VERY LARGE TELESCOPE NaCo Calibration Plan
Contents
1. 10 NaCo Calibration Plan VLT PLA ESO 14200 2664 airmass 2 Test the possibility to take flats with pupil angle constant as the telescope is moved down LW flats are taken for the following setups imaging polarimetry with no Wollaston and coronagraphy with no masks Sky flats taken with neutral density filters Wollaston and coronagtaphic masks are not supported in SM Flats taken on Mp use a windowed detector setup Template NACO_img_cal_SkyFlats Purpose Flat fields for thermal imaging polarimetry coronagraphy Description taken at two airmass values 1 and 2 All flats taken with the VIS dichroic Observing Conditions late twilight nighttime CONICA state Online CONICA setup same as for science frames No Wollaston or HWP for Polarimetry no mask for coronagtaphy NACO State Online TCS State Online Frequency when needed for science observations Duration 10 15 minutes Pipeline recipe naco_img_twflats Procedure o Take the median of the frames taken at the same airmass o Subtract the X 1 from the X 2 extract pixel map o Extract the bad pixel map o Normalize Pipeline data products LW flats 6 6 Internal lamp flat fields Internal lamp flat fields are taken with a halogen lamp for every setup observed during the night These are daytime calibrations and consists of series of lamp on lamp of frames for every setup filter cameras detector readout mode observed at night All readout modes are supported SDI fla2. 300 1 6 5 Twilight Flat Fields There are two types of twilight flats SW and LW both used for imaging applications but also used for DI and coronagraphy The SW twilight flats can only be executed during the NaCo Calibration Plan VLT PLA ESO 14200 2664 day typically one hour before sunset the latter can be executed any time of the night twilight or not 6 5 1 SW twilight flats The amount of work required to acquire SW flats in all bands which are observed is often too much for Operations given that not more than 2 3 sequences can be acquired each day whenever is not cloudy The amount of time needed for taking SW flats for NaCo is now also not compatible with the additional needs imposed by HAWKI twilight flats NaCo at difference with HAWKI has the capability to acquire internal lamp flats It is therefore decided to considerably decrease the amount of SW sky flats taken with NaCo Experience has shown that internal flats are equally good In order to make sure that there is indeed no change in the system and sky flats and internal flats are comparable it is recommended to still observe sky flats weekly or bi weekly for BB J H Ks S27 DCR and use them to control that the ratio with the internal flat is 1 Internal flats should be taken every day for the setups observed the night before and in the same setup as the sky flats when those are taken Changes to the system that can affect the quality of the illuminatio
3. Daytime When needed Not offered now NACO_pol_cal_LampFlats Polarimetry Daytime When needed internal lamp flats NACO img cal_StandardStar ZP standard star Twilight night Daily if conditions CLR When needed NACO_spec_cal_StandardSar Telluric star Night When needed NACO_spec_cal_LampFlats Spec internal flats Daytime When needed NACO_spec_cal_arcs Spec arc frames Daytime When needed NACO_gen_tec_Linearity Detector gain Daytime Every period or after and linearity an intervention 17
4. NACO_gen_tec_Linearity Purpose measure gain linearity Description plots the transfer curve Signal vs noise using sequences of flats taken at different DITs and covering the full dynamic range of the detector Observing Conditions daytime upper lights off lower lights OK CONICA state online CONICA setup NACO State ignore TCS State ignore Frequency every six months Duration 50 minute 10 minutes per setup Pipeline recipe naco_detlin Pipeline data products gain linearity 16 NaCo Calibration Plan VLT PLA ESO 14200 2664 7 Summary The following table summarizes the list of templates the corresponding calibration the time of execution and the frequency When needed means that science observations which require the calibration were performed the previous night When requested means that it is either a VM request or a special calibration for SM programs Template Data product Time Frequency NACO all cal Darks Darks Day Daily NACO_ing_cal_ TwFlats SW Twilight flats Twilight Weekly for checks NACO_img_cal_SDITwFlats SDI twilight Twilight VM only or when flats requested NACO_img_cal_SkyFlats LW Sky flats Twilight night When needed NACO _img LampFlats Internal lamp Daytime When needed daily flats imaging if NaCo used SAM coronagraphy NACO_img_cal_SDILampFlats SDI Internal Daytime When needed lamp flats NACO_fpi_cal_LampFlats Fpi internal flats
5. and for imaging mode only calibrating everything costs too much time For example Ks S27 FNS was not calibrated A better practice is that of always matching the detector readout and dichroic AO setup to the science observations This is being implemented with this version of the calibration plan Among the non supported setups we still have imaging with NB IB and ND plus polarimetry and coronagraphy not supporting these modes goes against the spirit of the calibration plan but it may end up being too much to support Therefore those calibrations will not be routinely supported by the calibration plan but can still be performed when requested by the users and accounted for in their allocated time Frequency of calibration once a night at the beginning of the night in Broad Band BB filters with the S27 camera and or BB S13 Then when moving to a PHO program a standard star with the setup of the science OB filter camera detector setup must be observed The standard star must also be observed immediately after the science to check for stability the ZP difference between the two STD observations should be less than 0 04 in order for the science OB to be classified as A or B No standard star will be taken in THN or THK conditions When possible the standard star of the month will always be observed at the beginning of the night Only low airmass measurements are taken An historical database of zeropoint measured with NaCo is maintained o
6. of ADU as twilight deepens Generally there are 5 20 images for each filter in a twilight sequence Template NACO_img_cal_TwFlats Purpose SW sky flats Description sequence of images taken on sky during twilight Observing Conditions Clear No flats should be taken in THN conditions or worse CONICA state Online CONICA Setup S27 J H Ks DCR HD NACO State Online TCS State Ignore flats are taken at Zenith Frequency once a week Duration 30 60 minutes Pipeline recipe NACO_img_twflat It is identical to ISAAC twilight flats o Reject frames with counts above 6800 ADU Subtract a dark with the same DIT and camera optional Compute the linear regression factors on every pixel Extract the bad pixel map Normalize Issue a warning if the number of frames per filter is less than five or if the range of fluxes in the frames for any one filter is less than a factor of three Pipeline data products SW gain map bad pixel map Accuracy SN gt 100 and lt 2 illumination error O000 0 For Polarimetry CONICA Setup Filter detector camera setup as used by science No Wollaston Frequency when needed i e when polarimetric observations are done 6 5 2 LW twilight flats LW sky flats have to be done on sky since internal lamps do not work at thermal wavelengths Up until now we take three sets of flats at three different airmass The following changes are proposed with the new plan take only two sets one at zenith and the other at
7. otherwise the following guidelines for the choice of the telluric are followed Spectral Band of Star type Notes science OB J Hot B but also O and A V I should be negative IR E g BOV B5V magnitude should preferably be known H Very hot e g OOV BOV V I should be negative IR B3V magnitudes should be known K G or B Late B e g B5 6 may E g GOV G5V BOV B5V contain strong Bracket lines H K G E g GOV G5V Lp B O G and A K for N a amp Mp M bands The recommended telluric star IR magnitudes and corresponding V magnitudes for a G2V star as a function of instrument mode for NACO are listed below the last column lists the recommended flux level for the telluric star spectrum in the RTD Instrument IR Approx V mag range Flux range in the Mode dichroic Magnitude for G2V star RTD ADUs SW VIS K 7 5 10 9 12 Depends on selected SW K H 7 5 10 9 12 Read out mode SW N20C80 K 7 9 5 9 11 DCR lt 10000 SW N90C10 K 5 7 7 9 FNS lt 5000 LW VIS L 5 7 7 9 LW JHK L 5 7 7 9 14 NaCo Calibration Plan VLT PLA ESO 14200 2664 Template NACO_spec_cal_StandardStar Purpose observe a telluric standard calibrator Description Nighttime calibrations taken immediately before or after the science OB The star is typically chosen with airmass similar to the one of the science at mid exposure 0 1 Observing Conditions same as for the scien
8. Director of the LPO for 2008 The calibrations covered by this revision include daytime calibrations e g darks internal lamp flats arcs etc nighttime calibrations photometric standards telluric standards night time internal flats sky flats Other miscellaneous calibrations instrumental aberrations detector performance parameters etc will be added later on In particular the detector characterization is taken care of in the frame of the detector monitoring project 6 The revision addressed the following points 1 Reduction of redundancy a Are we over calibrating b Are we taking calibrations that are not useful 2 Completeness check a Are we taking all the necessary calibrations b Are all observing modes characterized properly 3 Quality of calibrations a Can we improve the quality of the calibrations we take The primary scope of the revision was to reduce the time spent on calibrations while keeping or increasing their overall quality and completeness The revision of the NaCo Calibration plan was done in two steps a meeting in Santiago which produced the first draft of this document and a mini review in Garching which discussed the document suggested improvements and changes NaCo Calibration Plan VLT PLA ESO 14200 2664 As a result of this revision the new NaCo calibration plan document has been issued Since there are significant changes on the type and the frequency at which some calibrations are ta
9. ES EUROPEAN SOUTHERN OBSERVATORY Organisation Europ enne pour des Recherches Astronomiques dans I H misph re Austral Europ ische Organisation f r astronomische Forschung in der s dlichen Hemisphare VERY LARGE TELESCOPE NaCo Calibration Plan Doc No VLT PLA ESO 14200 2664 Issue 2 ver 84 Date 30 10 2008 Prepared P Amico C Lidman E Pompei Name Date Signature Approved C Dumas Name Date Signature Released A Kaufer Name Date Signature NaCo Calibration Plan VLT PLA ESO 14200 2664 CHANGE RECORD ISSUE DATE SECTION PARA REASON INITIATION AFFECTED DOCUMENT REMARKS 2008 release NaCo Calibration Plan VLT PLA ESO 14200 2664 TABLE OF CONTENTS Nn L R MUNN 7 Scope List of Abbreviations amp Acronyms List of Applicable Documents Introduction 2008 Calibration Plan revision Calibration Plan 6 1 Introduction 6 2 Template Naming Convention 6 3 Dark frames 6 4 Other dark frames 6 5 Twilight Flat Fields 6 5 1 SW twilight flats ovo Ge A ANI A A A L L P avr 6 5 2 LW twilight flats 6 6 Internal lamp flat fields 6 6 1 Imaging Lamp flats 6 6 2 Polarimetric lamp flats 6 6 3 Spectroscopic lamp flats 6 7 Wavelength Calibrations 6 8 Photometry Zeropoints 6 9 Telluric Standard Stars 6 10 Other nighttime calibrations 6 10 1 Nighttime spectroscopic arcs and flat fields 6 10 2 Nighttime coronagraphic SDI and SDI 4 flat fields 6 10 3 PSF measur
10. Project 6 NaCo Calibration Plan VLT PLA ESO 14200 2664 The determination of complex and more exotic calibrations such as instrumental aberrations distortion maps instrumental polarization etc are not part of the calibration plan but are carried out as part of a maintenance activities In 2008 two Nato calibration proposals have been granted observing time these proposals aim at calibrating specific aspects of the instruments e g accurate plate scales and are usually submitted by ESO s users who are willing to collaborate with the observatory staff to provide expert advice and help The findings of these programs are immediately shared with the community via the manuals and the instrument web pages Users interested in submitting a calibration proposal or more generally in sharing some of their results are invited to contact the NaCo Instrument Scientist at naco eso org Users are also invited to look at the NaCo Contributed Papers Library 7 for references to interesting papers on NaCo and to submit their own entries email naco eso org that is papers which discuss novel data reduction and calibration techniques which can be of interest to the community Additional information about calibrations for the different instrument modes can be found in the NAOS CONICA user manual 5 2008 Calibration Plan revision The revision of the calibration plan for each instrument in Paranal was one of the goals and objectives set by the
11. Very Large Telescope VM Visitor Mode WES Wave Front Sensor ZP ZetoPoint NaCo Calibration Plan VLT PLA ESO 14200 2664 3 List of Applicable Documents 1 The NaCo Calibration Plan VLT PLA ESO 14200 2664 N Ageorges C Lidman Issue 80 March 03 2007 2 Description of observing modes www eso org sci facilities paranal instruments naco inst 3 ZPs in Paranal why and what to do with Draft E Mason May 2008 4 NaCo Quality control pages http www eso org observing dfo quality index_naco html 5 Reference calibration frames www eso org observing quality ALL ref_framesref_naco html 6 Telluric Stars 101 P Amico and C Lidman ESO Internal Document Release Nov 2007 7 The Detector Monitoring Project P Amico L Vanzi C Lidman VLT PLA ESO 10400 4387 Issue 2 2 Date 20 07 2008 Also presented in the Proceedings of The 2007 ESO Instrument Calibration Workshop Garching Germany 2007 Springer Verlag 8 The NaCo Contributed Papers library http www eso org sci facilities paranal instruments naco tools library html 9 The NaCo pipeline Manual ftp ftp eso org pub dfs pipelines naco naco pipeline manual 1 1 pdf 4 Introduction The primary goal of the calibration plan is to provide the NaCo users with those calibration frames such as darks flat fields arcs zero points and telluric reference observations which enable the effective removal of instrumental and atmospheric signatur
12. age of the mask SDI SDI 4 These frames are taken at no cost to the user However if more sets of frames are needed users should use the template NACO_coro_cal_NightCalib to acquire more flat on flat off pairs The template should be executed immediately after the science OB to ensure that the mask is in the same position Users are cautioned that for very long OBs instrumental flexures may slightly shift the optical element 6 10 3 PSF measurements for SDI 4 and 4QPM masks The acquisition templates for SDI 4 NACO_img_acq_SDIMoveToMask and for coronagraphy NACO_img_acq_MoveToMask when used with 4QPM_H or 4QPM_K allow taking a PSF image of the object off mask plus corresponding sky The images can be used for PSF determination PSF data taking is currently optional and users interested in these images should mention it in their README files The images are taken at no time cost to the users 6 10 4 Nighttime FP arcs Since we have observed drifts of about 1 nm in the setting of the FP over a 24 hour 15 NaCo Calibration Plan VLT PLA ESO 14200 2664 period it is mandatory that users attach the NACO fpi cal Arcs template at the beginning of every OB that uses the FP The purpose of this template is to determine the transformation between x y detector coordinates and z FP plate distance and x y versus A Additional details are given in the NACO User Manual Currently the FP is not offered for technical reasons 6 11 Detector Cal
13. ce target CONICA state online CONICA setup same as for the science targets For LGS OBs a NGS telluric is observed NACO State Online TCS State online tracking Frequency one or two per science target Duration 15 minutes including acquisition Pipeline recipe naco_spc_combine Pipeline data products combined wavelength calibrated spectrum 6 10 Other nighttime calibrations 6 10 1 Nighttime spectroscopic arcs and flat fields Users can choose to take nighttime spectroscopic arcs and flat fields Usually these calibrations are not required if you wish to do spectro photometry to an accuracy of 5 or less If the option to take lamp flats is selected n pairs of frames where n is a number between one and three with the lamp on and off will be taken Likewise if the option to do arcs is selected one frame with the arc lamp on and one frame with the arc lamp off will be taken Alternatively one can select to do both lamp flats and arcs in which case n 1 pairs of frames will be taken 6 10 2 Nighttime coronagraphic SDI and SDI 4 flat fields Optical elements on a glass substrate c_0 7_Sep_10 4QPM_H 4QPM_K SDI SDI 4 cannot be properly flat fielded using daytime flats The repositioning of the optical element is not accurate enough to produce a good flat that can be used to remove dirt and particles from the substrate For this reason the new acquisition templates for these modes acquire one flat on and one flat off im
14. ements for SDI 4 and 4QPM masks 6 10 4 Nighttime FP arcs 6 11 Detector Calibrations Summary NaCo Calibration Plan VLT PLA ESO 14200 2664 1 Scope This document replaces entirely the VLT PLA ESO 14200 2664 Issue 80 after a revision of the calibration plan was set as observatory wide goal for 2008 The new version will be probably implemented for p83 or p84 For P82 the old calibration plan remains the reference 2 List of Abbreviations amp Acronyms This document employs several abbreviations and acronyms to refer concisely to an item after it has been introduced The following list is aimed to help the reader in recalling the extended meaning of each short expression 4QPM 4 Quadrants Phase Mask Comes in two versions 4QPM_H and 4QPM_K BB Broad Band CLR Clear weather conditions DCR Double Correlated Readout DIT Detector Integration Time FNS Fowler N Sampling FP Fabry Perot HWP Half Wave Plate IB Intermediate Band LPO La Silla Paranal Observatory LW Long Wavelength NaCo NAOS CONICA NB Narrow Band NDIT Number of Die OB Observing Block PHO Photometric QC Quality Control RMS Root Mean Square RON Read Out Noise SDI SDI Simultaneous Differential Imager SDI is the new larger FoV SDI SDI 4 SDI combined with coronagraphy with 4QPM_H SM Service Mode SN Signal to Noise STD Standard star SW Short Wavelength THK Thick clouds THN Thin clouds UT4 Unit Telescope 4 a k a Yepun VLT
15. es from their science files NaCo is a very versatile instrument Dichroics masks filters polarizers grisms cameras and other more exotic elements can be combined together to provide a large number of observing configurations For imaging in the broad band H band filter alone one could in principle choose among 24 different configurations 4 NAOS dichroics 3 CONICA cameras and two readout modes and this does not include the possibility of polarimetric and coronagtaphic configurations Given the high number of possible scientific setups the scope of the NaCo calibration plan had to be limited to the most popular modes which provide also a meaningful set of interesting setups for instrument performance monitoring and trending Less popular modes or custom made observations are usually calibrated on an irregular basis typically when the corresponding science requires it e g standard stars for NB filters and or whether the users requests special calibrations to be carried on We remind users that non standard calibrations usually are approved only in VM or at least require a waver Time needed at night for special calibrations not included in the calibration plan will be charged to the corresponding observing program Other important parameters such as the detector characteristics gain linearity periodic noise etc are now monitored on a regular basis by the observatory staff following the guidelines outlined in the Detector Monitoring
16. frames is therefore not recommended Darks for cube mode science data are taken with the correct windowing setup Le hardware windowing even for the full frame option but are however single frames not cubes Template NACO_all_cal_Darks Purpose Remove zero level offset measure RON measure hot pixels Description Dark frames are obtained at the end of the night for each detector setting readout mode detector mode DIT and camera window type HW or SW that was used during the previous night Three darks are taken for each setting NDIT is set according to the formula if DIT lt 10 NDIT INT 10 DIT 1 if DIT gt 10 NDIT 1 Observing Conditions daytime upper lights off lower lights OK CONICA state dark position Le with two non overlapping NB filters in the optical path NACO State Ignore TCS State Ignore Frequency once every three days Duration up to 1 hour Pipeline recipe naco_img_dark Pipeline data products o median frames with the same DIT detector mode detector window readout mode and camera o compute RON and median values produce hot cold and deviant pixel maps Accuracy limited by thermal leaks 6 4 Other dark frames For monitoring purposes by QC the following set of 3 darks per setup should be taken daily as the first calibration taken in the morning to avoid frame contamination due to detector persistence problems Detector setup DIT NDIT DCR HD 0 5 100 FNS HS 1 792 10 FNS HS
17. ibrations Detector calibrations performed regularly on NaCo include noise dark current hot and cold pixels and are published on the QC web pages An historical database trend plots and statistical analysis are available in addition to the daily measurements Measurement of noise for DCR FNS and UCR http www eso org observing dfo quality NACO reports HEALTH trend_ report RON HC html Measurement of dark current http www eso org observing dfo quality NACO reports HEALTH trend_ report DARK HC html Measurement of hot cold pixels http www eso org observing dfo quality NACO reports HEALTH trend_ report HOTCOLDPIX HC ht ml As of P82 a new detector linearity template and corresponding pipeline recipe was released It uses the method of the transfer curve to measure gain linearity levels saturation and noise The observing template is run in daytime and collects a series o pairs of flat frames that cover the full dynamic range of the detector in a particular readout mode Darks with the same DIT as the flats are also collected The supported setups are Readout mode Detector mode Instrument mode Double correlated readout High Dynamic HD All SW modes DCR Fowler N Sampling FNS High Sensitivity HS All SW modes Uncorrelated UCR High Dynamic HD NB thermal imaging Uncorrelated UCR HighWellDepth HWD Lp imaging Uncorrelated UCR HighBackeround HB Mp imaging Template
18. ic describes the main function of the template 6 3 Dark frames Dark frames in CONICA are contaminated by thermal leaks which vary with a timescale of some hours up to 1 day Thermal leaks are best seen on long darks see for instance in 5 the DCR HD darks with DIT gt 30 secs but present at all DITs these leaks show up as brighter stripes in the frames These stripes vary in intensity a feature best seen in difference frame A characterization of the phenomenon is being conducted and depending on the results darks frames may be declared not useful for science unless taken within a safe timeframe Dark frames as well as science frames show noise patterns at different frequencies 50 12 10 Hz These patterns can be easily removed in all frames especially in cube mode with the usual method of measuring the median value row by row and subtract it from the row itself an alternative solution would be that of removing the offending frequency in NaCo Calibration Plan VLT PLA ESO 14200 2664 Fourier space identify the relevant wave vectors in the power spectrum masking all other wave vectors inverse transforming and subtracting Additional noise patterns can also be seen as a function of the rotator angle Since darks are taken with the rotator at 0 the patterns may differ from what is seen in the science frames For this reason and for the variability of the thermal leaks the practice of dark subtraction from science
19. ken users are invited to read this document carefully before submitting their proposals 6 Calibration Plan 6 1 Introduction This section gives an overview on all calibrations that are carried out at regular intervals in order to guarantee the calibration of scientific data Such set of calibrations is the minimum necessary to ensure a good calibration of NaCo s data Users who have specific requirements such as for instance high S N or higher accuracy ate requested to fill in the Special Calibrations Section in the proposal form Once approved a description of the special calibrations should be added in the README file Data products resulting from the calibration observations are archived and available for science calibration quality control and monitoring of instrument performance 4 A detailed description of the data reduction recipes is given in 9 A summary table is available in section 7 6 2 Template Naming Convention Observing templates are named following the convention NACO_mode_type_mnemonic where Oo mode is img for imaging spec for grism spectroscopy pol for polarimetry coro for coronagtaphy fpi for FP imaging sdi for imaging with SDI sdi4 for sdi combined with phase masking coronagraphy sam for sparse aperture masking and all for templates applying to all modes O wpe is acq for acquisition obs for observation cal for calibration and tec for maintenance gen for general applications O mnemon
20. lats with the same setup filter camera detector no mask are enough For the other coronagraphic masks internal flats will be taken mostly at night 5 SDI flats on sky can be also eliminated and replaced by internal flats 6 Twilight flats with the neutral density filters the Wollaston the Fabry Perot FPI are not supported in SM In visitor mode o Twilight flats can be taken upon request also with other readout modes as DCR NaCo Calibration Plan VLT PLA ESO 14200 2664 but visitors should note that some combinations of filter objective and readout mode may be very difficult to do Since this internal lamp flat is not possible with the half wave plate upon request in visitor mode twilight flats can be taken with the half wave plate in the beam o Twilight flats with the SDI Simultaneous Differential Imager are supported with a special template called NACO_img_cal_SDITwFlats These flats are taken with the complete SDI set up i e special SDI field mask SDI double Wollaston H broad band filter and SDI objective present in the light path The count level in twilight flats taken in Double_RdRstRd and with DITs shorter than 60 seconds starts with an average count level of 6000 ADU and this decreases with deepening twilight to a few hundred ADUs The count level in twilight flats taken in FowlerNsamp or for flats with DITs greater than 60 seconds start with an average count level of 2000 ADUs and decrease to several tens
21. n pattern for internal flats are a The telescope pupil gets misaligned b The integrating sphere is moved intentionally or bumped into We therefore propose the following strategy Test 1 Use the periodic BB sky flats to compare with internal lamps These tests will be assigned to QC Test 2 Once a week take an image of the pupil imager to see if the pupil is evenly illuminated In the long run it is hoped that the frequency of lamp flats can be lowered i e once every few days instead of every day A template for this test has to be developed Other issues to be considered 1 Stability of the flats To be checked by QC using historical data A first QC report confirms that flats have bee very stable 2 Flats with different dichroics Currently we take flats with the VIS dichroic We think there is no need to use other dichroics because the amount of light changes but pattern does not change within 1 This should be confirmed re tested 3 Polarimetric flats need to be taken on sky since internal flats make use of an additional mirror which changes the polarization However there is no need to put the polarizer in the beam since flats are used to remove the detector signature and standard flats can be taken with the desired setup filter detector camera 4 Coronagraphic flats for C 1 4 and C 0 7 are currently not taken on sky for SM They are taken in VM but we think they are not useful Normal internal f
22. n the NACO QC web pages http www eso org observing dfo quality NACO reports HEALTH trend_ report ZEROP HC html Template NACO_img_cal_StandardStar Purpose measure zero points Description a standard star taken from a selected set is observed in close loop with the same AO setup WFS dichroic as the science that needs to be calibrated The star is imaged at the center and in the four quadrants of the array 13 NaCo Calibration Plan VLT PLA ESO 14200 2664 6 9 Observing Conditions at night CLR or PHO conditions CONICA state online CONICA setup imaging same filter camera and detector setups as the science NACO State online TCS State online tracking Frequency at least once a night bracketing science observations if condition PHO is requested once if CLR requested Duration 10 20 minutes Pipeline recipe naco_img_zpoint Pipeline data products o Subtract images in pair and divide by the flat o Perform aperture photometry of the standard star at five positions o Calculate mean zeropoint and associated error RMS o Measure Strehl ratio Accuracy lt 5 on zeropoints and Strehl ratio Telluric Standard Stars The new guidelines for the selection of the telluric standard and the airmass difference constraint have been published in 6 The telluric calibrator is taken immediately after or before the scientific observations at the same airmass the scientific target had mid exposure 0 1 Unless requested
23. p on frames o Median combination of all lamp off frames o Subtract lamp off from lamp on o Normalize Pipeline data products lamp flats frames for imaging SAM coronagraphy Accuracy S N gt 100 lt 5 across the detector 6 6 2 Polarimetric lamp flats These flats have been discontinued The additional mirror inserted in the light path changes he level of polarization For polarimetry sky flats without the Wollaston are taken in SM See section 6 5 for more details 6 6 3 Spectroscopic lamp flats Template NACO_spec_cal_LampFlats Purpose take spectroscopic flat fields for calibration of pixel to pixel variations Description spectroscopic lamp flat fields are taken as a daytime calibration using the halogen lamp in CONICA for the spectroscopic setups used for science at night Three lamp on and three lam off frames are taken for each setup Observing Conditions daytime calibrations upper lights off lower lights OK CONICA state online lamp mirror inserted CONICA setup same slit spectroscopic setup and detector setup as for the science frames NACO State ignore TCS State ignore Frequency within three days from the observing run Duration depending on setups Pipeline recipe naco_spc_lampflats Pipeline data products spectroscopic lamp flats Accuracy S N gt 100 lt 5 across the spatial axis 6 7 Wavelength Calibrations Currently an Argon pen ray lamp is used for spectroscopic arcs A preliminary report
24. ts are supported with a special template NACO_img_cal_SDILampFilats These flats are taken with the full SDI setup field mask Wollaston H filter and SDI camera Lamp flats with the FP are also supported by means of the NaCO_fpi_cal_LampFlats which takes images with a setup matching the science targets IB filters FP setting and detector readout mode Currently the FP is not offered 6 6 1 Imaging Lamp flats The setups covered by imaging lamp flats are o Imaging o SAM without the mask inserted o Coronagraphy without the mask inserted Lamp flats with neutral density filters are not supported LW flats are not possible with the halogen lamp An additional lamp flat measurement is taken daily by QC to check the stability of the halogen lamp flats this measurement is taken with a fixed setup i e S27 J imaging One lamp on lamp off pair is enough 11 NaCo Calibration Plan VLT PLA ESO 14200 2664 Template NACO_img_cal_LampFlats Purpose take imaging flat fields with the internal halogen lamp Description Observing Conditions daytime upper lights off lower lights OK CONICA state online calibration mirror inserted CONICA setup matching filter camera and detector setup excluding windowing NACO State ignore TCS State ignore Frequency whenever corresponding science setups observed Duration depending on the number of setups Pipeline recipe naco_img_lampflat The recipe does the following o Median combination of all lam
25. which should be confirmed recommends replacing with a Xe lamp Ar and Xe together cannot be used given the low resolution of NaCo the lines overlap too much Xe is better for LW which is currently no supported since there are no Ar lines above 2 5 microns It is panned to have the Xe lamp installed in the near future LW setups are not supported For slitless spectroscopy arcs with the 86 mas slit will be 12 NaCo Calibration Plan VLT PLA ESO 14200 2664 provided Template NACO_spec_cal_Arcs Purpose arc lamps for wavelength calibration Description Daytime calibration for the spectroscopic science setups observed the previous night One lamp on and one lamp of are taken for each setup Observing Conditions daytime upper lights off lower lights OK CONICA state online lamp mirror inserted CONICA setup same setups as for the science filter spectroscopic order NACO State ignore TCS State ignore Frequency within three days of the observing run Duration depending on the number of setups Pipeline recipe naco_spc_wavecal o Subtract frame off from frame on o Determine wavelength solution Pipeline data products 2 D wavelength solution Accuracy 5 pixels relative 2 pixels absolute 6 8 Photometry Zeropoints Refer to 3 for details on the new policy for Standard STD stars proposed for all imaging capable instruments on Paranal Up until now very few combinations of filter camera detector dichroic were supported
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