR An off axis natural guide star NGS can be selected anywhere within a 110 arcsecond diameter field of view FOV facilitating a target to reference distance of up to 55 arcsec NAOS allows WF sensing with faint NGS and extended objects but with lower performance The observation of very bright objects is possible with the visible WFS by using n
51. H_SD 4QPM_H_SDI gt gt SDI Sol E x AR j 1073 V RA i e i e Normolized intens Norm y y NO Aa gt ee roket he y s 4 107p y E SIA ES r gt TO Lisisgisad salissa saalis 10 Lansat ml La Lisisa 0 0 D 1 0 2 0 3 0 4 0 5 0 0 0 1 0 2 0 3 0 4 0 5 Angular distance in arcsec Angular distance in orcsec Figure 14 Radial profiles for the PSF solid the 4QPM image dotted and the SDI processing for PSFs dash dotted and 4QPM images dashed Colors are for Ag Az red Ag 43 green 21 Az blue 11 43 purple Left plot is for SDI and right plot is for SDI Images are numbered from 0 to 3 starting from the lower left corner and turning anticlockwise with Ag 41 1 625um Az 1 575um and Az 1 600um We computed Ag 42 Ap 43 41 42 41 43 Normalization to total intensity The results are displayed in Figure The dotted line corresponding to the 4QPM alone is identical to Figure 10 except near the centre because the bandwidth is much smaller than previously and therefore the spectral leakage at the centre is smaller with SDI There is a clear improvement of almost a factor of 10 to use a 4QPM with SDI at high Strehl regime In addition to the fact that the signal to noise ratio is improved since deeper integration time are possible the use of a coronagraph is known to be theoretically more favourable to differential imaging as demonstrated here 4 4 2 Tests
52. Near IR Camera CONICA are installed at the Nasmyth B focus of UT4 NAOS CONICA provides multimode adaptive optics corrected observations in the range 1 5um NAOS Sec 3 is an Adaptive Optics AO system section 2 1 that is designed to work with natural guide stars and extended objects Provisions have been made for it to work with a laser guide star CONICA Sec 4 is an Infra Red IR 1 5 um imager and spectrograph which is fed by NAOS It is capable of imaging long slit spectroscopy coronographic and polarimetric observations with several different plate scales The offered modes for period 79 are listed in Tab 1 NAOS CONICA can be used in Service SM or Visitor Mode VM A number of calibrations are regularly performed by ESO for general use via the NAOS CONICA Calibration Plan Pipelines for quick look data reduction are available for some modes of the instrument Table 1 Main modes and parameters of NAOS CONICA Adaptive Optics 40 Strehl ratio in K under median atmospheric conditions and with a reference object of V 10 mag or K 6 mag Imaging Broad and narrow band filters in the 1 5 0um region with 14 56 fields of view and 13 54 mas pixel scales Simultaneous Differential Imaging SDI VM only Coronagraphy occulting masks of various diameters 4 quadrant phase masks 4QPM_H 4QPM_K VM only Simultaneous Differential Imaging plus Coronagraphy SDI amp 4QPM H VM only Spectroscopy long slit and sl
53. ONICA User Manual VLEMAN ESO 14200 2761 3 NAOS 3 1 Overview NAOS provides a turbulence compensated f 15 beam and a 2 arcmin FOV to CONICA Two off axis parabolas reimage the telescope pupil on the deformable mirror and the Nasmyth focal plane on the entrance focal plane of CONICA A schematic sketch of the optical train of NAOS common path is shown in Figure 3 The optical trains of the wavefront sensors are not shown in this figure CONICA Input Focus Deformable mirror y Dichroic f neci z Output Parabola Input Tip tilt WFS Input Focus mirror VLT Nasmyth Focus Figure 3 A view of the NAOS optical train The tip tilt plane mirror TTM compensates for the overall WF tip and tilt which are the largest distur bances generated by the turbulence The DM which contains 185 actuators compensates for the higher order aberrations including the static aberrations of NAOS and CONICA Table 2 NAOS dichroics beamsplitters Dichroic Reflected light Efficiency Transmitted light Efficiency Conditions VIS V R I 90 J H K L M 90 near IR observations NE 0 45 0 95 um 1 05 5 0 um with optical WF sensing N20C80 V R LJ H K 20 V R I J H K 80 WF sensing and observing 0 45 2 55 um 0 45 2 55 um in the infrared N90C 10 V R LJ H K 90 V R I J H K 10 WF sensing and observing JHK LJ
54. PP Moreover a new prism with the capability of taking spectra over the 1 5 micron range was inserted into the grism wheel Three new spectroscopic modes with the new prism See Table 11 have been defined The spectral resolution varies from about 40 in the J band to 250 in the M band The L27_P1 mode is difficult to use The resolution in J is very low and the background in M is high although it is not so high that normal readout modes cannot be used For targets with blue colours it will be difficult to get good S N at 5 microns without saturating the spectra at 1 micron 4 5 3 Calibration plan For spectroscopic observations a variety of calibration frames will be taken archived and updated at regular intervals The what when and how of calibrations is described in detail in the NACO Calibration Plan http www eso org instruments naos index html Documentation e Telluric Standard Stars Observations of telluric standards will be performed whenever the grisms are used Whenever possible we will limit the airmass difference between the standard and science target to 0 1 airmasses The standard will be observed with the setup that was used for the science target The stars are generally chosen from the Hipparcos catalog and are either hot stars spectral type B9 or earlier or solar type stars spectral types GOV to G4V These calibrations are taken so that telluric features can be removed from science spectra At this point in time
55. Pipeline The NACO_img_obs_AutoJitter NACO_img_obs_AutoJitterOffset and NACO_img_obs FixedSkyOffset templates are supported by the pipeline The NACO_img_obs_GenericOffset is only partly supported Se quences of observations with offsets larger than the field of view mosaicking are not reduced by the pipeline The pipeline also calculates zero points and Strehl ratios for data taken with the NACO_img_cal_StandardStar template read out noise from detector darks and it creates master twilight flats master lamp flats and master dark frames 4 1 5 Fabry Perot Imager In period 81 the Fabry Perot imager is not offered 4 2 Simultaneous Differential Imager The SDI mode of CONICA obtains four images through three narrow band filters simultaneously Two images are taken outside the 1 6um methane feature at 1 575 um and 1 600 um and two images are taken inside the feature both at 1 625 um All filters have a FWHM of 25nm The platescale of the SDI camera is 17 32 mas pixel There are now two SDI modes based on the same principle but with slight differences In the classical SDI mode the beam splitting is done by a double calcite Wollaston The second Wollaston is rotated by 45 deg relative to the first resulting in a rhomboid distribution of the four sub images on the detector See the NAOS CONICA web pages for an example To avoid overlapping of the FOVs a small 5x5 arcsec mask is placed into the entrance focal plane Particular ca
56. Recommended Magnitude Ranges for Standard Stars o e 39 5 15 Maximum Brightness of Observable Targets o o 000004 40 5 16 Night time calibrations ee 40 DALT Pipelines ias ed A id Angas Roe A TA eee We alee Se 41 5 18 Instrument and Telescope Overheads 2 2 2 0 002 eee ee 41 5 19 Observing with the LGS eee 41 NAOS CONICA templates 51 Ged Templates vit a a oa O 51 6 2 General remarks and reminders 0 0 2 pee 51 6 2 1 NACO_all_Obs _Rotate e 53 6 3 Offset conventions and definitions e 53 6 4 Acquisition Templates ee 55 6AL A neta ohh hte a kB ae eet eth Wee Biche de wt Ne eae 55 6 4 2 NACO_img_acqMoveToPixel ee a 55 6 4 3 NACO_img_acq_SDIMoveToPixel o 56 6 4 4 NACO_img_acqMoveToSlit 0 0 0 00 a 57 6 4 5 NACO_img_acqMoveToMask 2 0 0 a ee 58 6 4 6 NACO_img_acq_SDIMoveToMask 0 00 00 pee eee ee es 59 6 4 7 NACO_img_acq Polarimetry 0 0 0 eee eee 59 6 5 Imaging and Wire Grid Polarimetry 0 002 002 eee ee ee eee 61 60 4 Introduction sarra o oe BAe ee BM ae as Se ee es od 61 NAOS CONICA User Manual VLT MAN ESO 14200 2761 vii 6 5 2 NACO_1img ObS _AUtOJitter ee 61 6 5 3 NACO_img_ObsS GenericOt set 0 0 0 0 eee es 62 6 5 4 NACO_img_obs_FixedSkyOffset 2 0 0 00 eee es 63 6 5 5 NACO_img_cal_StandardStar 0
57. S directly This will allow users to use the N90C10 dichroic as neutral density filter for CONICA when using the visual WFS Additionally we have updated some parameters to better reflect the average conditions of the atmosphere above Paranal B 1 Starting up the PS The NAOS Preparation Software can be downloaded for a number of computer platforms at the following URL http www eso org observing etc naosps doc After installation a link to the general server situated at ESO will be required i e the local computer has to have access to the Internet In principle JNPS will work within any Java Virtual Machine which supports Java Development Kit JDK 1 4 0 or later It has been reported to work using a variety of Unix and Linux flavors as well as MacOs X Until further notice ESO will only officially support JNPS under RedHat 9 The PS client is started by typing the command jnps After initialization the main GUI will appear The start up procedure partly depends on the contents of your preferences file which is created in your home directory when you start the PS for the first time This file called jnpscf contains the user s choices for several items some of which can be accessed via the Preferences menu of the main GUI section B 12 B 2 Graphical User Interface Overview The GUI that appears after the initialization phase is depicted in Figure 30 The panel is divided into three areas which are from top to bottom e
58. SDI 4 corrected from detector flat field taken with the H filter only not SDI filters The FoV is 8 for each quadrant The SDI mode of CONICA can be combined with the 4 quadrants phase mask optimized for the H band to achieve high contrast and improve the detectability of faint substellar companions near bright stars ideally down to massive EGPs by reducing the photon noise at small angular separations The advantages of this new mode are e it allows deeper integration by about a factor 50 100 with respect to conventional imaging with SDI unsaturated e it allows to get closer to the central star An example flat field is shown in Figure 13 This mode is now completely commissioned and is offered in VM only as of P81 Please refer to the webpage http www eso org instruments naco inst sdi 4 html for additional information 4 4 1 Contrast with SDI 4 The contrast when combining the 4QPM_H with SDI and SDI was measured The measurements were done as follows Gaussian fitting was used to determine accurately the position of the PSFs in order to measure the relative positions between the 4 images These images were extracted and re centered at the sub pixels precision using the result of the Gaussian fitting Sub images were oversampled to improve alignment if needed and to allow better spectral rescaling 24 NAOS CONICA User Manual VLEMAN ESO 14200 2761 PSF 4QPM_H alized intensity a 8 A PSF y 4QPM_H 4QPM_
59. StandardStar templates this means that the nod throw should be less than 10 arc seconds 6 7 2 NACO_spec_obs_AutoNodO0nSlit This template nods the telescope between two positions A and B along the slit A cycle is a pair of AB or BA observations Cycles are repeated on ABBA sequences E g 3 cycles correspond to an ABBAAB sequence 4 cycles correspond to an ABBAABBA sequence etc Table 44 describes the parameters of this template Table 44 Parameters of NACO_spec_obs_AutoNodOnSlit P2PP label Default Description DIT NODEFAULT Detector Integration Time secs NDIT NODEFAULT Number of DITs Readout mode FowlerNsamp Readout mode Jitter Box Width NODEFAULT _ Jitter Box Width Number of AB or BA cycles NODEFAULT One cycle is an object sky pair NEXPO per offset position 1 Number of exposures Nod throw NODEFAULT Nod Throw in arc seconds Return to Origin T F T Return to origin Slit NODEFAULT Name of the slit Spectroscopic Mode NODEFAULT Spectroscopic Mode The mean size of the nod is defined by the Nod throw parameter The first exposure A is taken after offset ting the object along the slit by Noah 2 arcsec The second exposure B is therefore Nodthrow arcsec from the initial position along the slit In addition to nodding random offsets can be added in the middle of a cycle A sequence of 6 cycles with jittering will result in the following sequence A B e B E A e A e B 6 B e6 A e A e B e5 B e5
60. The menu bar giving access to file related operations and other miscellaneous functionalities see fol lowing sections e The main panel divided in four sub areas which respectively deal with the science target the reference object the sky conditions and resulting performance image quality 90 NAOS CONICA User Manual VLEMAN ESO 14200 2761 bd OS Preparation Softv T R 7 7 2 P 77 7 7 Z I File Objects Preferences Target amp Instrument Setup Reference Objects 7 CONICA Filter Ks Observing Wavelength 2 18 microns Status Name Distance Sr 96 T O TestSourceReference 13 47 7 Dichroic FREE Wavefront Sensor FREE E Target Name TestSource Epoch 2000 0 Equinox 2000 0 RA 01 02 03 Prop Mot RA 0 045 arcseciyear DEC 33 22 f Prop Mot DEC 0 67 arcseciyear rSky Conditions Up Down Delete Clear all Duplicate Seeing at zenith 0 8 E Seeing on reference object 0 89 arcsec AA Distance to Target 13 47 arcsec Airmass 1 2 1 r0 on reference object 0 11 m Theta0 on reference object 1 49 arcsec Name TestSourceReference Ra 01 02 04 Prop Mot RA 0 0 arcseciyear DEC 33 22 fo Prop Mot DEC 0 0 aresecjear Resulting Performance EN s z 5 7 _JTracking Table t w Sr on reference object 120 6 L Effective seeing used 0 837 arcsec at 0 5 um Choose File Sr 2 166 on ref object 20 2 Morphology Point like
61. Time Calculator ETC and P2PP use the output from PS to determine feasibility and to prepare observations For phase II preparation the PS must be used The ETC can be accessed via the regular web based interface http www eso org observing etc or via the HTML file produced by PS For the former the ETC uses a grid of pre defined setups the user only specifies the usual parameters For phase I preparation users can use either access route although we strongly recommend the use of the PS for phase I preparation as well For phase II preparation the HTML file produced by PS must be used At the telescope OBs are executed by the instrument operator Both NAOS and CONICA are setup according to the contents of the OB Note that the NAOS configuration might be further optimized at this time in order to provide better performance A Real Time Display is used to view the output of CONICA and to perform acquisitions while the wavefront pupil is also displayed Daytime calibrations are executed the following morning by observatory staff 5 2 Visitor Mode Operations Visitors arrive on Paranal 2 days ahead of their observing run and receive support from Paranal Science Operations PSO Users are requested to read the P2PP and NAOS CONICA User Manuals before arriving During the night users do not have direct interaction with the instrument and the telescope The execution of their program is undertaken by the instrument operator Visitors
62. VERY LARGE TELESCOPE NAOS CONICA User Manual Doc No VLT MAN ESO 14200 2761 Issue 81 1 Date 22 12 2007 N Ageorges C Lidman Prepared cave news iS Pl a Name Date Signature Approved rey sone Oe ee a eee Name Date Signature Released De NE Name Date Signature 11 NAOS CONICA User Manual This page intentionally left almost blank VLEMAN ESO 14200 2761 NAOS CONICA User Manual VLEMAN ESO 14200 2761 111 Change Record corr just aier PAE Comm I and 2 updates Phase 1 P71 updates 1 4 3 Strehl Ratio Measurement 1 4 4 Minor corrections 1 5 0 Phase II P71 updates 1 5 1 Minor Corrections 152 PTZ CP 1 5 3 Maximum DIT Night time calibrations 1 6 0 28 June 2003 1 1 1 2 4 2 4 3 4 5 15 Phase II P72 updates eee gee 1 7 0 01 Dec 2003 1 2 1 2 2 Tabs 5 9 10 Phase II P73 updates MO and 15 4 5 3 6 9 4 01 Mar 2004 1 3 4 1 3 4 2 4 3 FPI SDI and 4QPM added 1 7 7 01 Apr 2004 4 1 3 5 5 6 5 8 5 15 Template desc for FPI and SDI added 5 17 6 4 6 5 1 7 Tab 15 28 29 Fig 17 19 May 2008 all Comecon oF typos l a 0 19 June 2004 4 4 2 Fig 6 new spec modes with SL SHK and prism 4 6 Presentation of NEW CONICA detector 6 2 1 special rotation template added Appendix B New version of PS 23 Nov 2004 1 1 1 3 Update for P75 related to half wave plate 4 5 4 5 1 introduction of the half wave plate 6 2 6 10 4 introduction amp definition of NACO_pol_obs Retarder
63. aforementioned lists Lists do not need to have the same length If the number of exposures is larger than the number of elements in a list the list is restarted from the beginning as many times as needed until the correct number of frames have been acquired The lists can have any length however having lists of different lengths can become extremely confusing It is good practice to use lists of equal length or lists with only one value when one parameter remains constant This template allows slit scanning across an object by defining a list of offsets in the Y direction NACO_spec_obs_GenericOffset 1024 1024 Y Acquisition Position 4 1 Slit Pana o 3 2 E Slit Angle 45 degrees N CONICA FOV S27 28 1 1 X Figure 24 An illustration of how the NACO_spec_obs_GenericOffset template works The AO loop is off when the sky S is observed large filled in circles and on when the object O is observed small filled in circles The dashed line connecting 4 with acquisition position is the offset done at the end of the telescope since the Return to Origin T F was set to T In this example the parameter settings were Number of offset positions 4 NEXPO per offset position 1 Observation Type 0 or S OSSO Offset Coordinates DETECTOR List of offsets in RA or X 70 140 List of offsets in DEC or Y 0 707 Return to Origin T F T If the parameter Return to Origin T F is set to true T the t
64. angle usually 20 at 2um but only 5 in diameter at 0 6um However even for observations at 2 2um the sky coverage achievable by this technique equal to the probability of finding a suitable reference star in the isoplanatic patch around the chosen target is only of the order of 0 5 to 1 The most promising way to overcome the isoplanatic angle limitation is the use of artificial reference stars or laser guide stars LGS Laser Guide Stars are artificial sources potentially replacing Natural Guide Stars NGS as reference objects for Adaptive Optics AO image corrections The rationale is the much higher sky coverage offered in principle by an LGS as opposed to the standard NGS approach Due to the bright m 11 13 artificial star created near the centre of the field the probability to achieve a given minimum AO correction on an arbitrary astronomical target goes e g from a meager 3 with an NGS to 65 with an LGS for corrected images with at least a 20 K band Strehl ratio Nevertheless there are still a number of physical limitations with an LGS The first problem is the focus anisoplanatism also called the cone effect Because the artificial star is created at a relatively low altitude back scattered light collected by the telescope forms a conical beam which does not cross exactly the same turbulence layer areas as the light coming from the distant astronomical source This leads to a phase esti mation error The effect is
65. antum efficiency fo the WES detectors as a function of wavelength B 6 Optimizing NAOS and Getting a Performance Estimation The optimal configuration i e the one giving the highest Strehl and the resulting PSF are determined when the Optimize button located in the bottom left corner of the graphical user interface is selected The typical response time from the server is 10 seconds and should not exceed 60 seconds When more than one reference object has been defined the optimization is done for the selected highlighted one For complete preparation the Optimize command should be repeated for each potentially viable reference object Once you have made a request for optimization and if it has been successfully processed the GUI will be updated with the optimal AO configuration Figure 33 and an estimation of the resulting PSF The Strehl ratio is always computed for the reference object on axis at the observing wavelength and at 2 166 um For the science target off axis the Strehl ratio is given at the observing wavelength only NAOS CONICA User Manual VLEMAN ESO 14200 2761 95 Tracking Table Data Figure 32 An example of tracking table window acquisition and observation of moving objects Offsets in RA and DEC are given in acrseconds Figure 33 Performance subpanel the AO optimal configuration and the PSF is available from buttons in this panel 96 NAOS CONICA User Manual VLT MAN ESO 14200 2761 The optimal Adapti
66. aracteristics of the Aladdin 3 array are summarized in Table 14 Table 14 CONICA detector Detector Format Pixel Size Dark current wavelength range Q E pixels um ADUs pixel um Aladdin 3 1026 x 1024 0 05 0 15 0 8 5 5 0 8 0 9 The dark current consists of the array dark current which is much lower than the numbers listed here and thermal radiation from the instrument 2 Although the array has 1026 rows only the first 1024 are used The last two rows do not contain useful data In most cases users will receive images that have 1024 pixels in x and y For observations in the M band the array is windowed to 512 x 514 The new detector is more sensitive to heavily saturated sources The limiting magnitudes that are observable are specified in Table 19 Please check carefully section 5 15 for tolerated saturated observations For bright objects a number of electronic and optical ghosts become apparent If the source is at pixel coordinates x y there will electronic ghosts at approximately 1024 x y 1024 x 1024 y and x 1024 y and there may be an optical ghost which looks like a set of concentric rings The ghosts can be seen in Fig 16 4 7 2 DIT and NDIT The IRACE controller controls the detector front end electronics and manages pre processing of the data be fore transferring them to the workstation A single integration corresponds to DIT Detector Integration Time seconds The pre processor average
67. arc lines and there might be a possibility of using the very broad telluric features shortward of 4 microns to use this technique over the entire 1 5 micron wavelength range However this remains to be tested NAOS CONICA User Manual VLEMAN ESO 14200 2761 29 CutOff_2 5um 4 1 0 85 2 50 S27_P1 CutOff_2 5um 8 2 0 85 2 50 Based on the 86mas slit and on the central wavelength 2 Fit based on spectra taken were taken with several narrow band filters to create pseudo arc lines The fit is valid from 1 to 4 microns 3 Fit based on telluric absorption features at 5 microns The fit is valid from 4 5 to 5 5 microns 4 Data for the S27_P1 mode has not been taken Planetary nebulae do not appear to be suitable At J the resolution is too low and at M the thermal emission from the nebulae dominates 4 5 4 Night time arcs and flat fields Imperfections in the slits together with instrument flexure means that day time flat fields and arcs depend on the rotator angle For this reason the template NACO_spec_cal_NightCalib allows one to take night time arcs and flat fields immediately after spectra have been taken In general the difference between night and day time calibrations is small and most users will not need to take these calibrations 4 5 5 Pipeline The spectroscopic mode of NAOS CONICA is not supported by the pipeline 4 6 Polarimetry A Wollaston prism and four wire grids are available for imaging polarimetry as well as a turnable
68. are This section describes the Preparation Software PS which is a key tool in the preparation of OBs in both Visitor and Service Mode The purpose of the PS is to find the optimal NAOS configuration for a given set of conditions to compute the associated performance and to provide input to P2PP and the ETC Input to the PS is done through a Graphical User Interface GUI and includes atmospheric conditions such as seeing and airmass target parameters such as the observing wavelength and the dichroic and reference source parameters such as brightness morphology and the distance between reference and target Output consists of a configuration file for P2PP Sec B 8 an estimate of the performance in terms of Strehl a 2 dimensional PSF and an HTML formatted file Sec B 7 for the ETC The ETC can be accessed via the regular web based interface http www eso org observing etc or via the HTML file produced by PS For phase II preparation the HTML file produced by PS must be used Finally in the course of the execution of the observations at the telescope the PS is able to take into account the current external conditions and actual reference instead of expected source characteristics to optimize the observations still respecting the astronomer s requirements for observing wavelength transmission and so on The FITS headers of NAOS CONICA data contain all the necessary information on the setup used Users can select the WF
69. ate provides interactive tools like dragging arrows to define telescope offsets 5 7 2 Spectroscopy It is mandatory to use the NACO_img_acq_MoveToSlit acquisition template for all spectroscopic OBs and the same slit in both the acquisition and observing templates This template provides interactive tools to rotate the field and to center objects into the selected slit which is overlaid on the RTD It can also be used to place two objects in the slit without having to pre compute the position angle Instructions for specifying this acquisition procedure at phase II are in Section 6 4 4 These instructions must be strictly adhered to 5 7 3 Coronagraphy It is mandatory to use the NACO_img_acqMoveToMask acquisition template for all coronographic OBs and the same mask in both the acquisition and observing templates This template provides interactive tools to center objects behind the selected mask which is overlaid on the RTD 5 7 4 SDI 4 It is mandatory to use the NACO_img_acq SDIMoveToMask acquisition template for all SDI 4 OBs and also use the same setup in both the acquisition and observing templates with the possible exception of the ND_Short filter which is used during acquisition of bright stars This template provides interactive tools to center objects behind the 4QPM_H mask 5 7 5 Polarimetry For those OBs which use the Wollaston prism it is mandatory to use the NACO_img_acq Polarimetry acqui sition template and to use the same
70. avefront WF by adaptive optics AO Figure 1 The wavefront sensor WFS measures WF distortions and these measurements are processed by a real time computer RTC The RTC controls a deformable mirror DM and corrects the WF distortions The DM is a continuous thin plate mirror mounted on a set of piezoelectric actuators that push and pull on the back of the mirror Because of the significant reduction in the WF error by AO correction it is possible to record images with exposure times that are significantly longer than the turbulence correlation time This error directly determines the quality of the formed image One of the main parameters characterizing this image quality is the Strehl ratio SR which basically corresponds to the amount of light contained in the diffraction limited core relative to the total flux An AO system is a servo loop system working in closed loop The DM flattens the incoming WF and the WES measures the residual WF error The WFS in NAOS uses a Shack Hartmann screen It consists of a lenslet array that samples the incoming WF in a pupil plane Each lenslet forms an image of the object and the displacement of the image gives an estimate of the WF slope at that lenslet A good feature of this WES is that it works with white light extended sources and very faint stars The performance of an AO system is directly related to the number of lenslets in the lenslet array the number of actuators behind the DM and the rate
71. band filter plus one neutral density filters These limits apply for DIT lt 1 Such bright objects heavily saturate the detector and cannot be used for science For longer DITs these limits should be increased by approximately 1 magnitude for every 10 fold increase in DIT The careful reader will note that this is not a linear relation When acquiring or when observing targets in imaging or polarimetry a saturation of a factor 4 is the maximum acceptable The saturation level is defined for each detector mode by the full well depth see Table 15 Any other expected saturation level for field stars should be accepted prior to observation In service mode walver request must be submitted In visitor mode prior approval for such observation must be seeked espe cially if only half nights are attributed to the project The magnitude at which saturation starts depends on several parameters filters Strehl objective etc The ETC should be used to check that objects of scientific interest do not saturate the detector 5 16 Night time calibrations For spectroscopic observations users can take spectroscopic flats and arcs immediately after the observation These night time calibrations are generally better than the ones taken in the daytime because daytime calibra tions are taken with the rotator in a fixed position and a combination of instrument flexure and inhomogenities along the slit causes the image of the slit on the detector to mo
72. cf file located in the user s home directory Additionally depending on your local installation of the PS you may want to edit the file and modify the web enable resource enabling you to switch between the standard installation web enable true and the case where you access the PS server on your local machine web enable false However this latter case should normally never be encountered by the average user hence the default value is the correct one in most cases
73. ct and adds 1t at the bottom of the list This may prove useful if you want to experiment with a reference object and you want to be able to compare different results of optimization while keeping all of them in the GUI instead of simply overwriting the results B 5 2 Morphology The Preparation Software and the NAOS instrument can also handle moderately extended objects up to 3 arcsec in diameter to analyze the incoming wavefront Several models are available to define the morphology of the reference object Objects with one of three different morphologies can be used as NAOS reference objects e Point like object e Binary object which requires an angular separation between the two components given in the range 0 2 5 in arcseconds and NAOS CONICA User Manual VLEMAN ESO 14200 2761 93 the flux ratio of the two components flux of fainter companion flux of brighter component dimensionless e Disc like object When using a resolved object in the solar system you are asked to enter its diameter in arcseconds This morphology is modeled by a limb darkened disk B 5 3 Photometry The PS also has to compute the flux coming from the reference object Since the WES spectral bandwidths are very large a single magnitude is not sufficient to compute the detected number of photons The photometric information may be provided in different ways e Magnitude Spectral Type Well suited to main sequence stellar objec
74. defining the nod throw users are requested to ensure that other objects in the slit do not cause the spectra to overlap when the throw is executed The total number of frames is Number of AB or BA cycles x NEXPO per offset position x2 The total integration time excluding overheads is defined in seconds by DIT x NDIT x NEXPO per offset position x 2x Number of AB or BA cycles 6 7 3 NACO_spec_obs_GenericOffset This template is used for spectroscopy and has the flexibility of programming any sequence of telescope offsets It is essentially intended for programs requiring large offsets off the slit or slit scanning across one object Table 45 describes the parameters of this template Table 45 Parameters of NACO_spec_obs_GenericOffset P2PP label Default Description DIT NODEFAULT Detector Integration Time secs NDIT NODEFAULT Number of DITs Readout mode FowlerNsamp Readout mode NEXPO per offset position 1 Number of exposures per offset position Number of offset positions NODEFAULT Number of offset positions Observation Type 0 or S NODEFAULT O is with AO S is without Offset Coordinates NODEFAULT SKY or DETECTOR List of offsets in RA or X NODEFAULT Offset in arcseconds List of offsets in DEC or Y NODEFAULT Offset in arcseconds Return to Origin T F T Return to origin at the end of the template Slit NODEFAULT Name of the slit Spectroscopic Mode NODEFAULT Spectroscopic Mode Telescope offsets are defined as l
75. e Wollaston prism and the wire grids so J band polarimetric observations are not possible with NAOS CONICA In this manual filters with central wavelengths longer than 2 5 microns will be referred to as LW filters and filters with wavelengths shorter than 2 5 microns will be referred to as SW filters NAOS CONICA User Manual VLT MAN ESO 14200 2761 TADC CONICA Adapter Calibration Source tp gt Cryogenic Shutter Fabry Perot Pupil Stop Grism Pol Wheel Filter Wheels Camera Mask Wheel Collimator Closed Cycle Cooler Motor Encoder Units __LN2 Cycling Radiation Shield ______ Vacuum Control System Central Valve Turbo Molecular Pump Figure 5 CONICA schematic overview 13 14 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 5 List of available Cameras with plate scales fields of view and wavelength ranges Camera Scale FOV Spectral mas pixel arcsec range L27 27 19 28x 28 2 5 5 0 um L54 54 9 56x56 2 5 5 0 um For imaging with the SDI mode only See Sec 4 2 Not all filter and camera combinations are supported For the S13 S27 and S54 cameras all SW filters can be used For the L27 camera the NB 3 74 NB_4 05 L and M filters can be used For the L54 camera only the NB_3 74 and NB 4 05 filters can be used Observations with the M filter are restricted to a FOV of 14 arcsec x 14 arcsec The FOV is smaller in M
76. e selected with the visible WES in order to reduce the flux transmitted to CONICA for instance with a very bright source In a similar way the wavefront sensor can be selected This is where one can indicate the wish to use the laser guide star LGS Only if the WFS has been selected as LGS will an LGS mode be proposed to the user There are borderline cases when one has to decide whether to select LGS or NGS mode The limiting magni tude is currently 13 5 14 1 e with AO reference stars which are fainter than this limit one should select LGS mode and keep the star as a tip tilt reference Brighter stars offer better performance in NGS mode When NAOS CONICA User Manual VLEMAN ESO 14200 2761 91 using the PS a good rule of thumb is the following if the expected Strehl ratio calculated for the NGS mode 1s 10 or higher stay with NGS Otherwise move to LGS Until further notice no mixed configuration or dual OBs are allowed if the first choice is LGS the second cannot be NGS with VIS WES Moreover only PIs that explicitely requested LGS in Phase I will be granted its use Target information consists of a name coordinates and proper motion For the proper motion to be taken into account it is compulsory to provide both epoch and equinox for which the coordinates are provided The corresponding coordinates at the time of observation does correspond to the precessed coordinates at the mean epoch for a given period i e 2007 0 for P78
77. e supported LW lamp flats are not possible For the LW filters the only alternative is to use a sky frame to flat field the data Table 51 describes the parameters of this template Table 51 Parameters of NACO_coro_cal_NightCalib P2PP label Default Description Number of Night Flats 1 Night time flat field 6 9 5 NACO_coro_cal_StandardStar This template is used to observe standards with the semi transparent coronagraphic mask It is similar to the NACO_img_obs_GenericOffset template see section 6 5 3 with the difference that some DPR keywords in the FITS headers of the images are set to values that allow pipeline processing and archiving Additionally NDIT is single valued in this template and offsets are in detector coordinates only Users should specifiy the offsets with some care as the purpose of this template is to allow photomotry with the glass plate that holds the coronagraphic mask Images of the coronagraphic masks are available from the NAOS CONICA web pages This template can also be used to observe photometric standards with the masks that are held by the wires C_0 7 and C_1 4 In this case the masks will not be inserted in the focal plane but the correct pupil mask will Table 52 describes the parameters of this template NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 52 Parameters of NACO_coro_cal_StandardStar P2PP label DIT NDIT Readout mode NEXPO per offset position Number of offset positions
78. e the pipeline reduced data for themselves Pipeline reduced data are not part of the data package they receive at the end of their run 5 18 Instrument and Telescope Overheads The execution time report produced by P2PP computes the overheads according to the rules reported in Ta ble 20 Users especially those in service mode should check them and make sure to take them into account for their Phase 1 amp 2 proposal Note that any LGS acquisition will last 10 minutes longer than the corresponding NGS acquisition i e 22 minutes for a polarimetric acquisition using the LGSF Some examples Tables 21 to 31 are given below to illustrate how to compute overheads with NACO In all examples we have assumed that the reference source used for AO and the target are the same Not all parameters of the listed templates are shown Only those that have an impact on the overheads are listed 5 19 Observing with the LGS At the time of updating this manual the LGS mode of NAOS is still poorly characterised Its use is for the time being recommended only for science programs which can take advantage of moderate Strehl ratios seeing enhancements to achieve their scientific goals From the past commissionning experience one advises to avoid LGS observations for objects below airmass 1 5 for which the AO correction degrades strongly Due to the tip tilt indetermination see Section 3 4 a natural guide star NGS is still required to correct f
79. eaches typically 200 with the 0 7 Lyot therefore allowing deeper integrations However the Lyot mask is blind over an area 4 times larger than the 4QPM near the centre and thats precisely the interest of the 4QPM 4 3 5 Observations strategy with 4QPMs The precise centering of the science target behind the focal plane mask is critical for the success of the coronagraphic observations and it is done interactively through an acquisition template It can also be tuned during the execution of the observing templates In general the mask centers do not coincide with the center of the chip and the field of view can be vignetted in complex ways Both the center and the amount of vignetting depend on the mask and the objective Coronagraphic images with 4QPM and broad band filters provide a marginal improvement of contrast at a given radius although a significant maximum attenuation 20 200 depending on coronagraphs enable large signal to noise ratio with no need of saturation A large fraction of the flux is therefore left in the focal plane composed with a dynamical halo averaging over time and fluctuating too plus a quasi static halo 22 NAOS CONICA User Manual VLEMAN ESO 14200 2761 corresponding optical aberrations along the optical train from telescope to detector It is recommended here to observe a reference star to calibrate these 2 halos The reference star is chosen with same visible and IR magnitudes to ensure similar AO correction and
80. ectroscopy or SW NB imaging The minimum DIT is 1 7927 seconds The detector mode refers to the setting of the array bias voltage and four modes have been defined HighSensitivity HighDynamic HighWellDepth and HighBackground The well depth and the number of hot pixels is di rectly related to the detector mode HighSensitivity has the fewest hot pixels but it has the smallest well depth Conversely HighBackground has the largest well depth but has many more hot pixels The former is used for long integrations in low background situations where cosmetic quality and low readnoise are paramount while the latter is used in high background situations where cosmetic quality is less important The detector mode is not a parameter that users can select It is set automatically and depends on the instrument setup For example all observations in FowlerNsamp will use HighSensitivity Details of how the detector modes are assigned are given in Table 15 The maximum allowed DIT is now unconstrained by the array However in practice the maximum DIT is defined by the need to get sky frames and this will be around 900 seconds Users should be aware that some of the observatory provided calibrations will only be done in one readout mode For example standard star observations in the SW broad band filters will only be done in Double RdRstRd If users want to observe a standard in a mode that is not supported in the calibration plan they should submit th
81. ee a I 11 5 CONICA schematic overview ee 13 6 EONICA SDEFOM jo n ea aa ee gh eed BOS ea Of ae a a Ges a 17 To EONICA SDEPON Lua a hE aa er the so stats e of hak Rea God aoe a gentle 17 8 Famed OFADPMS 36 24 16 Seed aed ac nt A ba ie Se A A A te 18 9 Radial attenuation for4QPM 2 a r a a a e e A aa e 19 10 Contrast 0f 4QPM a s et arer a Tite ike OE OW ee A Mee AAA 20 11 Chromaticity of the 4QPM 2 ee 20 12 Radial profile comparison 21 13 SDH Matilde A A RO ee E ae Pe e 23 14 SDI 4 Contrast plot e 24 15 Coparison of rotation tests plots o o ee 25 16 Ghosts visible on CONICA o o ee 31 17 Orientation for Imaging Polarimetry and Coronagraphy oo o 53 18 Orientation for Spectroscopy scce sae ee 54 19 NACO_img_obs_AutoJitterexample o e eee eee 62 20 NACO_img obs_GenericOffsetexamplel oo o e 64 21 NACO_img_obs_GenericOffsetexample2 2000000000004 65 22 NACO_img_obs_FixedSkyOffsetexample o e eee eee 66 23 NACO_spec_obs_AutoNodOnSlitexample o o 71 24 NACO_spec_obs_GenericOffsetexample o 73 25 NACO _pol_obs_GenericOffsetexample o 2 000000 eee TT 26 NACO_coro_obs_Stare example e 80 27 NACO_coro_O0bs_AStro example a 82 28 gt Broad band filters i ia Arn A Da a AL a A a
82. eference T F F PSF reference T F RA offset arcsec 5 RA offset for fixed pattern arcsec DEC offset arcsec 5 DEC offset for fixed pattern arcsec Position Angle on Sky 0 Position angle in degrees Add Velocity Alpha 0 Additional tracking vel in RA Add Velocity Delta 0 Additional tracking vel in DEC Filter NODEFAULT Filter Name Mask Position NODEFAULT Coronagraphic mask Neutral density filter Full Neutral density filter Camera NODEFAULT Camera Name Type of AO Observation LGS NGS NODEFAULT LGS or NGS observation type NAOS parameter file NODEFAULT NAOS parameter file ln arcsec sec This template records either two or four images If only two images are recorded then the first image is an image of the approximately centered target without the mask and the second image is an image of the target accurately centered behind the mask If four images are recorded then these images become respectively the 3rd and 4th images and the first two are images of the reference and they are used by the operator to help in classifying the OB NAOS CONICA User Manual VLEMAN ESO 14200 2761 59 6 4 6 NACO_img_acq_SDIMoveToMask This template does a telescope preset which is followed by interactive acquisition of the object behind the 4QPM_H in combination with the SDI camera It must be followed by the dedicated SDI 4 template which uses the same instrument setup Exception to this rule is the use of the neutral density filter N
83. eir own OBs See Sec 4 1 3 4 6 1 and 4 3 6 for additional details NAOS CONICA User Manual VLEMAN ESO 14200 2761 33 Table 15 CONICA detector readout modes for each astronomical use the mode Readout Noise RON gain full well FW capacity and minimum DIT min DIT are given HighSensitivity Double_RdRstRd HighDynamic LW NB imaging Uncorr HighDynamic LW L imaging Uncorr HighWellDepth LW M imaging Uncorr HighBackground This refers to the full well depth In this case the array is completely saturated and photometry cannot be done Generally users should keep the peak count to below two thirds of the full well depth 2 For exposures with DITs that are within a factor of a few of the minimum DIT the well depth is reduced by a factor of approximately two because of the readout overhead 3 In M imaging the array is windowed 34 NAOS CONICA User Manual VLEMAN ESO 14200 2761 5 Observing with NAOS CONICA at the VLT 5 1 Overview As with other ESO instruments users prepare their observations with P2PP Acquisitions observations and calibrations are coded via templates Sec 6 and two or more templates make up an Observing Block OB OBs contain all the information necessary for the execution of an observing sequence Specific to NAOS CONICA the Preparation Software PS See Appendix B is a key tool since it allows one to optimize the adaptive optics configuration and to estimate performance Both the Exposure
84. eir subtantial contribution to prior user s manual versions NAOS CONICA User Manual VLEMAN ESO 14200 2761 87 A Filter Transmission Curves A 1 CONICA Broad band imaging and order sorting filters The transmission curves at the J H Ks L M and spectroscopic order sorting filters are displayed in Figure 28 Electronic versions of the transmission curves of all filters including the NB and IB filters are available from the NAOS CONICA web pages Transmission Transmission Wavelength microns Figure 28 Filter curves for J H Ks L and M and the order sorting spectroscopic filters SJ SK L The H and L band filters are also used as order sorting filters in spectroscopy 88 NAOS CONICA User Manual VLT MAN ESO 14200 2761 A 2 CONICA Neutral density filters CONICA is equipped with a short wavelength 1 to 2 5 um and a long wavelength gt 2 5 um neutral density filter The wavelength dependence of the attenuation is shown in Figure 29 Neutral Density Filter 0 025 A S J i __ _ me i weme ros_ _ _ ND2_short ND2_long 0 02 e 0 015 2 on 2 E on c g F 0 01 0 005 0 08 1 12 14 16 18 2 22 24 26 28 3 32 34 36 38 4 42 44 46 48 5 52 54 5 6 58 6 Wavelength um Figure 29 Transmission curves of the neutral density filters in CONICA NAOS CONICA User Manual VLEMAN ESO 14200 2761 89 B Preparation Softw
85. elescope returns to the starting position If not the telescope is not moved The total integration time excluding overheads is defined in seconds by DIT x NDIT x Number of offset positions x NEXPO per offset position 74 NAOS CONICA User Manual VLEMAN ESO 14200 2761 6 7 4 NACO_spec_cal_StandardStar This template is used for spectroscopic standard star observations It is strictly equivalent to the NACO_spec_obs_AutoNodOnS1lit template in the definition of the parameters The user is referred to the description of the NACO_spec_obs_AutoNodOnS1it template for the description of the parameters see section 6 7 2 This template should be used by users who need calibrations beyond the ones provided by the Calibra tion Plan of this mode The differences with NACO_spec_obs_AutoNodOnS1lit are that some DPR keywords in the FITS headers of the images are set to different values allowing pipeline processing and archiving 6 7 5 NACO_spec_cal_NightCalib This template is used for taking night time arcs and flat fields and it should be placed immediately after the spectroscopic templates If Night Arc T F is set to T a pair of exposures one with the arc lamp on and another with the arc lamp off will be taken If set to F no arcs are taken If Number of Night Flats is set n where n can be from 0 to 3 n pairs of exposures are taken Each pair consists of one exposure with the flatfield lamp on and one exposure with the flatfield lamp o
86. ers with wavelengths greater than 4 2 um efficient subtraction of the sky background will require chopping and nodding Since chopping is not offered in P81 these observing modes will not be available 2 2 3 Spectroscopy Spectroscopic observations with an AO system lead to the following effects e An increase in the Strehl ratio along the spectrum with increasing wavelengths Depending on the setting the Strehl ratio can change by 10 e A wavelength shift caused by the change in the Strehl ratio as a function of wavelength In particular at shorter wavelengths the FWHM of the PSF of the science object can be smaller than the slit width which leads to the wavelength shift that depends on the location of the object in the slit e A complex line profile The spectrum is the sum of a diffraction limited core and a halo that is limited by the external seeing This results in a combination of line profiles in the final spectrum the line core is at the highest spectral resolution while the wings have a lower spectral resolution since they are defined by the slit width Calibrating AO corrected IR spectra is therefore more complicated than calibrating IR spectra from an non AO instrument The steps are similar in both cases but the accuracy at which it can be done in AO corrected spectra is likely to be lower It will be harder to remove telluric lines that come from the Earth s Atmosphere and to do spectrophotometric calibration 8 NAOS C
87. es 6 9 3 NACO_coro_obs_Astro This template is used for Coronagraphic observations It runs after a normal coronagraphic acquisition It takes NEXPO_OBJ of a target behind the coronagraphic mask without moving the telescope Then the coronagraphic mask is removed and NOFF IMG 1 are taken NAOS CONICA User Manual VLEMAN ESO 14200 2761 81 The last offset provided in the NOFF_IMG list moves the telescope onto the sky position Generic offset principle There the mask is inserted again and on an auto jitter principle NOFF_SKY images are taken on sky The idea is to get images of the target with and without the coronagraphic mask Since most sources are too bright for simple imaging there exists the possibility to define a different filter set up for the imaging part of the template The number of coronagraphic images to be taken on the source is defined by NEXPO CORO NOFF_CORO defines the number of sky images to be taken with the coronagraphic mask The integration time DIT CORO is forced to be identical for all data taken with the coronagraphic mask but NDIT can be different for images with the target NDIT_Obj and on sky NDIT_Sky The Readout mode can be selected but remains the same throughout all the template For the imaging part of the template where no coronagraphic mask is used DITIMG amp NDIT_IMG can be defined independently of the rest of the template Similarly the number of exposures per position NEXPO_IMG and the
88. es not require a long list of offsets to be defined Table 39 describes the parameters of this template Table 39 Parameters of NACO_img_obs_AutoJitter P2PP label Default Description Observation Category SCIENCE Observation Category DIT NODEFAULT Detector Integration Time secs NDIT NODEFAULT Number of DITs Readout mode Double_RdRstRd Readout mode Jitter Box Width NODEFAULT Jitter Box Width NEXPO per offset position 1 Number of exposures per offset position Number of offset positions NODEFAULT Number of offset positions Return to Origin T F T Return to origin at the end of the template Filter NODEFAULT Filter Name Neutral density filter Full Neutral density filter Wire grid empty Wire grid use empty for imaging Camera NODEFAULT Camera Name The offsets are distributed randomly within a box whose size is defined by the parameter Jitter Box Width in arc seconds with the condition that the distance between any two points in a series of ten values is greater than a system determined minimum This is intentionally done to ensure that the 5 frames before and after any frame are spatially not too close and can be safely used for creating skies without residual objects for sky subtraction The value of the Jitter Box Width parameter corresponds to the full width of the box in which the 62 NAOS CONICA User Manual VLEMAN ESO 14200 2761 NACO_img_obs_AutoJitter 1024 1024 Y E N SS Positio
89. ess and morphology of the reference object the distance between the reference object and target and instrument performance The performance of NAOS is summarised in Tab 4 The preparation software Sec B should be used for more detailed predictions and simulated PSFs 3 3 Anisoplanatism Anisoplanatism is the field dependence of the PSF It corresponds to the angular decorrelation of the wavefront coming from two angularly separated stars This phenomenon affects the quality of the AO correction in the direction of the target when the reference star is not on axis 10 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 4 Summary of NACO Strehl ratios at 2 2 microns for an AO reference star at an airmass of 1 2 Values are listed for the on axis case when the source and the reference are the same and for a source that is 30 away from the reference star The assumed seeing values are 0 8 and 1 2 at Zenith at a wavelength of 0 5 microns These values were derived with the Preparation Software PS and are also used in the CONICA Phase I Exposure Time Calculator to estimate signal to noise ratios V on axis SR SR at 30 on axis SR SR at 30 0 8 0 87 1 2 1 2 Note Seeing of 0 8 or better can be obtained on Paranal 50 of the time while 1 2 or better can be obtained 80 of the time 3 4 Laser Guide Star facility LGSF Adaptive Optics Operations are strongly affected by the size of the isoplanatic
90. eters By definition a rotation of the polarisation plane by 45 degrees does correspond to a rotation of the half wave plate by 22 5 degrees To image the entire field of view while observing with the Wollaston prism the same care must be taken as for observation with the NACO_pol_obs_GenericOffsettemplate see 6 8 2 The total integration time excluding overheads is defined in seconds by DIT x NDIT x NEXPO per offset position x number of half wave plate angle x Number of offset positions The angle of the HWP used is reported in the fits header under INS RETA2 NAME Previously this keyword did not exist The angle at which the HWP was set could be retrieved from INS ADC1 ENC HWP encoder via the following formula HWP_angle HWP_encoder 205 4096 360 modulo 4096 Example angles of 0 amp 22 5 correspond to INS ADC1 ENC 3891 amp 51 respectively This information remains available from the fitsheader 6 8 4 NACO_pol_cal_StandardStar This template should be used to observe polarimetric standards that do not require chopping It is strictly equivalent to the NACO_pol_obs_GenericOffset template with the difference that some DPR keywords in the FITS headers of the images are set to different values allowing pipeline processing and archiving The user is referred to the description of the NACO_pol_obs_GenericOffset template for the description of the parameters see Sec 6 8 2 NAOS CONICA User Manual 6 9 Coronagrap
91. eutral density filters Note that these neutral density filters are distincts from the neutral density filters of CONICA and are not selectable within the NAOS PS software nor within P2PP The two WF sensors are Shack Hartmann sensors For the visible WFS two Shack Hartmann sensors are available a 14x14 lenslet array with 144 valid sub apertures and a 7x7 lenslet array with 36 valid sub apertures For the IR WES three Shack Hartmann sensors are available a 14x14 lenslet array with 144 valid sub apertures and two 7x7 lenslet arrays with 36 valid sub apertures Independent of which Shack Hartmann sensor is used all 185 actuators on the DM are used The FOV the temporal sampling frequency and the pixel scale of the WFS can also be optimized providing a good performance over a large magnitude range Characteristics of both WES are given in Table 3 Table 3 Wavefront sensors characteristics Wavelength range 0 45 1 0 um 0 8 2 5 um 14x14 FOV per lenslet 2 32 arcsec 5 15 arcsec magnitude range broadband 0 12 4 9 7x7 FOV per lenslet 4 64 arcsec 4 8 and 5 15 arcsec magnitude range 12 16 7 9 12 Detector 128x128 EEV CCD 1024x1024 Rockwell Hawaii With the N20C80 dichroic The magnitude ranges with the N90C10 dichroic will be approximately 1 5 magnitudes fainter 3 2 NAOS Performance The level of the AO correction depends on a large number of factors such as seeing the speed of the turbu lance the airmass the brightn
92. ference object and target be in the slit at the same time Additionally the co ordinates of the reference object are the ones that should go into the OB e When using extended objects as AO reference sources make sure that the flux within the specified aperture is correct Users tend to significantly overestimate this flux e The verify button on P2PP checks that individual parameters are within the defined ranges and some additional checking on the global logic of selected OBs e The Strehl seeing and airmass constraints as well as the epoch equinox and RA and DEC and respec tive proper motion fields of P2PP will be automatically filled when the configuration file is loaded Do not edit these fields e There must be one AO configuration file per target The same AO configuration file cannot be used for different targets See Sec B 8 for more details 6 2 1 NACO_all_obs_Rotate The NACO_all_obs_Rotate template rotates the field of view and it has only one parameter the rotator offset angle The angle is in degrees and a positive angle will rotate the adaptor from North to East Hence objects in an image will rotate from North to West The angle is relative hence the position angle of the field at the end of the rotation will be the position angle of the field before the template was run plus the angle in the template The template can only be followed by imaging templates 6 3 Offset conventions and definitions
93. ff If n is set to zero the default no lamp flats are taken Table 46 describes the parameters of this template Table 46 Parameters of NACO_spec_cal_NightCalib P2PP label Default Description Night Arc T F F Night time arc Number of Night Flats 0 Night time flat field NAOS CONICA User Manual VLEMAN ESO 14200 2761 75 6 8 Polarimetric Templates 6 8 1 Introduction These templates are for polarimetric observations with the Wollaston prism For polarimetric observations with the wire grids please refer to Sec 6 5 For SW observations the readout mode of the detector should be set to either Double _RdRstRd or FowlerNsamp For LW observations the readout mode should be set to Uncorr All other combinations will be rejected at the time the OBs are checked For very bright targets see Sec 5 15 a neutral density filter can be inserted into the light path The choices are Full for no neutral density filter ND_Long for a LW neutral density filter and ND_Short for a SW neutral density filter Since the J band filter is in the same wheel as the Wollaston J band polarimetric observations are not feasible 6 8 2 NACO_pol_obs_GenericOffset This template is used for imaging polarimetry It can be used with all filters with the exception of J and M Rotator offset angles can now be entered as a list The angles are relative so a sequence with 0 45 45 45 would rotate the field by 0 45 90 and 135 degrees from the original rotator p
94. g 5 4 The Influence of the Moon Moonlight does not noticeably increase the background in any of the CONICA modes so there is no need to request dark or gray time for this reason However it is recommended not to observe targets closer than 30 to the moon to avoid problems linked to the telescope guiding active optics system The effect is difficult to predict and quantify as it depends on too many parameters Just changing the guide star often solves the problem Visitors are encouraged to carefully check their target positions with respect to the Moon at the time of their scheduled observations Backup targets are recommended whenever possible and users are encouraged to contact ESO in case of severe conflict i e when the distance to the Moon is smaller than 30 Visitors can use the tools that are available in http www eso org observing support html select the link airmass which is under User Support Tools to help determine the distance between targets and the moon for given dates However the moon may affect the quality of the adaptive optics correction if the source used for wavefront sensing is fainter than V 16 In these cases reducing the FLI constraint to approximately 0 7 and increasing the distance to the Moon to approximately 50 degrees is generally adequate Even here it is important not to over specify the constraints as this reduces the chances of the Observing Block being executed For wavefront sensing in t
95. g lists of different lengths can become extremely confusing It is good practice to use lists of equal length or lists with only one value if one parameter is not changed The total number of exposures is given by the number of rotator positions x Number of offset positions x NEXPO per offset position Unlike other templates this template does not have a Return to Origin T F flag This flag refers to the spatial offsets only and the template will do this automatically before rotating the rotator to the new position Table 47 describes the parameters of this template With this scheme it is possible for the user to sample the object and the sky as desired at several rotator positions It is also possible to code the template so that the object and sky is sampled as desired for one angle 76 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 47 Parameters of NACO_pol_obs_GenericOffset P2PP label Default Description DIT NODEFAULT Detector Integration Time secs NDIT NODEFAULT Number of DITs Readout mode Double_RdRstRd Readout mode NEXPO per offset position 1 Number of exposures per offset position Number of offset positions NODEFAULT Number of offset positions Observation Type 0 or S NODEFAULT O is with AO S is without List of offsets in X NODEFAULT Offset in arcseconds List of offsets in Y NODEFAULT Offset in arcseconds Return to the Original Return to original rotator Rotator Position T F F positition at end of the
96. ging the NAOS configuration The time required for PSF reference star observations will be charged to the user For service mode observations we request that all PSF reference OBs are prefixed with the string PSF_and that clear instructions are written in the README file NAOS CONICA User Manual VLEMAN ESO 14200 2761 39 5 12 Recommended DITs and NDITs Unless the object is bright enough to cause saturation See Tab 15 DITs need to be somewhat larger than those used in ISAAC because the NAOS CONICA plate scale is considerably finer and it takes longer for exposures to be sky noise limited However if there are bright objects of scientific interest in the field of view then DITs will have to be much smaller than the ones listed in Tab 16 For DITs larger than 60 seconds users should consider using FowlerNsamp and not Double _RdRstRd With DITs larger than 60 seconds the number of hot pixels in Double_RdRstRd is noticeably larger Table 16 Recommended DIT in seconds and NDIT ranges for NAOS CONICA DIT seconds DITx NDIT seconds J SW NB filters and FP 60 300 120 300 H and Ks 20 120 60 240 LW NB filters 0 175 2 4 40 80 L band 0 175 30 SW spectroscopy 60 900 120 900 LW spectroscopy 0 4 3 0 60 120 For observations that use chopping DIT and NDIT are computed automatically by the templates 5 13 IR backgrounds Backgrounds are a function of the filter and the dichroic They are listed in Tab 17 Table 17 IR back
97. graphic mask has been replaced by a new one still optimised for K band but with a limited field of view of 13x13 e A new 4QPM optimised for H band observations has been installed Its field of view is of 8x8 e A new SDI mode is offered It uses the same camera as the old one still useable but has a different achromatic double Wollaston and has a square field of view of 8x8 instead of 5x5 NAOS CONICA User Manual VLEMAN ESO 14200 2761 3 2 Observing with Adaptive Optics in the Infrared 2 1 Adaptive Optics 2 1 1 Atmospheric turbulence The VLT Very Large Telescope has a diffraction limited resolution of A D 0 057 arcsec at A 2 2um But the resolution is severely limited by atmospheric turbulence to 4 ro 0 7 arcsec where ro is the Fried parameter The Fried parameter is directly linked to the strength of the turbulence and it depends on the wavelength as 46 5 For average observing conditions rg is typically 60cm at 2 2 um The correlation time of the turbulance T is related to rg and the speed at which the turbulent air travels For a windspeed of 10 m s the correlation time is of the order of 60ms at 2 2 um Both To and ro are critical parameters The larger they are the more stable the atmosphere is and the better the performance of NAOS will be 2 1 2 Adaptive Optics A powerful technique in overcoming the degrading effects of atmospheric turbulence is real time compensa tion of the deformation of the w
98. graphic mask is left in the beam for the sky exposures The object positions will be observed with the AO loop closed The sky positions will be observed with the AO loop open Table 49 describes the parameters of this template Table 49 Parameters of NACO_coro_obs_Stare P2PP label DIT Readout mode Jitter Box Width Number of AB cycles NDIT for the OBJECT positions NDIT for the SKY positions Number of Exposures Object Only Number of offset positions Sky only Sky offset in Dec Sky offset in RA Filter Mask Position Camera Default NODEFAULT Double_RdRstRd NODEFAULT NODEFAULT NODEFAULT NODEFAULT NODEFAULT NODEFAULT NODEFAULT NODEFAULT NODEFAULT NODEFAULT NODEFAULT Description Detector Integration Time secs Readout mode Jitter Box Width Sky only Number of AB cycles E g 2 for ABAB Number of DITs at the object position Number of DITs at the sky position Number of exposures on target Number of exposures on sky Declination offset in arcseconds RA offset in arcseconds Filter Name Coronagraphic mask Camera Name The template provides the flexibility to adjust the number of NDIT sub integrations for the OBJECT and SKY frames NDIT for the OBJECT positions defines the number of sub integrations on the object and NDIT for the SKY positions defines the number of sub integrations on the sky 80 NAOS CONICA User Manual VLEMAN ESO 14200 2761 NACO_coro_obs_Stare Jitter
99. grounds The hyphens mark invalid combinations NAOS dichroic CONICA filter vis moco Nocio ark K Users should note that the RON of the array can dominate if DIT is too small 5 14 Recommended Magnitude Ranges for Standard Stars The recommended magnitude range for standard stars in imaging and spectroscopy is given in Table 18 Saturation with the minimum DIT can occur for targets that are about 1 magnitude brighter than the lower limit in these ranges but this limit is very sensitive to the level of correction These magnitude ranges are valid for observations with the visual dichroic Limits are similar for the JHK and K dichroics and respectively 0 2 and 3 magitudes brighter for the N20C80 and N90C10 dichroics For detailed estimates users should use the ETC 40 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 18 Recommended magnitude range of standard stars for observations with the visual dichroic Magnitude Range SW broad band filters SW NB filters FP LW L band LW M band LW NB filters SW spectroscopy LW spectroscopy 5 15 Maximum Brightness of Observable Targets Bright targets leave residual images that can take several minutes to disappear The table below presents the absolute limits acceptable Table 19 Magnitude limits for DIT lt 1 IR Magnitude gt 6 Any gt 4 and lt 6 Any narrow band filter gt 2 and lt 4 Any filter plus one neutral density filter gt 0 and lt 2 Any narrow
100. h the NAOS configuration will be ignored during the acquisition a valid NAOS parameter file is still required By default the PSF reference T F flag is F 6 4 2 NACO_img_ acqMoveToPixel This template does a telescope preset and is followed by interactive centering of the object It should be used when precise positioning of the object is required It must be followed by an imaging template Because the objectives are not aligned with respect to eachother we recommend that the acquisition template and subsequent observing templates use the same objective In visitor mode the interactive part of the template will be executed by the instrument operator under the supervision of the visiting astronomer In service mode it is mandatory that users users provide detailed information for the field centering on their Finding Charts and or in their README file Table 33 describes the parameters of this template In order for faint objects to be clearly seen an image of the sky is acquired in an offset position defined by the RA offset arcsec and DEC offset arcsec parameters This image is then subtracted from all images that are subsequently displayed on the RTD The integration time for these acquisition images is defined by the DIT and NDIT parameters This template records an image of the field after the acquisition has been completed On some occasions two additional Br_y images of the AO reference source which are used by the operator
101. half wave plate The latter is installed in the entrance wheel of CONICA where the calibration mirror is situated Internal calibrations with the half wave plate are thus impossible The Wollaston splits the incoming light into ordinary and extraordinary beams Thus an image taken with the Wollaston prism will contain two images of every object To avoid sources overlapping a special mask con sisting of alternating opaque and transmitting strips is inserted at the focal plane Thus in a single exposure at least half the field will be missing so three exposures with telescope offsets in between are required to image one field See Sec 6 8 2 Sample flat fields with the special polarimetric mask in the focal plane are available from the NACO web pages To measure the Stokes parameters and hence the degree and position angle of polarisation a second set of images with the Wollaston prism rotated by 45 degrees with respect to the first pair are required This can be achieved either by rotating the entire instrument or by taking data with the half wave plate rotated by 22 5 degrees compared to previous data The beam separation for the different cameras are given in Table 12 The wavelength dependence of the beam separation shows that from 1 to 2 5um the Wollaston prism can be used for broad band application without loss of spatial resolution Within the K band for example the 30 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 12 Beam se
102. has to be sampled separately from the object At thermal IR wavelengths gt 3 um the background is considerably higher and more variable In order to avoid saturation the detector at these wavelengths needs to be read very rapidly which in turn leads to poorer detector cosmetics The standard sky subtraction technique is to use chopping and nodding Chopping is achieved by synchronizing the readout of the detector with the secondary mirror of the telescope M2 which alternates chops between two positions If the chopping is fast enough efficient subtraction of the sky can be achieved by subtracting the images taken at the alternate positions The result of a chopped image is therefore a background subtracted image with positive and negative if within the field of view of the detector objects For the NAOS CONICA the typical distance between the two positions the chop throw is 10 arcsec and the chopping frequency is typically around 0 1 Hz Usually it is essential to combine chopping with telescope nodding i e offsetting in the opposite direction of the chop because chopped images usually leave strong residuals on the detector due to the different optical paths through the telescope With AO fed systems there is an added complication The amplitude of the residuals depends on the strength of the turbulence stronger turbulence means that the deformable mirror 6 NAOS CONICA User Manual VLEMAN ESO 14200 2761 o ESA
103. he IR and for reference sources that are brighter than V 16 the values for Lunar Illumination and Moon Angular Distance in the Constraint Sets of your OBs should be 1 0 and 30 respectively 5 5 Telescope control Most interactions with the telescope consist of telescope presets for acquisition telescope offsets during ob servations and M2 chopping for some LW observations Small offsets i e less than one arc minute are usually completed in 10 seconds of time or less It is important to distinguish between the star that is used by the telescope for active optics and the reference object used by NAOS for wavefront sensing The active optics stars are automatically found by the Telescope Control System and users do not have to worry about finding them The reference object used by NAOS for wavefront sensing and specified within the PS is chosen by the astronomer See Appendix B It is quite common to offset the telescope very frequently when observing with NAOS CONICA and since there are two stars that are used to control the system one for active optics and the other for adaptive optics as well as the scientific target users have to pay very special attention to the restrictions imposed by the system There are essentially two kinds of offsets The first is an offset which results in the NAOS AO loop being closed at the end of the offset The second is an offset which results in the NAOS AO loop being opened at the end of the offset
104. he start of observations 6 2 General remarks and reminders e Only parameters specific to NACO are described The description of other parameters can be found in the P2PP User Manual http www eso org observing p2pp e We strongly recommend that you consult the NACO web pages for the latest information e All imaging observations including observations with the Fabry Perot must use the NACO_img_acq MoveToPixel template for acquisition The NACO_img_acq_Preset template has been removed See Sec 5 7 e All polarimetric observations with the wire grids must use the NACO_img_acq MoveToPixel template for acquisition See Sec 5 7 e All polarimetric observations with the Wollaston prisms must use NACO_img_acq Polarimetry for acquisition e All spectroscopic observations must use NACO_img_acq_MoveToS1it for acquisition e All coronagraphic observations must use NACO_img_acq MoveToMask for acquisition e All observations with the SDI and SDI must use NACO_img_acq_SDIMoveToPixel for acquisition e All observations with the SDI 4 must use NACO_img_acq_SDIMoveToMask for acquisition e It is possible to submit a single OB that comprises several observing descriptions for example one can observe a single target with different filters Most mixed mode observations e g coronagraphy with spectroscopy are generally not allowed Direct imaging after any other mode is allowed but users should note that the position of the object in the CONICA
105. hic Templates 6 9 1 Introduction VLT MAN ESO 14200 2761 79 For SW observations the readout mode of the detector should be set to either Double _RdRstRd or to FowlerNsamp 6 9 2 NACO_coro_obs_Stare This template is used for Coronagraphic observations and it moves the telescope alternatively between a fixed object position and a sky position The parameter Number of AB or BA cycles defines the number of times this is done but unlike the NACO_spec_obs_AutoNodOnS1it NACO_img_obs_AutoJitterOffset and NACO_img_obs_FixedSky0Offset templates the sequence is ABABAB and not ABBAAB for the example in which the Number of AB or BA cycles is set to 3 The number of exposures at the object position is defined by the Number of Exposures Object Only parameter The telescope does not offset between these exposures The number of exposures at the sky position is defined by the Number of offset positions Sky only and the telescope can offset between these exposures The sky positions are randomly distributed around a position that is set at a constant distance defined by the parameters SEQ SKYOFFSET DEC and SEQ SKYOFFSET RA from the original telescope position and within a box whose dimensions are set by the parameter Jitter Box Width in arcsec It is strongly recommended especially for very bright sources to select an area so that the main target is out of the field of view for sky measurements to avoid saturation effects The corona
106. how accurately the instrument induced polarisation can be removed from data 4 6 1 Calibration plan For polarimetric observations a variety of calibration frames will be taken archived and updated at regular intervals The what when and how of calibrations is described in detail in the NACO Calibration Plan http www eso org instruments naos index html Documentation e Twilight flats as described in Sec 4 1 3 Twilight flats are done without the polarimetric mask and without the polarizer However in visitor mode twilight flats with the half wave plate can be requested e Lamp flats as described in 4 1 3 For polarimetric observations two sets of flats are taken For obser vations with the Wollaston the first set is without the polarimetric mask and polarizer and the second set is with these elements For polarimetric observations with the wire grids flats with and without the polarizer are taken There are no internal lamp flat calibration taken with the half wave plate e Detector darks in all readout modes and DITs NAOS CONICA User Manual VLEMAN ESO 14200 2761 31 4 6 2 Pipeline Polarimetric observations are not supported by the pipeline 4 7 CONICA Detector 4 7 1 General characteristics The CONICA detector is a Santa Barbara Research Center SBRC InSb Aladdin 3 array It was installed into CONICA during May 2004 and it replaces the Aladdin 2 detector that had been used since the instrument was first offered The main ch
107. i e tens of point sources in 20 square arcsec or moderately extended objects the standard practice is to resort to the jitter technique and all the CONICA imaging templates make use of it The technique basically consists of taking numerous images of the field typically 10 or more with small offsets between the positions The sky is then estimated from all the observations The most critical aspect of jittering is that the size of the offsets should be larger than the spatial extent of the object s one is observing For more crowded fields or extended objects i e covering a large fraction of the array the jittering technique works less well and the sky has to be sampled separately from the object resulting in a loss of observing efficiency which can amount to 50 of the time if the sky has to be sampled as frequently as the object Still all the object positions can be jittered between themselves as well as the sky positions This minimises the effect that poor array cosmetics have on the data In the case of crowded fields where there is no suitable nearby sky field the jittering technique can still give good results as long as the number of offsets is large i e greater than 20 In spectroscopy the classical technique is to observe point sources or moderately extended sources at two or more positions along the slit allowing one to integrate continuously on the object For crowded fields or extended objects the sky
108. interface can be run without knowing the precise coordinates of the target nor the reference object In this case one need only enter the separation between the two But names and coordinates must be supplied if the interface is being used for OB preparation The default morphology of the reference object is point like which does not need any additional input Other morphologies can be specified see section B 5 2 Other buttons that can be seen next to Register Object are e Reset Form this simply erases the form without confirmation e Update Object if you are modifying the characteristics of a reference object which is already recorded in the table this button will automatically turn red reminding you to click this button to record your changes e Cancel cancel any changes to the selected reference Underneath the table is another set of buttons which allows one to manipulate the list of reference objects e Up Down moves the selected object in the list by swapping it with its neighbor The order in which the reference objects are shown will be the one exported to P2PP Sec B 8 and hence the one tried at the telescope Delete this discards all data pertaining to the selected reference object A confirmation dialog is shown to prevent mistakes e Clear all same as above except that all reference objects of the table will be erased e Duplicate makes a copy of all the characteristics of the currently selected reference obje
109. is given in arcseconds both in the main panel and in the pop up window depicted in Figure 35 e Transmission to CONICA is expressed as a fraction of incoming light at the observing wavelength B 7 Exporting to the Exposure Time Calculator When clicking on Export to CONICA ETC at the bottom of the main panel a file browser pops up You can then give the name of an HTML file that will be created by the GUI and saved to your local disk This HTML file contains the PSF profile the CONICA filter and the magnitude and spectral type of the target To call the ETC load this file into your favorite web browser and click on the Call CONICA ETC button at the bottom of the page B 8 Exporting to P2PP All NAOS CONICA acquisition templates Sec 6 4 require a configuration file which is produced by the Export to P2PP button It has the default extension aocfg and it is saved in the directory specified in the Preferences menu under the option set the cache folder This file contains all the information relevant to the setup of NAOS during acquisition of the target When preparing your observations with the PS and P2PP the following points should be noted 98 NAOS CONICA User Manual VLEMAN ESO 14200 2761 The output file is a text file and it should never be manually edited If you do the execution of your OB will be seriously compromised There must be one configuration file per target The same configuration file cannot be used for different ta
110. ists with the List of offsets in RA or X and List of offsets in DEC or Y parameters Telescope offsets are relative defined either along detector lines X and columns Y or RA and DEC and are in arcsec Offsets in X are along the slit offsets in Y are perpendicular to the slit Additionally the observation type can be defined for each image and is entered as a list in the parameter Observation Type O or S O stands for Object and assigns the DPR TYPE header keyword to OB JECT S stands for Sky and assigns the DPR TYPE header keyword to SKY The loop is closed for the former and open for the latter With large combined offsets the guide probe may not be able to follow the same guide star In such a case the guiding system will automatically find another star but not resume guiding A pop up window will instruct the operator to resume guiding If the guide star has changed during an offset the accuracy of the offset will be poorer than it would have been if the same guide star had been used This will only occur when offsetting from object to sky On the return offset the loop will close and the field selector in NAOS will make sure that the object remains centered in the slit even though the guide star has changed NAOS CONICA User Manual VLEMAN ESO 14200 2761 73 The total number of offset positions is defined in the parameter Number of offset positions This number can be different from the number of elements in the
111. itless spectroscopy together with 4 grisms of resolving power 400 1400 Polarimetry Imaging with a Wollaston prism or wire grids This manual is organized as follows A brief summary of AO techniques and IR observations are given Sec 2 NAOS is described in Sec 3 CONICA in Sec 4 and NAOS CONICA operations in Sec 5 The templates which are used to acquire and observe targets and to obtain calibrations are described in Sec 6 Readers of this manual are encouraged to read this section carefully Transmission curves of the filters are given in Appendix A and the Preparation Software PS is described in Appendix B Additional information can be found at the following URL addresses e NAOS CONICA web pages http www eso org instruments naco e NAOS CONICA calibration plan http www eso org instruments naco e Call for Proposals for information on how to submit a proposal for NAOS CONICA http www eso org proposals e Exposure Time Calculator http www eso org observing etc 2 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Catalogues for adaptive optics reference objects Optical sources GSC2 at ESO skycat http archive eso org skycat or GSC2 at STScI http www gsss stsci edu Infrared sources http vizier u strasbg fr viz bin VizieR source 2MASS e NAOS Preparation Software http www eso org observing etc naosps doc Phase II Proposal Preparation http www eso org observing p2pp and notes
112. l just nod between A and B If the parameter Return to Origin T F is set to true T the telescope returns to the starting position If not the telescope is not moved The NEXPO per offset position parameter defines the number of frames stored per A or B position If for example DIT 120s NDIT 1 NEXPO per offset position 8 8 images will be stored for each position If in addition the Number of AB or BA cycles is set to 2 the template will deliver in total 32 images 8 for the first A position 16 for the B position and 8 for the second A position The total integration time excluding overheads is 64 minutes Note in the case where there are several OBs using this template on the same target for several hours of integration on the same target it is recommended to modify the Nod throw parameter by a few arcseconds between each OB This is for the following reason the acquisition is always done at the same position on the array i e center of the slit Therefore different executions of the same template will position the targets at the same positions along the slit and the spectra will fall at the same positions on on the detector Therefore 72 NAOS CONICA User Manual VLT MAN ESO 14200 2761 even if you define some non zero value for the Jitter Box Width parameter it is recommended to give the Nod throw parameter different values between OBs so as to get the spectra at different positions across the array When
113. ld centering on their Finding Charts and or in their README file Table 34 describes the parameters of this template Table 34 Parameters of NACO_img_acq_SDIMoveToPixel P2PP label Default Description DIT NODEFAULT Detector Integration Time secs NDIT NODEFAULT Number of DITs PSF reference T F F PSF reference T F RA offset arcsec 5 RA offset for fixed pattern arcsec DEC offset arcsec 5 DEC offset for fixed pattern arcsec Position Angle on Sky 0 Position angle in degrees Add Velocity Alpha 0 Additional tracking vel in RA Add Velocity Delta 0 Additional tracking vel in DEC Neutral density filter Full Neutral density filter Type of AO Observation LGS NGS NODEFAULT LGS or NGS observation type Camera NMODEFAULR SDI or SDI camera NAOS parameter file NODEFAULT NAOS parameter file ln arcsec sec In order for faint objects to be clearly seen an image of the sky is acquired in an offset position defined by the RA offset arcsec and DEC offset arcsec parameters This image is then subtracted from NAOS CONICA User Manual VLEMAN ESO 14200 2761 57 all images that are subsequently displayed on the RTD The integration time for these acquisition images is defined by the DIT and NDIT parameters This template records an image of the field after the acquisition has been completed If three images are recorded then the first two are images of the reference and they are used by the operator to help classify the OB 6 4
114. le of 25 the PSF is attenuated by 20 at 150mas and less than 4 at 300 mas The blue curve showed in Figure 15 has been corrected from this effect by dividing the detection level calculated on the double roll subtraction images by the theoretical attenuation This last technique is outperforming all the others except at very short angular separation less than 0 15 where the SDI subtracted by a SDI reference is better However since it does not use a reference image the recorded time on the studied star is doubled for a given observing time For this reason we advise to record images with rotation steps of the instrument and use this double roll subtraction technique to improve at its best the efficiency of the instrument In terms of operations the rotation of the instrument is already implemented in the templates and is not time consuming However during the rotation the position of the star is changed compared to the coronagraph mask and a re centring is mandatory albeit time consuming 4 4 3 Calibration plan and night flats The calibration plan does not support SDI 4 4 4 4 Night flat fields SDI 4 is more affected by dust than those of 4QPMs The same recommendations issued for 4QPMs hold for SDI 4 Imperfections on the plates that hold the 4QPMs together with instrument flexure means that flat fields depend on the rotator angle For this reason the template NACO_coro_cal_NightCalib allows one to take night time flat fields immediate
115. ly after SDI 4 data have been taken We strongly recommend that these calibrations are taken for the said setup Night time flat fields with the fully opaque masks are not needed These flats are taken without the mask 4 4 5 Pipeline SDI 4 observations are not supported by the pipeline or the ETC 4 5 Spectroscopy Table 10 summarizes the main characteristics of the long slit spectroscopic modes NAOS CONICA User Manual VLEMAN ESO 14200 2761 27 4 5 1 Slits Two long slits and a slitless mode are available for spectroscopy The characteristics are listed in Tab 9 Slitless spectroscopy is done with the FLM_13 mask which is the field mask used for imaging with the S13 objective and it is available for the SW grism modes only The centering of the observed object in the slit or to the center of the mask in the case of slitless spectroscopy is done interactively through an acquisition template Table 9 Available slits in CONICA Name Dimensions Comments Slit 86mas 86 mas x 40 arcsec For S L27 camera the slit length is 28 arcsec Slit_172mas 172 mas x 40 arcsec For S L27 camera the slit length is 28 arcsec Slitless 14 arcsec x 14 arcsec For the SW spectroscopic modes only 4 5 2 Spectroscopic modes A spectroscopic mode is made up of a grism an order sorting filter and an objective Details of the offered spectroscopic modes are given in Table 10 The mode name is the identifier given to the mode and it is used in P2
116. ly one value if one parameter is not changed Unlike other templates this template does not have a Return to Origin T F flag This flag refers to the spatial offsets only and the template will do this automatically before rotating the rotator to the new position Table 43 describes the parameters of this template Table 43 Parameters of NACO_sdi_obs GenericOffset P2PP label Default Description DIT NODEFAULT Detector Integration Time secs Readout mode Double _RdRstRd Readout mode List of NDITs NODEFAULT List of NDITs NEXPO per offset position 1 Number of exposures per offset position Number of offset positions NODEFAULT Number of offset positions Observation Type 0 or S NODEFAULT O is with AO S is without List of offsets in X NODEFAULT Offset in arcseconds List of offsets in Y NODEFAULT Offset in arcseconds Return to the Original Return to original rotator Rotator Position T F F position at end of the template List of Position Angle Offsets NODEFAULT List of rotator offsets in degrees Neutral density filter Full Neutral density filter Camera NODEFAULT SDI or SDI camera Rotator offset angles are entered as a list The angles are relative so a sequence with 0 33 0 33 would result in images that are taken 0 33 33 and O degrees from the original rotator position Due to difficulties in NAOS CONICA User Manual VLEMAN ESO 14200 2761 69 compensating for rotator offsets with the FS we are presently requesti
117. mask in both the acquisition and observing template s NAOS CONICA User Manual VLEMAN ESO 14200 2761 37 This template provides interactive tools to center objects in the center of the selected mask which is overlaid on the RTD 5 8 Pre Imaging As of P78 a pre imaging mode is offered It is offered for programs where critical conditions need to be checked to guarantee the successful execution of the science program This mode ensures a quick delivery of the data to the user and is restricted to e programs that have already requested a separate pre imaging Run or otherwise indicated an amount of time to be used for pre imaging Examples of cases that may require pre imaging are programs needing to check either the field orientation because of possible contamination by a close by bright star or the possible binarity of potential targets for occultations or to refine the slit position in a crowded field e to 2 imaging templates only NACO_img_obs_AutoJitter amp NACO_img_obs GenericOffset For these 2 templates a new user selectable keyword Observation Category has been introduced and should be set to PRE IMAGE in the above mentioned cases only By default this parameter is set to SCIENCE Failure set this keyword properly will result in delays to process and deliver the pre imaging data 5 9 Finding Charts README Files and OB Naming Conventions In addition to the general instructions on finding charts and README files that
118. n Angle 45 deg Conica FOV 28 for S27 1 1 x Figure 19 An illustration of how the NACO_img obs_AutoJitter template works with Jitter Box Width 10 NEXPO per offset position 1 Number of offset positions 7 Return to Origin T F T Camera S27 The last dashed line joining 7 to 1 is the offset at the end of the template since the Return to Origin T F was set to T The dotted box defines the Jitter Box Width offsets are generated Defining too wide a box may lead to poor image overlap Conversely too small a value may lead to poor sky subtraction near extended objects By construction there is no telescope offset before the first exposure If the parameter Return to Origin T F is set to true T the telescope moves back to its original position at the end of the template If not the telescope is not moved The total integration time excluding overheads is defined in seconds by DIT x NDIT x NEXPO per offset position x Number of offset positions 6 5 3 NACO_img_obs_GenericOffset This template is used for imaging and has the flexibility to do any sequence of telescope offsets either in detector or sky coordinates Table 40 describes the parameters of this template Telescope offsets are defined as lists with the parameters List of offsets in RA or X and List of offsets in DEC or Y The offsets are relative to the previous position are in RA and DEC or in X and Y depending on the Offset Coordinate
119. ndard stars 2 2 oo e e 19 Magnitude limits for DIT lt 1 2 2 0 2 0 2 02 e 20 Overheads s 2 2 ad ere ha PG rt qs we due We doe a ee a 21 Overheads Example 1 Imaging a faint source V 15 for visual WFS or K 10 for IR WFS with FowlerNsatip 2 26 ce n a we Be ae a a ee e 22 Overheads Example 2 Imaging a bright source V 11 with the visual WFS or K 7 with the IR WFS with Double RdRstRd 2 a 23 Overheads Example 3 Imaging a bright source in the L band V 11 for visual WFS or K 7 for IR WES with Uncorr s A a a a E E A A 24 Overheads Example 4 Spectroscopy of a faint source with FowlerNsamp 25 Overheads Example 5 Polarimetry of a bright source with the Wollaston 26 Overheads Example 5b Polarimetry of a bright source with the Wollaston amp HWP 27 Overheads Example 6 SW Coronography of a bright source with Double RdRstRd 28 Overheads Example 7 LW Coronography of a bright source o 29 Overheads Example 8 Imaging with chopping o e 30 Overheads Example 9 Imaging a faint source with the FP 31 Overheads Example 10 A bright source with SDI o o 32 NACO templates cookbook o e 33 Parameters of NACO_img_acq_MoveToPixel ene 34 Parameters of NACO_img_acq SDIMoveToPixel
120. ng observers to keep the relative offset angle to 45 degrees or less Additionally the user can choose to rotate the rotator to the original rotator position once the template has ended with the parameter Return to the Original Rotator Position T F For observations with NAOS CONICA the default value for this flag is False The total number of exposures is given by the number of rotator positions x Number of offset positions x NEXPO per offset position With this scheme it is possible for the user to sample the object and the sky as desired at several rotator positions It is also possible to code the template so that the object and sky is sampled as desired for one angle only The template can be restarted with another orientation on the sky for another series of exposures The total integration time excluding overheads is defined in seconds by DIT x NDIT x NEXPO per offset position x Number of offset positions x the number of rotator positions 70 NAOS CONICA User Manual VLEMAN ESO 14200 2761 6 7 Spectroscopic Templates 6 7 1 Introduction For SW observations the readout mode of the detector can be set to either FowlerNsamp or Double RdRstRd for LW observations the readout mode will be set to Double _RdRstRd The width of the slitless mask is 13 arc seconds which is half the length of the regular slits Users should keep this point in mind when programming the offsets For the NACO_spec_obs_AutoNodOnSlit and NACO_spec_cal_
121. ngular distance to the science target mandatory parameter The other columns are filled when requesting an optimization by the PS server section B 6 If several reference objects are available in the table you can select the one you want to work with by simply clicking on the corresponding row This will update the contents of the form below the table as well as the Resulting Performance sub panel shown on the bottom left of the GUI Indeed each reference object is attached to its own configuration of the AO system and to the performance estimated when considering this configuration The order is important if the first reference object is acquired successfully then the other reference objects will not even be considered Reference objects should be sorted in decreasing order of expected performance Use the list manipulation buttons Up Down to modify this order as needed Every time you want to add an object to the list you must first fill in the mandatory fields and then click the button labeled Register Object at the bottom of the reference object form The mandatory fields are e the coordinates of the reference which sets the distance to target 92 NAOS CONICA User Manual VLEMAN ESO 14200 2761 e the reference brightness and e the reference morphology If the reference object is the target one can use the Target gt Reference Object option from the Objects menu at the top of the panel as a shortcut For test purposes the
122. nimised all object frames have the same position angle on sky The technique has proved to be efficient with SOFI and ISAAC For NAOS CONICA it is not required for observations with the SW filters but it may be needed for the LW filters In addition the template provides the flexibility to adjust the number of NDIT sub integrations for the OBJECT and SKY frames NDIT for the OBJECT positions defines the number of sub integrations on the object and NDIT for the SKY positions defines the number of sub integrations on the sky The total integration time excluding overheads is defined in seconds by DIT x NDIT for the OBJECT positions NDIT for the SKY positions x NEXPO per offset position x Number of AB or BA cycles Thus the total integration time on the sky and on the object can be adjusted so that the S N on the object is optimised Remember that the 30 second per telescope position rule means here that both DIT x NDIT for the OBJECT positions x NEXPO per offset position plus overheads and DITx NDIT for the SKY positions x NEXPO per offset position plus overheads shall each exceed 30 seconds of time Fig 22 illustrates how this template can be used 66 NAOS CONICA User Manual VLEMAN ESO 14200 2761 NACO_img_obs_FixedSkyOffset N DEC Offset Sky Positions Object Positions RA Offset Figure 22 An illustration of how the NACO_img_obs_FixedSkyOffset template works with Jitte
123. number of offsets NOFF_IMG are free parameters Table 49 describes the parameters of this template Table 50 Parameters of NACO_coro_obs_Astro P2PP label Default Description NDIT img NODEFAULT Number of DITs per image for the imaging DIT coro NODEFAULT DIT secs for the coronagraphy DIT img NODEFAULT DIT secs for the imaging no mask Readout mode Double RdRstRd Readout mode Jitter Box Width NODEFAULT Jitter Box Width Sky only NDIT for object positions NODEFAULT Num of DITs at the obj position under the mask NDIT for sky positions NODEFAULT Num of DITs at the sky position with the mask NEXPO Obj only coro NODEFAULT Num of exp with target under the mask NEXPO per offset position img NODEFAULT Num of exposures per imaging position NOFF sky only coro NODEFAULT Num of offsets pos on sky with the mask NOFF img NODEFAULT Num of offsets positions for the imaging Offset Coordinates NODEFAULT SKY or DETECTOR List of offsets in X NODEFAULT Offset in arcseconds List of offsets in Y NODEFAULT Offset in arcseconds Filter coro NODEFAULT Filter Name for the coronagraphy Filter img NODEFAULT Filter Name for the imaging Mask Position NODEFAULT Coronagraphic mask Neutral density filter Full Neutral Density Filter Camera NODEFAULT Camera Name The total integration time excluding overheads is defined in seconds by the sum of the CORO time and IMAGING time time spend on each mode respec
124. on Initial Setup AO acquisition SDI acquisition Sub total NACO_img_acq_SDIMoveToPixel NACO_sdi_obs_GenericOffset 10 seconds 6 5 1 Double_RdRstRd 0 33 F 3 minutes 0 75 minutes 2 minutes 5 minutes 1 minutes 11 75 minutes Observation at 0 degrees 5 27 6 10 0 7 Rotator offset Observation at 33 degrees 5 27 6 10 0 7 Total Overheads 7 3 minutes 1 minute 7 3 minutes 27 3 minutes 173 Observation Number of offset positions x Offset overhead NDIT x DIT readout overhead NAOS CONICA User Manual VLEMAN ESO 14200 2761 51 6 NAOS CONICA templates 6 1 Templates The instrument detector and telescope are controlled by Observing Blocks OBs which are made up of templates Templates are divided into three categories acquisition observation and calibration Usually OBs consist of an acquisition template and one or more observation templates for nighttime observa tions and in some limited cases an additional nighttime calibration template Only one acquisition template is allowed in an OB and therefore only one preset on sky It is not possible e g to group in the same OB observation templates on the science object and calibration template on a standard star Table 32 provides a short summary of the templates offered for period 81 These templates should cover most needs If this is not the case users must contact the User Support Department usd help eso org well before t
125. one without the focal plane masks e Detector darks in all readout modes and DITs 4 3 7 Night flat fields Imperfections on the plates that hold the semi transparent Lyot mask and the 4QPMs together with instrument flexure means that flat fields depend on the rotator angle The template NACO_coro_cal NightCalib allows one to take night time flat fields immediately after coronagraphic data have been taken We strongly recom mend that these calibrations are taken for the said masks Night time flat fields with the fully opaque masks are not needed These flats are taken without the mask Given the low transmissivity of the semi transparent spot it is practically impossible to normalise the response of the spot relative to the response outside it i e absolute flatfielding inside the spot is very difficult One can remove the pixel to pixel sensitivity variations by using a flat that is taken without the coronagraphic plate but this kind of flat does not remove dust features that are on the plate 4 3 8 Pipeline Coronagraphic observations are not supported by the pipeline 4 4 Simultaneous Differential Imaging plus coronagraphy SDI 4 is a new mode of NaCo offered as of P81 April 2008 It was commissioned together with the new 4QPMs by a team from LESIA Observatoire de Paris led by A Boccaletti and collaborators J Baudrand P Riaud and P Baudoz NAOS CONICA User Manual VLEMAN ESO 14200 2761 23 Figure 13 Flat field of the
126. or the tip tilt motions which are not sensed by the LGS The NGS has to be in the V magnitude range 12 17 and can be as far away as 40 from the science target however with decreasing performance with increasing distance At 40 distance about half the Strehl ratio is achieved as compared to having the NGS on axis with the LGS It is also important to remember that due to the Cone effect the maximum strehl achievable with the LGS is significantly less than the one obtained with a bright natural guide star 45 against 60 in K band with the AO reference on axis For information the LGS is expected to have a magnitude equivalent to that of a star in the range mV 11 13 In order to apply for the LGS mode just make sure that you have a natural guide star within 40 from your object and that no other mode can be used It should be stated clearly in the proposal why only this mode can 42 NAOS CONICA User Manual VLEMAN ESO 14200 2761 be used and which NGS will be used for tip tilt sensing There are borderline cases when one has to decide whether to select LGS or NGS mode The limiting magni tude is currently 13 5 14 i e with AO reference stars which are fainter than this limit one should select LGS mode and keep the star as a tip tilt reference Brighter stars offer better performance in NGS mode When using the PS a good rule of thumb is the following if the expected Strehl ratio calculated for the NGS mode is 10 or higher stay with
127. orting filters 87 A 2 CONICA Neutral density filters 2 2 0 00 0 0 000 000 000000000 88 B Preparation Software 89 Bl Starting p the PS sos coe tangala ee ee 89 B 2 Graphical User Interface Overview ee 89 B 3 Target amp Instrument Setup 90 Ba Sky Conditions Any else o o AE aA A e ee amp a io 91 B3 Reference ODJECtS s 0000 ra ds a AA AA 91 B 5 1 Handling several reference objects 2 0 o e ee 91 B 3 2 Morphology vico ri a oe A RS 92 B 5 3 PhOtOMetry 0 a o Oe AR ce ater 93 B 5 4 Tracking table ee 93 B 6 Optimizing NAOS and Getting a Performance Estimation o o 94 B 7 Exporting to the Exposure Time Calculator 2 2 0 20 02002 e 97 B 8 Exporting to PZPP dla o Qh de ias e eh e ee Se A Sw Se ala A 97 B 9 Exporting OBs from P2PP 1 2 20 0 a a a E a ee 98 B 10 Saving Restoring a PS Session 2 2 ee 98 B 11 Giving names to session P2PP and PSF files o o e e 98 Vili NAOS CONICA User Manual VLT MAN ESO 14200 2761 B12 User s preferences oia a eae e a te Ra eed AE a ee Ee SS 98 NAOS CONICA User Manual VLT MAN ESO 14200 2761 1x List of Figures 1 Principle of Adaptive Optics ee 4 2 Atmospheric transmission spectrum 1 5 microns e e 6 3 NAOS optics and mechanics 1 2 ee 8 Ae SLGSPAUTA SS teks Shue bao AG SA be aes oe a eae eas a
128. osition Due to difficulties in compensating for rotator offsets with the FS we are presently requesting observers to keep the relative offset angle to 45 degrees or less Additionally the user can choose to rotate the rotator to the original rotator position once the template has ended with the parameter Return to the Original Rotator Position T F For observations with NAOS CONICA the default value for this flag is False After each rotator offset the telescope can offset according to a user defined list Spatial offsets are defined with the parameters List of offsets in X and List of offsets in Y The offsets are relative to the previous position are in X and Y and are defined in arcsec Additionally the observation type can be defined for each image and is entered as a list in the parameter Observation Type 0 or S O stands for Object and assigns the DPR TYPE header keyword to OBJECT S stands for Sky and assigns the DPR TYPE header keyword to SKY The AO loop is closed for the former and open for the latter The total number of spatial offsets is defined by the parameter Number of offset positions This num ber can be different from the number of elements in the aforementioned lists If the number of spatial offsets is larger than the number of elements in a list the list is restarted from the beginning as many times as needed until the correct number of offsets have been done These lists can have any length however havin
129. paration of the Wollaston prism The average beam separation corresponds to about 3 3 separation pixel arcsec on the sky resulting chromatic error is about 86mas The Wollaston can also be used with the LW filters however the beam separation is less and there is slight overlap between the ordinary and extraordinary beams Four wire grid analysers See Tab 13 are mounted in the grism wheel Unlike the Wollaston the entire FOV is available However to obtain the Stokes parameters an image with each of the analysers hence four images in total or with four different rotator angle or with 4 different angles of the half wave plate is required Table 13 The names of the wire grid analysers and the angle at which they are mounted Angle degrees Pol_00 Pol_45 Pol_90 Pol_135 Since the J band filter is in the same wheel as the Wollaston prisms and the wire grids J band Polarimetric observations are not possible The instrument induced polarisation as for all Nasmyth instruments is a function of the parallactic angle it is generally of the order of 2 but can be as high as 4 If users do not take care in determining the instrument induced polarisation then it is not possible to get meaningful estimates of the polarisation unless sources are more than 3 polarised In general we recommend that users come as visitors if they wish to measure the polarisation of sources that are less than 5 At this stage we do not know
130. plates make extensive use of telescope offsets In some templates the offsets are set automatically e g NACO_img_obs_AutoJitter but in others the offsets have to be entered manually as lists In this latter case the convention is that offsets are relative E g the following list of offsets RA offset list arcsec 010 10 20 20 DEC offset list arcsec 00000 will result in a first image without offset a second image in which the telescope was moved 10 arcseconds East a third image at the original position etc Sometimes offsets may be defined in detector coordinates In that case a positive offset in X will move the image to the right X the telescope offset is therefore in the opposite direction All offsets are defined in arcseconds even the offsets that are defined in detector coordinates Therefore an offset of 10 in X will move the object 10 arcsec to the right Reminder the minimum time between exposures is 30 seconds NAOS CONICA User Manual VLEMAN ESO 14200 2761 55 6 4 Acquisition Templates 6 4 1 Introduction Telescope presets can only be done via acquisition templates and all observing blocks must start with one There are six acquisition templates two for imaging and wire grid polarimetry and one each for SDI imaging spectroscopy coronagraphy and polarimetry with the Wollaston They are listed in Table 32 All acquisition templates preset the telescope to the AO reference star set up NAOS and CONICA close
131. r NACO_img_obs_FixedSkyOffset NACO_img_obs_GenericOffset NACO_sdi_obs_GenericOffset Spectroscopy Spectroscopy of point like or moderately extended objects Spectroscopy of extended objects i e wider than 10 arc seconds or complex sequences of slit positions NACO_spec_obs_AutoNodOnSlit NACO_spec_obs_GenericOffset Polarimetry Imaging Polarimetry Polarimetry with Half Wave Plate NACO_pol_obs_GenericOffset NACO_pol_obs Retarder Coronagraphy Coronagraphy without chopping SDI 4 4QPM Coronagraphy with SDI NACO_coro_obs_Stare NACO_coro_obs_Astro NACO_sdi4_obs_Stare Standard Stars Standard Star Imaging Standard Star Fabry Perot Imaging Standard Star Coronagraphy Standard Star Spectroscopy Standard Star Polarimetry NACO_img_cal_StandardStar NACO_fpi_cal_StandardStar NACO_coro_cal_StandardStar NACO_spec_cal_StandardStar NACO_pol_cal_StandardStar Night Time Calibrations Night time Coronagraphic and SDI 4 Flats Night time Spec Flats and Arcs NACO_coro_cal_NightCalib NACO_spec_cal_NightCalib NAOS CONICA User Manual VLEMAN ESO 14200 2761 53 e With the exception of standards the minimum amount of time between exposures is 30 seconds e Ensure that the correct filters are used when acquiring bright targets for spectroscopy See section 5 15 e When doing a blind offset from a bright reference object to a faint target we strongly recommend that the position angle be set so that the re
132. r Box Width 9 Number of AB or BA cycles 4 Sky offset in Dec 15 Sky offset in RA 35 Return to Origin T F T Camera S13 The AO loop is off when the sky is observed large filled in circles and on when the object is observed small filled in circles The dashed line connecting 8 with 1 is the offset done at the end of the telescope since Return to Origin T F is set to T The dashed box is defined by the Jitter Box Width NAOS CONICA User Manual P2PP label DIT Readout mode Jitter Box Width VLEMAN ESO 14200 2761 67 Table 41 Parameters of NACO_img_obs _FixedSkyOffset Number of AB or BA cycles NDIT for the OBJECT positions NDIT for the SKY positions NEXPO per offset position Return to Origin T F Rotate Pupil Sky offset in Dec Sky offset in RA Filter Neutral density filter Wire grid Camera 6 5 5 NACO_img_cal_StandardStar Default NODEFAULT NODEFAULT NODEFAULT NODEFAULT NODEFAULT 1 T F NODEFAULT NODEFAULT NODEFAULT Full empty NODEFAULT Double_RdRstRd Description Detector Integration Time secs Readout mode Jitter Box Width One cycle is an object sky pair Number of DITs at the object position Number of DITs at the sky position Number of exposures per offset position Return to origin at the end of the template Rotate the pupil in sky frames Declination offset in arcseconds RA offset in arcseconds Filter Name Neutral density filter Wire grid
133. randomly distributed around the initial telescope position and within a box whose dimensions are set by the parameter Jitter Box Width in arcsec The sky positions are randomly distributed around a position that is set at a constant distance defined by the 64 NAOS CONICA User Manual VLEMAN ESO 14200 2761 NACO_img_obs_GenericOffset 1024 1024 Y E N Position Angle 45 deg 4 3 5 8 1 2 7 6 CONICA FOV 28 for S27 1 0 x Figure 20 An illustration of how the NACO_img_obs GenericOffset template works In this example the offsets are in DETECTOR co ordinates Exposures 1 and 5 occur at the same place and the telescope will not return to the origin after the eighth exposure The parameter settings for this example were NEXPO per offset position 1 Number of offset positions 8 Return to Origin T F F Camera S27 Observation Type 0 or S O Offset Coordinates DETECTOR List of offsets in RA or X 030 300 30 List of offsets in DEC or Y 0070 7 707 parameters SEQ SKYOFFSET DEC and SEQ SKYOFFSET RA from the original telescope position and within a box whose dimensions are set by the parameter Jitter Box Width in arcsec This template is similar to the the NACO_img_obs_AutoJitterOffset template but instead of a randomly positioned sky frame the user specifies the exact location of the sky frame through the SEQ SKYOFFSET DEC and SEQ SKYOFFSET RA keywords The object positions
134. re used by the operator to help classify the OB NAOS CONICA User Manual VLEMAN ESO 14200 2761 61 6 5 Imaging and Wire Grid Polarimetry 6 5 1 Introduction For observations with the SW filters the readout mode of the detector should be set to either Double RdRstRd or FowlerNsamp For observations with LW filters the readout mode should be set to Uncorr All imaging templates make use of the NEXPO per offset position parameter It is the number of exposures one exposure DIT x NDIT per offset position For very bright targets see Sec 5 15 a neutral density filter can be inserted into the light path The choices are Full for no neutral density filter ND_Long for a LW neutral density filter and ND_Short for a SW neutral density filter For polarimetry with the wire grids set the Wire grid parameter to one of the four wire grids See Tab 13 For imaging observations set this parameter to empty Note that wire grid polarimetry observations can also be performed with the half wave plate with the special template NACO_pol_obs Retarder see 6 8 3 For LW observations without chopping only the NACO_img_obs_AutoJitter template should be used The sky subtraction with the other templates is generally unsatisfactory 6 5 2 NACO_img_obs_AutoJitter This template offsets the telescope between exposures according to a random pattern of offsets automatically determined by the template It is ideal for long integrations on sparse fields and do
135. re was taken to minimize differential static aberrations between the four beams lt 10nm RMS per Zernike mode resulting in PSFs and speckle noise distributions that are almost identical The mask used to be tilted but this has been fixed in June 2005 so that the FOV is indeed 5x5 untilted See Fig 6 for details Please note that in Fig 6 CONICA was not aligned Please check regularly following webpage for the latest news and image of the SDI mask http www eso org instruments naco news html The new SDI mode is based on the same principle but the four images are placed on a square The Field of View is bigger 8x8 Please note that in the image Fig 7 the alignment was not optimum One aligns CONICA so that each square appears aligned with the rows and columns of CONICA however the vertical vignetting will always remain it cannot be suppressed due to physical limitation of the system Please check http www eso org instruments naco inst New_cfp81 html for details of performance of this new SDI mode offered in visitor mode as of period 80 The SDI has been designed to detect methane rich objects near very bright stars To give an approximate idea of the performance contrasts as high as 30 000 between a bright H lt 7 mag primary star and a methane rich object Teff lt 1000 K can be obtained in 40 min with a signal to noise ratio of 6 The SDI modes of CONICA is not supported by either a pipeline or an ETC 4 3 Coronagraph
136. relevant to NAOS CONICA http www eso org observing p2pp NACO NACO P2PP html e NACO Quality control http www eso org observing dfo quality Should you have any question regarding NAOS CONICA operations the point of contact is the User Support Department usd help eso org in Garching 1 1 Current version of this User Manual This is version 81 of the NAOS CONICA User Manual applicable for phase I preparation for period 81 Since NAOS CONICA is in constant improvement and modes are refined especially the new ones it is advisable to check the NAOS CONICA web page for possible updates to this manual and for recent news 1 2 Changes for period 81 The following changes are implemented for P81 e In addition to the newly commissioned modes offered in P80 in P81 a new mode which combines simultaneous differential imaging and coronagraphy SDI with 4QPM optimized for H band dubbed SDI 4 is offered in VM only This mode is expected to improve the search for methane companions like giant extrasolar planets around nearby stars e Fabry Perot imaging is not offered e Chopping will not be supported in P81 All modes requiring chopping imaging and polarimetry in M and coronagraphy with LW filters will not be offered e Coronagraphy with the semitransparent mask and the S13 camera is not recommended since the spots are at the edge of the available field of view Valid changes introduced in P80 e The old 4QPM corona
137. rgets but is fine for different OBs using the same target The configuration file is inserted into the NAOS parameter file keyword of the relevant acquisition template The Strehl seeing and airmass constraints and the RA and DEC fields of P2PP will be automatically filled when the configuration file is loaded Do not edit these fields B 9 Exporting OBs from P2PP The export facility in P2PP allows one to export observing blocks For NAOS CONICA two files are pro duced one with the extension obx and another with the extension aocfg These files should be kept in the same directory P2PP will report an error if the two files are in different directories B 10 Saving Restoring a PS Session The complete PS session can be saved on local disk and restored The Save Session and Load Session func tions available from the File menu of the main panel allow you to save or load the corresponding information on your disk Please be aware that loading a previously saved session file will discard all the data currently stored in the interface However it does not alter any of the configuration files that have been saved to disk Only the files with an extension jnps can be loaded into the PS Once a previous session is loaded into the PS one should run the optimization again before exporting to P2PP otherwise a corrupted file may be exported and the observation may be impossible In case one forgot to save a session it is possible to copy the
138. rn arcsec DEC offset arcsec 5 DEC offset for fixed pattern arcsec Position Angle on Sky 0 Position angle in degrees Add Velocity Alpha 0 Additional tracking vel in RA Add Velocity Delta 0 Additional tracking vel in DEC Filter NODEFAULT Filter Name Neutral density filter Full Neutral density filter Camera NODEFAULT Camera Name Slit NODEFAULT Slit Name Type of AO Observation LGS NGS NODEFAULT LGS or NGS observation type NAOS parameter file NODEFAULT NAOS parameter file 1 Tn arcsec sec The Alpha offset from Ref Star and Delta offset from Ref Star parameters allow the user to define a telescope offset when the acquisition is made on a bright reference object That is once the reference object has been acquired and centered in the slit the offsets defined here will offset the telescope so as to bring the desired target into the slit Given the accuracy at which the offsets are likely to be defined the smallest slit is only 86mas wide so the computed offsets have to be better than a few tens of mas we do not recommend 58 NAOS CONICA User Manual VLEMAN ESO 14200 2761 this option to users If there is no other option then the position angle of the slit should be set so that both the reference source and science target are in the slit at the same time These offsets should not be confused with the RA offset arcsec and DEC offset arcsec offsets which are used to define the offset between the target and a sky image which is s
139. roughly equivalent on an 8 m telescope to the phase error experienced with an NGS 10 away from the astronomical target However contrary to the case of NGS only AO LGS based corrections saturate at a relatively low maximum K band Strehl ratio of 0 55 due to the cone effect Even more severe is the image motion or tilt determination problem Because the paths of the light rays are the same on the way up as on the way down the centroid of the artificial light spot appears to be stationary in the sky while the apparent position of an astronomical source suffers lateral motions also known as tip tilt The simplest solution is to supplement the AO system using the LGS with a tip tilt corrector set on a generally faint close NGS m 17 or brighter Performance is then limited by the poor photon statistics for correcting the tip tilt error The need of a natural guide star for tip tilt sensing is the reason why sky coverage cannot go up to 100 for LGS AO The Laser Guide Star Facility LGSF at UT4 is a joint project in which ESO are building the laser room beam relay and launch telescope while MPE and MPIA provide the laser itself The PARSEC project is based on a 4W CW Sodium Laser 589 nm focused at 90 km altitude in the meso sphere The thin layer of atomic sodium present at that height backscatters the spot image and produces in best conditions an mV 11 artificial star to guide the AO servo loop More typically the artificial guide
140. s NDIT of these before transferring the result to disk Note that the num ber of counts in the images always corresponds to DIT not to the total integration time i e DIT x NDIT 4 7 3 Readout Modes and Detector Modes The readout mode refers to the way the array is read out We offer three readout modes e Uncorr The array is reset and then read once It is used for situations when the background is high eg LW imaging The minimum DIT without windowing is 0 1750 seconds For observations in M the array is windowed to 512x514 and the minimum DIT is 0 0558 seconds 32 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Figure 16 Illustration of the ghosts present on CONICA images when observing a bright object In addition to the electronic ghosts there is also an optical ghost characterised by its circular shape The electronic noise visible on the sides of the array as well as the bias level of rows 512 amp 512 disappear in the background subtraction e Double_RdRstRd The array is read reset and read again It is used for situations when the background is intermediate between high and low Eg SW imaging or LW spectroscopy The minimum DIT is 0 3454 seconds e FowlerNsamp The array is reset read four times at the beginning of the integration ramp and four times again at the end of the integration ramp Each time a pixel is addressed it is read four times It is used for situations when the background is low Eg SW sp
141. s at the sky position is defined by the Number of offset positions Sky only and the telescope can offset between these exposures The sky positions are randomly distributed around a position that is set at a constant distance defined by the parameters SEQ SKYOFFSET DEC and SEQ SKYOFFSET RA from the original telescope position and within a box whose dimensions are set by the parameter Jitter Box Width in arcsec It is strongly recommended especially for very bright sources to select an area so that the main target is out of the field of view for sky measurements to avoid saturation effects The coronagraphic mask is left in the beam for the sky exposures The object positions will be observed with the AO loop closed The sky positions will be observed with the AO loop open Table 53 describes the parameters of this template Table 53 Parameters of NACO_sdi4_obs_Stare P2PP label Default Description DIT NODEFAULT Detector Integration Time secs Readout mode Double_RdRstRd Readout mode Jitter Box Width NODEFAULT Jitter Box Width Sky only Number of AB cycles NODEFAULT Num of AB cycles E g 2 for ABAB NDIT for the OBJECT positions NODEFAULT Num of DITs at the object position NDIT for the SKY positions NODEFAULT Num of DITs at the sky position Number of Exposures Object Only NODEFAULT Num of exposures on target Number of offset positions Sky only NODEFAULT Num of exposures on sky Sky offset in Dec NODE
142. s no longer needed and it has been decommissioned Depending on the morphology and brightness of the target the service observer will measure the Strehl ratio on the reference source and a preliminary classification will be made If the reference is extended too faint or too bright the measurement will not be made and the OB classification will be based on the performance that is computed by the RTC If we believe that we have achieved a Strehl Ratio which is greater than 50 of that requested by the user we will consider that the OB has been successfully completed in the event that all other constraints are met satisfactorally We are considering a similar classification scheme for the LGS operation Once completely decided a full update will be posted on the NaCo webpages http www eso org instruments naco news html 5 11 1 PSF Reference Stars Observations of PSF stars are frequently used in the analysis of AO data Generally speaking the instrument set up should not change between the observation of the science target and the PSF reference the brightness of the two should be similar and atmospheric conditions should be stable With NAOS CONICA the simplest way of ensuring that the instrument configuration does not change is to ensure that the PSF reference T F flag in the acquisition template is set to T When this flag is T the telescope will preset to the target the operator will acquire the target and AO will start without chan
143. s parameter and are defined in arcsec Additionally the observation type can be defined for each image and is entered as a list in the parameter NAOS CONICA User Manual VLEMAN ESO 14200 2761 63 Table 40 Parameters of NACO_img_obs_GenericOffset P2PP label Default Description Observation Category SCIENCE Observation Category DIT NODEFAULT Detector Integration Time secs Readout mode Double_RdRstRd Readout mode List of NDITs NODEFAULT List of NDITs NEXPO per offset position 1 Number of exposures per offset position Number of offset positions NODEFAULT Number of offset positions Observation Type 0 or S NODEFAULT O is with AO S is without Offset Coordinates NODEFAULT SKY or DETECTOR List of offsets in RA or X NODEFAULT Offset in arcseconds List of offsets in DEC or Y NODEFAULT Offset in arcseconds Return to Origin T F T Return to the origin at the end Rotate Pupil F Rotate the pupil in sky frames Filter NODEFAULT Filter Name Neutral density filter Full Neutral density filter Wire grid empty Wire grid use empty for imaging Camera NODEFAULT Camera Name Observation Type O or S O stands for Object and assigns the DPR TYPE header keyword to OB JECT S stands for Sky and assigns the DPR TYPE header keyword to SKY The AO loop is closed for the former and open for the latter The total number of offset positions is defined in the parameter Number of offset positions This number can be different from
144. should be aware that upto 1 hour of their time can be taken by the observatory to comply with its calibration plan Typically only 15 minutes are needed The calibrations taken usually involves twilight flat fields and imaging standards For spectroscopic observations the observatory automatically takes telluric standards for each setting used Visitors should think carefully about which telluric standards fundamental to remove telluric features should be observed The observatory staff will help them make the right choice Even though Paranal is an excellent site bad weather or poor and fast seeing can occur Visitors should come with backup programs particularly if the targets are in the North where on some occasions the wind can be strong enough to prevent the telescope from pointing in that direction Visitors should also prepare targets with bright V lt 10 reference sources so that telescope time can be effectively used when the turbulance is fast 5 3 Active optics and adaptive optics Active optics is the active control of the primary and secondary mirrors of the telescope Adaptive optics is the correction of wavefront errors induced by atmospheric turbulence NAOS CONICA User Manual VLEMAN ESO 14200 2761 35 Although the instrument can run in closed loop without the active optics system controlling the primary and secondary mirrors one gets better adaptive optics performance if the active optics system of the telescope is runnin
145. similar SNR in the image More important the reference MUST be observed with the same parallactic angle to have the same static speckle pattern which result of interaction between telescope and instrument aberrations and to match the spider spikes position in the images In practice the reference star has the same declination as the target but a right ascension which is that of the star plus or minus the OB duration reference is observed for the same amount of time as the target In general it is possible to found a reference star within less than 1 degree in declination and a few minutes in right ascension In these conditions an improvement of a factor 10 can be expected on the averaged contrast A contrast of 9 to 9 5mag is achievable at 0 5 in H and Ks Other techniques involving field rotation active or passive can be envisaged but not tested yet Given the above the use of the four quadrant phase mask is restricted to Visitor Mode observations Please refer to the webpage http www eso org instruments naco inst New _cfp81 html for more information 4 3 6 Calibration plan For coronagraphic observations a variety of calibration frames will be taken archived and updated at regular intervals The what when and how of calibrations is described in detail in the NACO Calibration Plan http www eso org instruments naos index html Documentation e Twilight flats and daytime lamp flats as described in Sec 4 1 3 These calibrations are d
146. star NAOS CONICA User Manual VLEMAN ESO 14200 2761 11 is in the range mV 11 13 This artificial reference star can be created at the position specified by the target coordinates and the NAOS visible wavefront sensor is used to correct the high order wavefront aberrations on the target object The laser is hosted in a dedicated laboratory under the Nasmyth platform of UT4 Fig 4 A custom made single mode fibre carries the high laser power to the 50cm launch telescope situated on top of the secondary mirror assembly providing the best possible artificial source image quality As a safety measure a twin whole sky camera with specialized software is used to monitor incoming aircraft and shut down the beam accordingly Figure 4 Illustration of the LGSF set up at UT4 the laser clean room is installed below Nasmyth A The laser beam is propagated via fiber to the launch telescope installed at the back of M2 12 NAOS CONICA User Manual VLEMAN ESO 14200 2761 4 CONICA CONICA is an IR 1 5 um imager and spectrograph which is fed by NAOS It is capable of imaging long slit spectroscopy coronagraphic and polarimetric observations with several different plate scales This section describes the optical components of CONICA See Fig 5 for a drawing of the instrument The optical path includes the following components the slider wheel which is either open closed in calibration position or with the Half Wave Plate in serted
147. th high proper motions and this usually means solar system objects the usual set of coordinates is not sufficient The user has to provide a separate tracking table giving the relative offsets between the AO reference object and the target in arcsec AO_reference science target coordinates as a function of universal time UTC An example of the format of this tracking table is given in Figure 32 The file containing the tracking data must be edited by hand and be available on the user s local disk Checking the Tracking Table check button below the coordinates entries enables the Choose File button next to it You can then attach your file to the selected reference object and the tracking table can also be seen via the View button which is enabled as soon as the file is attached Please note that the data of the tracking table are then copied into the interface which means that you do not need to keep the original file on your disk except of course if you want to edit your data You would then have to re attach the table to the reference object If you changed your mind and do not want the tracking table anymore just deselect the Tracking Table check button 94 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Figure 31 Illustration of the extinction curve used when giving a non zero value to the extinction A y The J H K and R bands are shown for reference along with the monochromatic wavelength for V The bottom graph represents the qu
148. the loop and acquire the science target All acquisition templates require a NAOS parameter file which contains information about the target the reference source the NAOS setup and other ancillary data Once this file is loaded the target fields in P2PP will contain the target coordinates The acquisition templates can take anywhere from one to five images during the acquisition process See the description of the individual acquisition templates for a description of what kind of images are recorded In general it is not necessary for the acquisition and the subsequent observation templates to have the same DIT and NDIT nor the same filter The detector and readout modes are not parameters of the acquisition templates They are automatically set and they depend on the filter For LW filters the readout mode is set to Uncorr and the detector mode is set to HighDynamic For all other filters the readout mode is set to Double_RdRstRd and the detector mode is set to HighSensitivity The minimum DITs for these modes are listed in Tab 15 For very bright targets see Sec 5 15 a neutral density filter can be inserted into the light path The choices are Full for no neutral density filter ND_Long for a LW neutral density filter and ND_Short for a SW neutral density filter Filter curves are plotted in Fig 29 All acquisition templates can be used to acquire PSF stars In such cases the PSF reference T F flag should be set to true Althoug
149. the Wollas ton prism will be used For each given offset position the template runs over the list of half wave plate angles before moving to the next offset position Only at the end of the OB does the telescope move back to the original position and the half wave plate to its default position i e 0 The angles in the list of half wave plate angle are relative one from the other e g 0 22 5 22 5 22 5 would correspond to an absolute rotation of 0 22 5 45 67 5 Note that the first angle provided is absolute since the HWP is always set to its zero position at the beginning of the template Once the template has run over the list of half wave plate angles the telescope can offset according to a user defined list Spatial offsets are defined with the parameters List of offsets in XandList of offsets NAOS CONICA User Manual VLT MAN ESO 14200 2761 77 NACO_pol_obs_GenericOffset CONICA FOV S27 28 1024 1024 1024 1024 Y Y 1 6 y 1 6 F x2 s5 x 8 2 XS 8 A EX lt Opaque strips gt eS x 3 4 9 3 4 9 1 1 N X 1 1 E N X Figure 25 An illustration of how the NACO pol obs GenericOffset template works with Number of offset positions 9 NEXPO per offset position 1 Observation Type 0 or S O List of offsets in X 400400400 List of offsets in Y 2 3 2 3 2 3 0 2 3 2 3 0 2 3 2 3 List of Position Angle Offsets 0 45
150. tively CORO exposure DIT_CORO NDIT_OBJ NEXPO_OBJ DIT_CORO NDIT_SKY NOFF_SKY IMG exposure DIT_IMG NDIT_IMG NEXPO_IMG NOFF IMG 6 9 4 NACO_coro_cal_NightCalib This template is used for taking night time flat fields and it should be placed immediately after the corona graphic or the SDI 4 templates 82 NAOS CONICA User Manual VLEMAN ESO 14200 2761 I ll Il 1 Coronography Generic Offset Coronography on target on sky Figure 27 Illustration of how the NACO_coro_obs_Astro template works The 3 phases of the template are presented Part I left coronagraphy without moving the telescope part II middle simple imaging the coronagraphic mask is removed Normally the first offset is zero to measure the exact position of the target out of the mask The last offset of the list NOFF_SKY bring you onto the sky position where the original coronagraphic mask is inserted again and on sky coronagraphic images are taken in open loop part II right diagram In this example NOFF_SKY 5 If Number of Night Flats is set to n where n can be from 0 to 3 n pairs of exposures are taken Each pair consists of one exposure with the flatfield lamp on and one exposure with the flatfield lamp off If is set to zero no lamp flats are taken The default is one This template should be used to take flats with the 4QPM the semi transparent coronagraphic mask and SDI 4 Only the SW filters ar
151. to Origin T F T Jitter Box Width 10 Execution time Preset 3 minutes Guide Star Acquisition 0 75 minutes Initial Setup 2 minutes AO acquisition 10 minutes Spectroscopic acquisition 5 minutes Through Slit 2 minutes Sub total 22 75 minutes Observation 2 6 27 300 2 65 8 minutes Total 88 6 minutes Overheads 48 Observation 2 x Number of AB or BA cycles x Offset Overhead DIT readout overhead NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 25 Overheads Example 5 Polarimetry of a bright source with the Wollaston Template parameters Acquisition Template Observation Template DIT NDIT Number of offset positions NEXPO per offset position Readout mode List of Position Angle Offsets Return to the Original Rotator Position Execution time Preset Guide Star Acquisition Initial Setup AO acquisition Polarimetric acquisition Sub total NACO_img_acq Polarimetry NACO_pol_obs_GenericOffset 10 seconds 6 5 1 FowlerNsamp 045 F 3 minutes 0 75 minutes 2 minutes 5 minutes 1 minute 11 75 minutes 8 3 minutes Observation at 0 degrees 5 27 6 10 2 Rotator offset Observation at 45 degrees 5 27 6 10 2 Total Overheads 1 minute 8 3 minutes 29 35 minutes 193 5 l Observation Number of offset positions x Offset overhead NDIT x DIT readout overhead NAOS CONICA User Manual VLEMAN ESO 14200 2761 47 Table 26 Overheads Example 5b
152. to help in classifying the OB are also taken NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 33 Parameters of NACO_img_acq MoveToPixel P2PP label Default Description DIT NODEFAULT Detector Integration Time secs NDIT NODEFAULT Number of DITs PSF reference T F F PSF reference T F RA offset arcsec 5 RA offset for fixed pattern arcsec DEC offset arcsec 5 DEC offset for fixed pattern arcsec Position Angle on Sky 0 Position angle in degrees Add Velocity Alpha 0 Additional tracking vel in RA Add Velocity Delta 0 Additional tracking vel in DEC Filter NODEFAULT Filter Name Neutral density filter Full Neutral density filter Camera NODEFAULT Camera Name Type of AO Observation LGS NGS NODEFAULT LGS or NGS observation type NAOS parameter file NODEFAULT NAOS parameter file ln arcsec sec 6 4 3 NACO_img_acq_SDIMoveToPixel This template is very similar to the NACO_img_acq MoveToPixel template with the exception that the camera and the filter are not parameters of the template It should only be used to aquire targets for SDI The template does a telescope preset and is followed by interactive centering of the object It must be followed by either an imaging template or an SDI template In visitor mode the interactive part of the template will be executed by the instrument operator under the supervision of the visiting astronomer In service mode itis mandatory that users provide detailed information for the fie
153. ts If you choose this op tion you will need to enter the apparent magnitude the filter in which the magnitude is measured either V J H K L or M and a spectral type The spectral type is chosen in an option button The list of available values is the same as that available in the interface of the CONICA ETC This ensures the compatibility between the two tools especially in the case when the target is also used as the reference object see also section B 7 e Magnitude Temperature The magnitude is given in the same way as above value filter but in this case the spectral energy distribution is modeled as a black body which requires a temperature Moreover the users now have the possibility to provide a visible extinction Ay value by default and if not specified this value is O and the PS behaves exactly as before When A y is defined it governs by how much the brightness of the AO reference target changes as function of the wavelength which is especially important due to the broad bandwidth of the wavefront sensor detectors We adopted a standard extinction law represented in Figure 31 as defined by Cardelli Clayton amp Mathis AJ 345 245 1989 section IIIb and expressed as lt A D Ay gt a x b x Ry with Ry Ay E B V 1 We set lt Ry gt to 3 1 which is an average value for the interstellar medium and is essentially independent of Ay for wavelength longer than 0 7m B 5 4 Tracking table For objects wi
154. ubsequently subtracted from all images This template records between 2 and 5 images to disk On some occasions the operator will record two images of the AO reference which are used to help classify the OB If this is the case the image of the slit will be the third frame recorded to disk otherwise 1t will be first The next image either the 2nd or the 4th image recorded to disk is an image of the acquisition target after 1t has been centered If reference offsets are used an additional image either the 3rd or the 5th image recorded to disk is taken after the reference offset 6 4 5 NACO_img_acq MoveToMask This template does a telescope preset and is followed by interactive centering of the object behind the coron agraphic mask It is very similar to the NACO_img_acq MoveToPixel template however it must be followed by a coronagraphic template A drawing of the selected mask is displayed on the RTD and is superimposed on the image of the field The centering of the target is then done interactively Acquisition must be done with the L27 objective for LW filters and can be done with either the S13 or S27 objectives for SW filters For precise centering with the 4QPM mask we recommend that users use the S13 objective Table 36 describes the parameters of this template Table 36 Parameters of NACO_img_acq MoveToMask P2PP label Default Description DIT NODEFAULT Detector Integration Time secs NDIT NODEFAULT Number of DITs PSF r
155. utes Guide Star Acquisition 0 75 minutes Initial Setup 2 minutes AO acquisition 5 minutes Coronographic acquisition 2 minutes Sub total 12 75 minutes Observation 2 10 6 10 0 7 9 16 27 4 5 10 0 7 27 36 minutes Total 49 minutes Overheads 84 Observation Number of AB cycles x Number of Exposures Object Only x DIT x NDIT readout overhead Number of Exposures Object Only 1 x time between frames without offsets Offset overhead Number of offset positions Sky only x DIT x NDIT readout overhead Offset overhead Table 28 Overheads Example 7 LW Coronography of a bright source Template parameters Acquisition Template NACO_img_acq MoveToMask Observation Template NACO_coro_obs_AutoChopNod Integration time minutes 20 minutes Execution time Preset 3 minutes Guide Star Acquisition 0 75 minutes Initial Setup 2 minutes AO acquisition 5 minutes Coronographic acquisition 2 minutes Sub total 12 75 minutes Observation 20 1 3 60 27 35 minutes Total 48 minutes Overheads 140 Observation Integration time minutes x 1 30 x 60 seconds Offset overhead NAOS CONICA User Manual VLEMAN ESO 14200 2761 49 Table 29 Overheads Example 8 Imaging with chopping Template parameters Acquisition Template NACO_img_acq MoveToPixel Observation Template NACO_img_obs_AutoChopNod Integration time minutes 20 minutes Execution time Preset 3 minutes Guide Star
156. ve Optics configuration can be displayed by clicking on the AO Config button in the subpanel depicted in Figure 33 An example is shown in Fig 34 LAO Configuration Figure 34 Pop up window showing an optimal configuration of the AO system You do not have to worry about these parameters but they may give you some insight into the way NAOS works From the perspective of the astronomer the most significant result of the optimization is the corresponding estimated performance in terms of image quality It is expressed quantitatively by the computed point spread function PSF and its derived quantities The PSF is returned to the user interface in FITS format It characterizes the quality of the optical beam which is provided by NAOS to CONICA and is thus logically computed at the observing wavelength and is available from the Resulting Performance area of the GUI The provided PSF is computed off axis 1 e in the direction of the target seen by CONICA The PS computes these data on 128x128 pixels One pixel corresponds to an angle of A 2D and the extracted PSF is assumed to be monochromatic To access the PSF data once the optimization has been performed click on the PSF button This pops up a window that shows the profile of the PSF along the x and y axes Figure 35 The FITS file itself can also be saved to the user s local disk for later use If you want to save the file the Save PSF button brings a file browser and allows you
157. ve by a fraction of pixel when the rotator angle changes For coronographic observations with the semi transparent mask users should take night time flats with the NACO_coro_cal_NightCalib template These night time calibrations are sigificantly better than the ones taken in the daytime because daytime calibrations are taken without the mask Daytime calibrations with the mask are not useful because they are taken with the rotator at a fixed angle and a combination of irregularities NAOS CONICA User Manual VLEMAN ESO 14200 2761 41 on the glass plate holding the mask and instrument flexure means that flats depend on the rotator angle For FP imaging we recommend that users do a scan of one of the bright argon arc lines with the NACO fpi cal Arcs template immediately after the observations 5 17 Pipelines It is our long term aim to produce pipelines that reduce NAOS CONICA data accurately At this point in time this is not the case and experienced observers will be able to do better than the pipeline Thus we recommend that users only use pipeline products as a means of quickly assessing the data For the templates supported by the pipeline currently only imaging templates are supported service ob servers will receive pipeline reduced data Visitors will have direct access to the data processed automatically on line but the data are not calibrated e g flat fielded as they are in Garching for service observations Visi tors can sav
158. we cannot say how accurate these calibrations will be Should users wish to use telluric standards of a particular spectral type they should provide the corresponding OBs and detailed instructions In this case the time executing the OBs will be charged to the user and the observatory will not observe a separate telluric standard e Spectroscopic lamp flats in all SW spectroscopic modes slits and readout modes e Spectroscopic arcs in all spectroscopic modes and slits An atlas of lines for the SW modes is avail able from the NAOS CONICA web page LW spectroscopic arcs are not supported For slitless spec troscopy arcs with the 86mas slit will be provided 28 NAOS CONICA User Manual VLEMAN ESO 14200 2761 Table 10 Spectroscopic modes The mode name consists of the objective the grism number and the order sorting filter Mode Name pectral domain Order Spatial Scale Linear dispersion o cn ns p 54_4_SJ 54_3_SH 1 37 1 84 S27_3_SH 1 37 1 72 S27_4_SH 1 37 1 84 54_2_SK S27_2_SK 54_3_SK 27_3_SK 2 60 4 20 L27 1 5E 2 60 4 10 L54_2_SL 3 02 4 20 L272_SL 3 47 4 20 12711 3 20 3 76 2 160 700 AE L27 1LP 3 50 4 10 2 27 7 60 700 L54 2 LP 3 50 4 10 1 54 127 2 LP 3 50 4 10 27 2 00 1100 1 00 1100 Light from the second order can also be seen but does not contaminate 2 SJ SH SK SHK and SL are special broad band filters for spectroscopic applications They cover a wider wavelength range than the standard J
159. with 4QPM SDI 4 and rotation In the following section the relative merits of different observing techniques with 4QPM and SDI 4 are discussed this analysis was performed by the commissioning team The tests were performed on sky on a star and a reference and the results presented in Figure 15 In this figure we compare the detection levels that can be reached with the classical no SDI coronagraphic imaging using reference subtraction or not with SDI 4 using subtraction of SDI images of the reference or not The effect of roll averaging is also studied The reference subtraction is only done on 3 4th of the data 8 images out of 11 to match the parallactic angle of the star and its reference In the figure the SDI processing solid green appears to be slightly better for the short angular separation less than 0 4 than the coronagraphic imaging using subtraction of a reference star dotted black To see the effect of the rotation we added the different images we recorded after correcting for the instrument rotation in order to add up companion signal while averaging out speckle and readout noise The effect is clearly an improvement of the detection capability especially at large angular distances dashed green The subtraction of the SDI image of the star with the SDI image of the reference star solid red was also investigated This technique is more efficient than the SDI image at angular distance shorter than 1 arcsec and is the same
160. with other IR instruments One has to deal with high and variable backgrounds and modest detector cosmetics In general the IR background particularly at longer wavelengths is higher for an IR instrument with an AO system because of the additional optics in an AO system Additionally the classical chop and nod technique which is commonly used for the LW filters in non AO systems works less well as the DM introduces back ground fluctuations that do not cancel perfectly This does not degrade L band observations but it may degrade M band observations Given the relatively small field of view of CONICA it is possible to observe in the L band without having to chop and nod However the overheads are relatively large typically 50 100 as the sky has to be sampled frequently at least once a minute and poor results can be obtained if one does not offset frequently or if the time scale for fluctuations in the L band background is short We strongly recommend that users limit themselves to the NACO_img_obs_AutoJitter template Section 6 5 2 if they choose not to use the classical chop and nod technique Users are free to choose between jittering and the more classical chop and nod style of observations for the L NB_3 74 and NB_4 05 filters Observations in the M band can only be done with chopping One of the major differences between AO and non AO systems is the pixel scale The pixel scale of CONICA can be as fine as 0 013 arc seconds which
161. y For coronagraphic applications a Lyot type coronagraph with a circular focal plane mask and an undersized pupil plane mask can be rotated into the beam of CONICA Three masks are available two opaque masks with diameters of 0 7 and 1 4 arc seconds and a semi transparent mask with a diameter of 0 7 arc seconds NAOS CONICA User Manual VLT MAN ESO 14200 2761 17 1 625 microns Figure 6 Flatfield image of the SDI mode The transmitted wavelengths are indicated Please note that on that image the mask was not centered 1 625 microns 1 625 microns Figure 7 Flatfield image of the SDI mode The transmitted wavelengths are indicated Please note that on that image the mask is not well centered However the vertical vignetting cannot be corrected for NAOS CONICA User Manual _ ___VLT MAN ESO 14200 2761 Figure 8 Flatfield image of the 4QPM_K Ks filter image of the 4QPM_K Ks filter left and of the 4QPM H H filter right 1 and of the 4QPM_H H filter right The many dust particles observed in the flats generate flat filed variations of 10 20 locally The contrast between inside and outside of the 0 7 semi transparent mask has been measured to be AKs 6 3 0 1 and AH 6 0 0 1 in Ks and H band respectively The opaque masks are held by wires and the semi transparent mask is situated on a transparent plate The available masks are listed in Table 8 More information on coronagraphy can be found at http

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