OmegaCAM Templates Manual
Contents
1. Parameter Range Default P2PP Label Entry DETI WINI UITI 0 43200 1 Exposure time s T TEL TARG ALPHA 0 240000 NODEFAULT Right Ascension T TEL TARG DELTA 9000000 900000 NODEFAULT Declination T TEL TARG EQUINOX 2000 3000 2000 Equinox T TEL ROT OFFANGLE 270 0 270 0 0 Rotator offset angle deg T TEL AG START T Acquire guide star T TEL GS1 ALPHA 0 240000 0 RA of 1 guide star T TEL GSI DELTA 9000000 900000 0 DEC of 1 guide star T TEL GS1 MAG 0 25 12 Magnitude of 1 guide star T TEL GS2 ALPHA 0 240000 0 RA of 2 guide star T TEL GS2 DELTA 900000 900000 0 DEC of 2 guide star T TEL GS2 MAG 0 25 12 Magnitude of 2 guide star T TEL ADC TYPE NONE NONE ADC Setting T COORD INS FILT NAME See Table 1 NODEFAULT Filter OCH AO START TE T Start autoguiding T OCS IA START TF T Start Image Analysis T Hidden parameters Parameter Range Value Function Entry TEL TARG ADDVELALPHA 15 15 0 Additional Velocity RA arcsec s T TEL TARG ADDVELDELTA 15 15 0 Additional Velocity DEC arcsec s T TEL AO TYPE AO NOONE AO NOONE DoaONECAL correction in preset T AO ONE 3 3 OMEGACAM img cal bias Acquire N bias exposures with opaque filter in optical path and shutter closed Integration time is zero Parameter Range Default P2PP Label Entry SEQ NEXPO 100 1 Number of exposures T Hidden parameters Parameter Range Value Func2. 5 EXPLANATIONS OF THE P2PP ENTRY FIELDS 21 5 1 User defined P2PP entry fields DET keywords 21 5 2 User defined P2PP entry fields SEQ keywords 21 5 3 User defined P2PP entry fields TEL keywords 21 5 4 User defined P2PP entry fields INS keywords 22 5 5 User defined P2PP entry fields OCS keywords 22 OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 6 of 24 1 INTRODUCTION 1 1 Scope All observations with the VST are carried out with observing blocks OBs OBs are prepared with the phase 2 proposal preparation software P2PP With P2PP the mode specific observation templates will be selected by the users and the parameter fields keywords are set to the user specified values The OmegaCAM Templates Manual describes the templates and keyword available for OmegaCAM 1 2 Applicable Documents The following documents of the exact issue shown form a part of this document to the extent specified herein In the event of conflict between the documents referenced herein and the contents of this document the contents of this document shall be considered as a superseding requirement Reference Document Number Issue Date AD1 INS SPE ESO 23100 0002 1 0 30 10 2001 OmegaCAM Technical Specifications AD2 VST SPE OCM 23100 3061 30 10 2001 OmegaCAM INS User Requirements AD3 VLT MAN ESO 17240 2240 31 03 2004 INS Common Software for Templates 1 3 Ref
3. OmegaCAM Templates Manual SEQ NEXPO 1 100 VST MAN OCM 23100 3111 1 4 05 09 2011 15 of 24 Number of exposures 3 10 OMEGACAM img cal_shutter Same as OMEGACM img cal domeflat with N 4 and exposure times 10 0 0 1 0 1 10 0 s Used to verify homogeneity in the exposure time over the scientific mosaic Parameter Range Default P2PP Label Entry DET1 WIN1 UIT1 0 43200 10 0 0 1 Exposure time s T 0 1 10 0 INS FILT NAME See Table 1 NODEFAULT Filter INS LAMP SET Set 1 Set 2 1 Calibration lamps T default non default Hidden parameters Parameter Range Value Function Entry SEQ NEXPO 1 100 4 Number of exposures T 3 11 OMEGACAM img cal_skyflat Acquire N sky twilight flats through a given filter Exposure time is computed automatically on the basis of the requested exposure level Exposures are jittered with the same pattern as in OMI EGACAM img obs jitter Parameter Range Default P2PP Label Entry DET EXPLEVEL 1 55000 20000 Requested intensity level ADU T SEQ NEXPO 1 100 1 Number of exposures T TEL TARG OFFSETSIZE 0 5 10 1 Step size in jitter offset patterns T arcsecs INS FILT NAME See Table 1 NODEFAULT Filter 3 12 img cal zp Same as stare with N 1 Used for photometric calibration of zero point for the key or user bands Parameter Range Default P2PP Label Entry DET1 W
4. MAG RIX OCAM PAE 3111 TSZ 08 Label with units where applicable RIX OCAM PAE 3111 DBA 02 NODEFAULT for exposure time RIX OCAM PAE 3111 DBA 01 Label with units where applicable RIX OCAM PAE 3111 DBA 02 Label with units where applicable RIX OCAM PAE 3111 DBA 02 Max exposure level 55 000 ADUs RIX OCAM PAE 3111 DBA 01 Label with units where applicable RIX OCAM PAE 3111 DBA 02 Changed pattern number to label RIX OCAM PAE 3111 DBA 09 b Label with units where applicable RIX OCAM PAE 3111 DBA 02 Label with units where applicable RIX OCAM PAE 3111 DBA 02 Explanation expanded RIX OCAM PAE 3111 DBA 10 Label with units where applicable RIX OCAM PAE 3111 DBA 02 Label with units where applicable RIX OCAM PAE 3111 DBA 02 Corrected list of filters RIX OCAM PAE 3111 DBA 11 Issue for PAE applied corrections as per RIXes received see VST TRE ESO 23100 0040 Inserted list of applicable and reference documents RIX OCAM PAE2 3111 ALO 02 Removed acronyms not related to this document RIX OCAM PAE2 3111 ALO 03 Added new acronyms Subsection added Offsetting Modes and Observing Strategies Written These sections were empty in the previous releases Added yet other physical units in labels where applicable RIX OCAM PAE 3111 DBA 02 Changed range for ADC Setting RIX OCAM PAE2 3080 DBA 01e Changed Diff RA DEC to Additional Velocity RA DEC arcsec s Upper limit for TEL TARG DELTA not under our control set to 900
5. calibration templates but no acquisition templates Besides this constraint sets CS and scheduling information are requested in particular for the preparation of service mode observations The target information and the constraint sets are not described below since they are general for all instruments and their description can be found in the P2PP manual RD8 Observation Description OD this defines the sequence of setups and exposures for scientific or calibration purposes It consists of one or more templates and the respective keywords If several templates are included their execution follows the sequence in the list Several OBs can be organized into groups concatenations or time links See the P2PP for surveys User Manual RD8 for more information 2 2 OmegaCAM Templates Acquisition Science and Calibration 2 2 1 OmegaCAM Observing Modes OmegaCAM defines one observing mode only imaging acronym img 2 2 2 Offsetting Modes and Observing Strategies Scientific observations with OmegaCAM are performed using templates that implement one of four Offsetting Modes STARE DITHER JITTER or OFFSET They differ in the kind of offsets that are used between exposures and in the final data product Observing Strategies on the other hand extend beyond templates and OBs They can relate to how fields are laid out during observation preparation and employ one of the basic Offsetting Modes defined above They can define additional instr
6. temperature dependent focus correction For the requested number of exposures 3 1 Check that if enabled AG and IA are setup correctly 3 2 Start scientific exposure 3 3 Start AG and IA loop 3 4 A few seconds before the end of the exposure stop AG and IA loop LA 3 5 Wait for exposure to finish shutter is closed and readout from scientific mosaic to start 3 6 Setup next exposure exposure time and filter name 3 7 Apply filter and if enabled temperature dependent focus correction 3 8 Wait until readout has finished and data from the FIERAs has been written to disk 3 9 Start asynchronous i e parallel merging of data products in final FITS file to be archived 3 10 Go to point 3 1 4 Wait for all acquired data to be merged in final files and archived Note that step 3 6 is performed even if in the stare template it is possible to specify one filter and exposure time only This happens because the exposure is actually performed through library code which is general enough to allow every exposure to have different setups The execution of setup in step 3 6 doesn t introduce any significant overhead since the control software takes no actions for those setup parameters that do not change since the previous setup command e g requesting a filter that is already in the optical path doesn t cause a filter exchange to happen The template code is shared by the OMEGACAM img obs stare and OMEGACAM img cal zp templates F
7. 0 10 10 Figure 2 Relative exposure level over the field in 5 point diag dither pattern From left to right full field region near center of the field region near a large inter CCD gap The second pattern starext is designed to cover the field as uniformly as possible with the constraint that a small area is to be left unexposed This can be used to keep a bright star off the CCDs and hence reduce stray reflections Because of this extra constraint this pattern produces a less uniform exposure over the field than the diag pattern The pattern is basically a rotated square grid of four pointings plus the central pointing It is illustrated in Figure 3 Starext would normally be used in conjunction with the movetogap acquisition template to position the bright star at the intersection of row and column gaps Figure 3 The starext pointing pattern The five dots show where a bright star is placed always in between the shaded CCD pixels The small box around the star whose size corresponds to how close the star gets to the pixels is left unexposed by the pattern If N 5 the pattern is repeated but with the addition of progressively larger diagonal offsets of 1 1 1 1 2 2 2 2 arcsec etc These decrease the size of the unexposed area by a corresponding amount The starext pattern is illustrated in Figure 4 It covers the field quite uniformly while keeping 14 smal
8. 000 RIX OCAM PAE 3111 DBA 05 Corrected range for INS LAMP SET RIX OCAM PAE2 3080 DBA 01 Section added description of jitter and dither patterns RIX OCAM PAE2 3111 FSE 08 Section added explanation of P2PP entry fields Removed OCAM img cal cte template merged OCAM img obs zpkey and OCAM img obs zpuser templates renamed OC AM img obs in mg cal mont 2 5 2 5 4 Added text for the OCAM img cal zp template Updated after Commissioning 2 Many gt OMEGACAM 1 1 VLT gt VST 1 3 Updated some documents numbers and issue dates 2 1 Corrected typo Updated definition of Observation Description OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 3 of 24 2 2 2 Updated list of Offsetting Modes 2 3 1 Added warning about possibility that acquisition procedure can change Removed references to telescope guide probe Specified that IA acquisition may include a few corrections and that IA AO are not performed in SSOs observations 2 3 2 Removed references to telescope guide probe 2 4 1 Specified that AG and IA loops are stopped before shutter is closed 2 4 2 Specified that AG and IA loops are stopped before shutter is closed 2 5 1 Specified that bias and dark are carried out by observatory staff 2 5 2 Specified that flats are carried out by observatory staff 2 5 3 Specified that sky flats are carried out by observatory staff and that offs
9. EUROPEAN SOUTHERN OBSERVATORY Organisation Europ enne pour des Recherches Astronomiques dans l H misph re Austral Europ ische Organisation f r astronomische Forschung in der s dlichen Hemisphire VLT PROGRAMME VLT Software OmegaCAM Instrument Software OmegaCAM Templates Manual Doc No VST MAN OCM 23100 3111 Issue 1 4 Date 05 09 2011 Name Date Prepared A Baruffolo Kuijken 05 09 2011 Name Date Se GR Approved Muschielok 05 09 2011 OW W Name Date Signature Released B Muschielok 05 09 2011 7 y IA SSUE DATE 01 02 04 2004 13 05 2004 15 11 2004 OmegaCAM Instrument Software OmegaCAM Templates Manual SECTION PAGE AFFECTED VST MAN OCM 23100 3111 1 4 05 09 2011 2 of 24 CHANGE RECORD REASON INITIATION DOCUMENTS REMARKS First issue for PPAE See details below 3 1 3 4 3 5 3 7 3 9 3 11 3 12 3 14 3 7 3 15 0 3 12 3 18 Table 1 See details below 1 2 1 3 1 4 2 2 2 2 3 2 42 5 3 3 1 0 0 3 4 3 5 3 6 3 7 3 10 Second issue for PPAE after corrections according to RIXes received Entry for ROT OFFANGLE changed to P units added ranges for TEL TARG ALPHA and DELTA RIX OCAM PAE 3111 DBA 03 added keywords TEL GS1 ALPHA DELTA MAG RIX OCAM PAE 3111 TSZ 08 Label with units where applicable RIX OCAM PAE 3111 DBA 02 Upper limit for TEL TARG DELTA set to 450000 RIX OCAM PAE 3111 DBA 05 added keywords TEL GSI ALPHA DELTA
10. G and IA loop 3 5 Offset telescope and in parallel setup next exposure exposure time 3 6 If enabled apply temperature dependent focus correction 3 7 Wait until readout has finished and data from the FIERAs has been written to disk 3 8 Go to point 3 1 4 Offset telescope back to preset position 5 Wait for all acquired data to be merged in final files and archived 2 5 4 Photometric Zero Point Calibration Executes one exposure using the obs stare template with a user selected filter OmegaCAM Instrument Software S OmegaCAM Templates Manual 3 Templates Description The following sections list in tabular form for each template 1 The template keywords The value range for the keywords The default values The P2PP name of the keyword entry fields The selection and entry option for the keyword Keyword order in the tables below the keywords are ordered as follows 1 DET keywords parameters for CCD setup and exposure time 2 SEQ keywords Sequence keywords for series of exposures etc 3 TEL keywords parameters for telescope preset guiding offsets etc 4 INS keywords parameters for instrument setup VST MAN OCM 23100 3111 1 4 05 09 2011 12 of 24 Selection and entry options for the keywords different selection and entry options exist for the actual value of the keyword entered by the user in the template form e Single value in Range column keyword parameter is fixed No user m
11. IN1 UIT1 0 43200 1 Exposure time s T INS FILT NAME See Table 1 NODEFAULT Filter P OCS STRTG NODEFAULT Observing strategy T Hidden parameters Parameter Range Value Function Entry SEQ NEXPO 100 1 Number of exposures T 3 13 OMEGACAM img obs dither Observe with N pointings default 5 maximum TBD in the sky with offsets maximum gap between detectors 400 pixels between exposures Target acquired with sidereal tracking only Dither patterns are described in detail in Sect 4 2 Parameter Range Default P2PP Label Entry DETI WINI UITI 0 43200 NODEFAULT Exposure time s T SEQ NEXPO 100 1 Number of exposures T TEL TARG OFFSETSIZEX 0 999 25 Step size in x arcsec T TEL TARG OFFSETSIZEY 0 999 85 Step size in y arcsec T TEL TARG DX 0 0 25 8 Unexposed gap size in x arcsec T TEL TARG DY 0 0 85 8 Unexposed gap size in y arcsec T TEL TARG PATTERN diag starext diag Dither pattern name P INS FILT NAME See Table 1 NODEFAULT Filter OCS STRTG NODEFAULT Observing strategy P OmegaCAM Instrument Software S OmegaCAM Templates Manual 3 14 OMEGACAM img obs jitter Observe with N pointings 2 20 in the sky with small offsets 5 pixels between exposures Target acquired with sidereal tracking only Jitter patterns are described in detail in Sect 4 1 VST MAN OCM 23100 3111 1 4 05 09 2011 16 of 24 Parameter Range Defa
12. NODEFAULT Right Ascension T TEL TARG DELTA 900000 900000 NODEFAULT Declination TEL TARG EQUINOX 2000 3000 2000 Equinox TEL ROT OFFANGLE 0 0 90 0 180 0 270 0 0 Rotator offset angle deg T TEL AG START TF T Acquire guide star T TEL GS1 ALPHA 0 240000 0 RA of 1 guide star T TEL GSI DELTA 900000 900000 0 DEC of 1 guide star T TEL GS1 MAG 0 25 12 Magnitude of 1 guide star T TEL GS2 ALPHA 0 240000 0 RA of 2 guide star T TEL GS2 DELTA 900000 900000 0 DEC of 2 guide star T TEL GS2 MAG 0 25 12 Magnitude of 27 guide star T TEL ADC TYPE NONE NONE ADC Setting T COORD INS FILT NAME See Table 1 NODEFAULT Filter P OCS AG START TF T Start autoguiding T OCS IA START T Start Image Analysis T OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 13 of 24 Hidden parameters Parameter Range Value Function Entry TEL TARG ADDVELALPHA 15 15 0 Additional Velocity RA arcsec s T TEL TARG ADDVELDELTA 15 15 0 Additional Velocity DEC arcsec s T TEL AO TYPE AO NOONE AO NOONE DoaONECAL correction in preset T AO ONE 32 OMEGACAM img acq movetogap Works as the normal acquisition template above except that after the preset operator intervention is requested to interactively specify a telescope offset that allows to drop one bright star into CCDs gaps Image analysis can be de activated for OBs in a concatenation
13. along the CCD mosaic Y direction when observing using the starex dither pattern see Section 4 2 Range is 0 85 arcsec Default is 8 arcsec Dither pattern name Name of the dither pattern to use see Section 4 2 One of diag starext Default is diag List of tel RA offsets List of telescope offsets in right ascension in seconds of arc on the sky to be applied when observing using the generic OMEGACAM img obs offset template Range is 9999 9999 arcsec default is 0 arcsec List of tel DEC offsets List of telescope offsets in declination in seconds of arc on the sky to be applied when observing using the generic OMEGACAM img obs offset template Range is 9999 9999 arcsec default is 0 arcsec S 4 User defined P2PP entry fields INS keywords Filter Name Name of filter to be selected from the filter pull down menu Since P2PP is an off line preparation tool it is not connected to the real database of the operational instrument so that it cannot verify whether a filter is actually installed in the instrument See Table 1 for a list of filters currently available for OmegaCAM More information on filters can be found in RD1 Default is NODEFAULT user input is expected Lamp Set Calibration lamp set to use for dome flat fields In OmegaCAM two sets of lamps are available they are simply named 1 and 2 One set is declared the default and used for routine daily calibrations meanwhile the second set spare is c
14. erence Documents The following documents are referenced in this document Reference Document Number VST SPE OCM 23100 3063 11 30 10 2001 Emegst AN Instrument Control Software Design Description 805 VST SPE OCM 23100 3064 31 10 2001 O ms2CAM Observation Software Design Description VST SPE OCM 23100 3065 11 30 10 2001 D megaCAM Guide and Image Analysis Software Design Description GE MAN ESO 17220 1332 4 19 04 2004 HOS Broker for Observation Blocks User Manual p p 30 06 2010 P2PP for Surveys User Manual 1993A1 105 1206T March 1993 exposure guide for taking twilight flatfields with large format CCDs OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 7 of 24 1 4 Abbreviations and 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 ADC Atmospheric Dispersion Corrector AG Auto Guide AO Active Optics BOB Broker for Observation Blocks CCD Charge Coupled Device CS Constraint Sets ESO European Southern Observatory GS Guide Star IA Image Analysis INS Instrumentation Software Package OB Observation Block OD Observation Description N A Not Applicable P2PP Phase 2 Proposal Preparation tool SSO Solar System Object TBD To Be Defined VLT Very Large Tel
15. escope VST VLT Survey Telescope 1 5 Glossary No special definition is introduced in this manual 1 6 Stylistic Conventions The following styles are used bold in the text for commands filenames pre suffixes as they have to be typed italic in the text for parts that have to be substituted with the real content before typing teletype for examples lt name gt in the examples for parts that have to be substituted with the real content before typing bold and italic are also used to highlight words OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 8 of 24 2 OmegaCAM Templates 2 1 Introduction Observation Blocks Templates Keywords Observation Block OB an OB consists of a list of templates which themselves consist of a list of mode and instrument specific keywords The templates and keywords are translated to commands to be sent to the telescope and instrument to setup all components for the observations Following the general P2PP architecture two types of Observation Blocks can be specified ObsBlocks night time observations science and standard star exposures CalBlocks day time calibrations bias darks Night time ObsBlocks consist of the target information a single acquisition template and the observation description OD with a small selection of science observation templates The day time CalBlocks consist of a small selection of
16. et steps are larger than in jitter template 3 1 Updated table of template parameters 3 2 Updated table of template parameters 3 5 Typo in parameters table 3 6 Typo in parameters table 3 7 Added OCS STRTG 3 8 INS FILT NAME no longer a hidden parameter 3 10 DETI WINI UITI no longer a hidden parameter Corrected typo in exposure time list 3 13 Added OCS STRTG Added reference to dither pattern description Corrected size of CCD gaps 3 14 Added OCS STRTG Added reference to jitter pattern description 3 15 Updated limits of TEL TARG OFFSETALPHA DELTA 5 3 Updated description of P2PP labels 5 4 Updated table of filters 5 5 Section added 1 4 05 09 2011 2 22 Added OFFSET to list of templates 2 2 5 Added link to OmegaCAM web pages 2 3 1 Removed preamble 2 4 1 Added comment to point 3 9 of the list 3 1 3 2 Added note about IA that can be deactivated in OBs concatenation Updated table of parameters 3 6 Updated list of exposure times 3 15 Added note about return to origin keyword Updated table of parameters 5 2 Added description of Return to Origin 5 3 Updated description of Rotator offset angle Removed description of Additional Velocity in RA DEC Updated description Start Image Analysis OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 4 of 24 TABLE OF CONTENTS 1 INTRODUCTION 1 1 Scope 1 2 Applicable Document
17. eywords Rotator offset angle Start autoguiding Start Image Analysis RA of 1 2 guide star DEC of 1 2 guide star Magnitude of 1 2 GS ADC Setting Offset step size Step size in X Step size in Y Unexposed gap size in X Angle of the telescope rotator on the sky It is measured in degrees South over East Possible values range from 270 0 to 270 0 Default is 0 0 Specify if OmegaCAM autoguide corrections have to be applied The value is T F True False Default is T Specify if OmegaCAM Image Analysis is started in the acquisition The value is T F True False Default is T The right ascension of the user selected guide star in hhmmss Equinox is J2000 Default 1s 0 00 00 00 which means that the operator will interactively pick a suitable guide star or that a guide star will be selected automatically from a catalogue The declination of the user selected guide star in tddppss Equinox is J2000 Default is 0 00 00 00 which means that the operator will interactively pick a suitable guide star or that a guide star will be selected automatically from a catalogue Magnitude of the user selected guide star Default is 12 The following options are supported for the Atmospheric Dispersion Corrector ADC COORD and NONE If NONE is specified then the ADC will not be in the path during the observation If COORD is specified then the ADC will be in the path during observation a
18. eywords already set to default values should remain at the original default value in almost all cases Hidden parameters cannot be modified and will not appear at any place in P2PP 2 2 5 Overheads Overheads associated to observations with OmegaCAM are described and quantified in the OmegaCAM User Manual RD1 and on the OmegaCAM web pages http www eso org sci facilities paranal instruments omegacam doc index html OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 9 of 24 2 5 Acquisition Templates 2 3 1 Normal Acquisition During normal acquisition the telescope is preset to the target and autoguide and image analysis are initialized following this sequence of actions 1 Preset telescope and in parallel setup instrument with user specified filter 2 Apply filter and if enabled temperature dependent focus correction 3 Initialize OmegaCAM autoguide and image analysis system Normally the auxiliary CCDs located in the focal plane of the instrument are used to do autoguiding AG and image analysis IA In this case initialization of AG includes selection of guide stars usually one per guide CCD and locking of AG loop while initialization of IA consists as a minimum in the selection of IA stars and generally may include a few measurement correction iterations For observations of Solar System Objects SSOs guiding is currently not possible but differential tracki
19. ff at the end of the template but they are automatically switched off by the instrument software at the end of the OB This allows to combine several dome flat templates in the same OB without having to wait for the lamp warm up cool down times in between templates Templates that follow this procedure and that share the underlying code implementing it are OMEGACAM img cal domeflat OMEGACAM img cal gain OMEGACAM img cal quick and OMEGACAM img cal shutter 2 5 3 Sky Flat Acquires a specified number of sky twilight flats through a given filter Exposure time is computed automatically on the basis of the requested exposure level following Tyson and Gal RD9 Exposures are jittered with the same pattern as in OMEGACAM img obs jitter but larger offsets default 30 arcsec Sky flat exposures are carried out by the observatory staff during twilight User do not have to submit OBs for these kind of calibration data 1 Setup instrument with filter and initial estimate for the exposure time 2 Loop 21 Perform an exposure measure exposure level estimate exposure time for next exposure 2 2 If next exposure time outside allowed range set exposure time to a predefined default else exit loop 2 3 Ask user whether to continue if yes go to 2 1 3 For the requested number of exposures 3 1 Start scientific exposure 3 2 Start AG and IA loop 3 3 Wait for exposure to finish and readout from scientific mosaic to start 3 4 Stop A
20. ffsets OmegaCAM Instrument Software OmegaCAM Templates Manual VST MAN OCM 23100 3111 1 4 05 09 2011 18 of 24 UU Le II T T T TITST T T TTT 5 0 5 5 8 6 10 5 0 5 Figure 1 Jitter patterns for 1 to N 20 Each dot represents a pointing center The grids shown are in units of the step size that can be specified for a jitter observation 4 2 Dither patterns The purpose of dithering is to remove the imprint of inter CCD gaps the detector mosaic Offsets are taken that are sufficiently large for these gaps to fall on different parts of the sky in each exposure Co addition of the images then gives as homogeneous an exposure as possible For N exposures it is unavoidable that some parts of the image will have been seen in at most N 2 exposures Two dither strategies are offered The first diag simply offsets the telescope by the same amount between successive exposures The size of the steps X and Y is as large as the largest gap in the mosaic about 25 arcsec in X and 85 arcsec in Y For N 5 this results in the following exposure map over the field OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 19 of 24 SKY VISIBILITY 5 STEP DITHER SKY VISIBILITY 5 STEP DITHER SKY VISIBILITY 5 STEP DITHER 8 8 We 8 R Eo Ee E gt gt gt H 2 8 1 1 g 100 50 50 100 10 1
21. itions over several nights the standard image pipeline will not combine images taken over several nights Freq is used for observations which frequently visit monitor the same field on timescales ranging from minutes to months OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 23 of 24 is used for observations that map areas of the sky larger than 1 degree The combination of various field centers into one image is not considered a standard pipeline task Standard is meant for all the rest observations that consist of a single observation block Mosaic OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 24 of 24 000
22. l or SSO tracking Parameter Range Default P2PP Label Entry DET1 WIN1 UIT1 0 43200 NODEFAULT Exposure time s T SEQ NEXPO 1 100 1 Number of exposures T INS FILT NAME See Table 1 NODEFAULT Filter P OCS STRTG NODEFAULT Observing strategy P OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 17 of 24 4 Jitter and Dither Patterns 4 1 Jitter patterns The aim of jittering is to make sure blemishes on the CCDs do not wipe out particular sources or parts of the sky Masking the blemishes i e giving them zero weight in the co addition of exposures accomplishes this Jittering also helps to average out any residual systematic errors due to for example imperfect pixel response calibration Jittering does not help to bridge the inter CCD gaps of the mosaic in the focal plane The basic tactic when Jjittering is to make sure no two exposures point at the same X or Y coordinates Thus N point jitter patterns need to fill N pointings on an N x N grid such that every row and column is used exactly once This ensures that bad rows or columns are not hit repeatedly The patterns illustrated below are all derived from the same formula which can be extended to large N The principle is to keep the pattern as compact as possible but to keep the pointings reasonably far from each other as well The algorithm assigns pointings on an N N grid as follows It fir
23. l rectangles of size DX x DY unexposed These are located near the intersection of the gaps between CCD rows and columns between rows 1 and 2 or between rows 3 and 4 Placing a bright star in the center of one of these areas will keep it off the CCDs in all N exposures OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 20 24 The starext pattern has four parameters that govern its action XGAP size of the gap in X to bridge default 25 arcsec YGAP size of the gap in Y to bridge default 85 arcsec DX X size of the area to keep unexposed in the 5 pattern default 8 arcsec DY Y size of the area to keep unexposed in 5 pattern default 8 arcsec The offsets with respect to the center of the field are then 0 0 Q3 XGAP DX 2 YGAP DY 2 XGAP DX 2 3YGAP DY 2 Normally DX lt XGAP If DX gt XGAP but lt 2 XGAP then an area of 2 XGAP DX is left unexposed similarly in Y This leads to greater overlap between the CCDs but no better field coverage If DX XGAP then three of the exposures will be taken at the same X position which can cause bad columns in the CCDs to overlap The gap between rows 2 and 3 11 arcsec is 70 arcsec narrower than the other gaps in Y so if DY is chosen between 70 and 81 arcsec then a further row of seven unexposed areas is formed along the X axis Each of these gaps has a size DX DY 70 arcsec Such a pattern produce
24. nd will be set according to the telescope coordinates Size of the telescope offset steps in seconds of arc in the sky when observing using the jitter pattern see Section 4 1 Default is 1 arcsec Size of the telescope offset steps in seconds of arc in the sky along CCD mosaic X direction when observing using the diag dither pattern see Section 4 2 Range is 0 999 arcsec Default is 25 arcsec For the camera position angles 0 and 180 degrees an offset in X implies a telescope offset towards East For the camera position angles of 90 and 180 degrees an offset in X implies a telescope offset towards North Size of the telescope offset steps in seconds of arc in the sky along CCD mosaic Y direction when observing using the diag dither pattern see Section 4 2 Range is 0 999 arcsec Default is 85 arcsec For the camera position angles 0 and 180 degrees an offset in Y implies a telescope offset towards North For the camera position angles of 90 and 180 degrees an offset in Y implies a telescope offset towards East Size in seconds of arc in the sky of the area to be left unexposed along the CCD mosaic X direction when observing using the starex dither pattern see Section 4 2 Range is 0 25 arcsec Default is 8 arcsec OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 22 of 24 Unexposed gap size in Y Size in seconds of arc in the sky of the area to be left unexposed
25. ng rates may be specified While observing SSOs image analysis and active optics corrections are not performed More details can be found in RD1 2 3 2 Move Bright Star to Gap This template is used to drop a bright star down the gaps between CCDs in the mosaic in order to reduce stray light Choice of the star is performed interactively 1 Preset telescope and in parallel setup instrument with user specified filter 2 Apply filter and if enabled temperature dependent focus correction 3 Loop 3 1 Perform one exposure with user specified exposure time and display resulting image 3 2 Prompt user to select star to be dropped down the nearest gap in the mosaic or to exit loop 3 3 User selects the star offset is computed and after user confirmation applied to the telescope 3 4 Ask user whether to continue loop if yes then go to 3 1 4 Initialize OmegaCAM autoguide and image analysis system This template cannot be used in combination with differential tracking for Solar System Objects 2 4 Science Templates The science exposure templates allow the execution of science exposures with a user specified observing strategy and filter see RD1 for more information The templates perform instrument setups telescope offsets and sequences of science exposures 2 4 1 Jitter Dither and Offset Used to observe with several pointings in the sky and performing offsets in between exposures The target must be acquired with side
26. non default Hidden parameters Parameter Range Value Function Entry DET1 WIN1 UIT1 0 43200 2 60 50 4 8 40 Exposure time s T 30 1 16 24 24 1 6 1 30 40 8 4 5 0 60 2 SEQ NEXPO 1 100 20 Number of exposures T 3 7 OMEGACAM img cal monit Same as stare with 1 and composite filter Used for photometric calibration monitoring Parameter Range Default P2PP Label Entry DETI WINI UITI 0 43200 1 Exposure time s T OCS STRTG NODEFAULT Observing strategy T Hidden parameters Parameter Range Value Function Entry SEQ NEXPO 100 1 Number of exposures T INS FILT NAME See Table 1 u gri SDSS Filter 3 8 img cal quick Same as OMEGACAM img cal domeflat with N 1 and composite filter Used for a quick health check of the instrument Parameter Range Default P2PP Label Entry DETI WINI UITI 0 43200 1 Exposure time s T INS LAMP SET Set 1 Set 2 1 Calibration lamps T default non default INS FILT NAME See Table 1 r_SDSS Filter Hidden parameters Parameter Range Value Function Entry SEQ NEXPO 1 100 1 Number of exposures T 39 OMEGACAM img cal readnoise Same as OMEGACAM img cal bias with N 2 Used to measure and monitor the CCD readout noise Hidden parameters Parameter Range Value Function Entry DET1 WIN1 UIT1 0 43200 0 Exposure time s T OmegaCAM Instrument Software S
27. odification is possible fixed in column Entry e List of values in Range column several predefined named values for the keyword are possible Selection of the actual ones for template execution is done via a pull down menu P pull down menu in column Entry e Range of values in Range column the actual value should fall within a wider range of possible values indicated by for instance 0 25 100000 0 The actual one to be used for the template execution has to be entered by typing T type in column Entry Hidden parameters several templates contain so called hidden keywords These keywords are needed for the proper execution of the templates but they are not meant to be changed by the user Therefore they are hidden from the P2PP display i e no P2PP entry field is assigned to them but they appear in the exported version of the OB The user cannot modify the values of hidden keywords 3 1 OMEGACAM img acq Preset the telescope to the coordinates of the target associated with the Observation Block After telescope has been preset and if autoguiding has been enabled GSs will be acquired Operator intervention will be requested to activate autoguiding by confirming GSs selection or overriding it 1f requested For SSO observations autoguiding is not activated Image analysis can be de activated for OBs in a concatenation Parameter Range Default P2PP Label Entry TEL TARG ALPHA 0 240000
28. or the last template the number of exposures is fixed to 1 while the user can select the exposure time and filter name 2 5 Calibration Templates Calibration templates define the procedure and the parameters for the execution of calibration exposures Almost all calibration templates are executed during daytime hence there must not be an acquisition template in the corresponding calibration OBs The only templates that do not conform to this rule are the skyflat and photometric zero point calibration templates which are executed on the sky with the acq acquisition template see Sect 2 3 1 above The following types of calibration templates exist templates taking exposures without opening the shutter bias dark readnoise templates based on dome flat field exposures dome flat gain quick shutter homogeneity the twilight flatfield template and the photometric zero point calibration template 2 5 1 Bias and Dark These templates perform exposures without opening the shutter Bias and dark exposures are carried out by the observatory staff during daytime Users do not have to submit OBs for these kinds of calibration data 1 Setup CCD with user specified exposure time fixed to zero for biases 2 For the requested number of exposures 2 1 Start exposure without opening the shutter 2 2 Wait for exposure to finish shutter is closed and readout from scientific mosaic to start 2 3 Setup exposure time for next ex
29. posure 2 4 Wait until readout has finished and data from the FIERAs has been written to disk 2 5 Start asynchronous i e parallel merging of data products in final FITS file to be archived 2 6 Go to 2 1 3 Wait for all acquired data to be merged in final files and archived Templates that follow this procedure and that share the underlying code implementing it are OMEGACAM img cal bias OMEGACAM img cal dark and OMEGACAM img cal readnoise 2 5 2 Dome Flat Performs exposures with the CCD illuminated by the light coming from the calibration lamps set Note that in OmegaCAM two such sets exist see Sect 5 4 for more details Dome flat exposures are carried out by the observatory staff during daytime User do not have to submit OBs for these kind of calibration data 1 Ifnotalready on then switch lamps on setup CCD with user specified exposure time insert requested filter 2 Wait for lamps warm up if not already warm 3 For the requested number of exposures 3 1 Start exposure 3 2 Wait until readout has finished and data from the FIERAs has been written to disk 3 3 Start asynchronous i e parallel merging of data products in final FITS file to be archived 3 4 Go to 3 1 4 Wait for all acquired data to be merged in final files and archived OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 11 of 24 Note that calibration lamps are not switched o
30. real tracking only i e jitter and dither is not provided for observations of Solar System Objects This check will be performed by the P2PP verification software 1 Offset telescope and in parallel setup first exposure exposure time and filter name 2 Apply filter and if enabled temperature dependent focus correction 3 Forthe requested number of exposures 3 1 Check that if enabled AG and IA are setup correctly 3 2 Start scientific exposure 3 3 Start AG and IA loop 3 4 A few seconds before the end of the exposure stop AG and IA loop 3 5 Wait for exposure to finish shutter is closed and readout from scientific mosaic to start 3 6 Offset telescope and in parallel setup next exposure exposure time and filter name 3 7 Apply filter and 1f enabled temperature dependent focus correction 3 8 Wait until readout has finished and data from the FIERAs has been written to disk 3 9 Go to point 3 1 it is possible to disable this for the Offset template in P2PP 4 Offset telescope back to preset position 5 Wait for all acquired data to be merged in final files and archived 2 4 2 Stare Used to observe with one fixed pointing position Target can be acquired with either sidereal or non sidereal tracking 1 Setup first exposure exposure time and filter name OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 10 of 24 2 Apply filter and if enabled
31. ross calibrated against the first Once the lifetime of the default set of lamps has expired its role is taken over by the other set which then becomes the default and the former set is replaced with new lamps For further information see RD2 The user has the option to select the default set the non default one or explicitly set 1 or 2 Not surprisingly the default is to use the default lamp set Table 1 OmegaCAM filters in P2PP Filter Namein P2PP Filter Type u SDSS SDSS v g SDSS SDSS g r SDSS SDSS i SDSS SDSS 1 z SDSS SDSS z B_JOHN Johnson B V_JOHN Johnson V v_STRM Str mgren v H ALPHA Ha 4 quadrants redshifts 0 0 01 0 02 0 03 NB 659 Ha redshift 0 private filter VPHAS u_g ri SDSS SDSS il NB 454 494 533 575 Mosaic of four blue narrow band filters private NB 617 710 755 817 Mosaic of four red narrow band filters private NB 852 861 869 878 Night sky leak filter private filter Munich Obs opaque Opaque aluminium filter for protection 5 5 User defined P2PP entry fields OCS keywords Strategy Observing strategy This keyword is not used by the ESO data reduction pipeline but may be used to specify observations taken with a particular purpose This information is taken into account in some of the OmegaCAM consortium s data processing Possible values are Deep Freq Mosaic and Standard Deep is for deep integrations possibly taken at selected atmospheric cond
32. s 1 3 Reference Documents 1 4 Abbreviations and Acronyms 1 5 Glossary 1 6 Stylistic Conventions 2 OMEGACAM TEMPLATES 2 1 Introduction Observation Blocks Templates Keywords 2 2 OmegaCAM Templates Acquisition Science and Calibration 2 2 1 OmegaCAM Observing Modes 2 2 2 Offsetting Modes and Observing Strategies 2 2 3 Template Types 2 2 4 Template Keywords 2 2 5 Overheads 2 3 Acquisition Templates 2 3 Normal Acquisition 2 3 2 Move Bright Star to Gap 2 4 Science Templates 2 4 1 Jitter Dither and Offset NO NONO WD MM GGG Go Go oo GD JJ OO CO Ch 2 24 2 Stare 2 5 Calibration Templates 10 2 5 1 Bias and Dark 10 2 5 2 Dome Flat 10 2 5 3 Sky Flat 11 2 5 4 Photometric Zero Point Calibration 11 3 TEMPLATES DESCRIPTION 12 3 1 OMEGACAM img acq 12 32 OMEGACAM img acq movetogap 13 3 3 OMEGACAM img cal bias 13 34 OMEGACAM img cal dark 13 3 5 OMEGACAM img cal domeflat 13 3 6 OMEGACAM img cal gain 14 3 7 OMEGACAM img cal monit 14 3 8 OMEGACAM img cal quick 14 3 9 img cal readnoise 14 3 10 OMEGACAM img cal shutter 15 3 11 OMEGACAM img cal skyflat 15 3 12 OMEGACAM img cal zp 15 3 13 OMEGACAM img obs dither 15 3 14 OMEGACAM img obs jitter 16 OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 5 of 24 3 15 OMEGACAM img obs offset 16 3 16 OMEGACAM img obs stare 16 4 JITTER AND DITHER PATTERNS 17 4 1 Jitter patterns 17 4 2 Dither patterns 18
33. s rather large unexposed areas along the wider dead rows though SKY VISIBILITY 5 STEP DITHER SKY VISIBILITY 5 STEP DITHER SKY VISIBILITY 5 STEP DITHER g gt x nN 2 10 o 10 8 10 0 10 SES X mm X mm X mm Figure 4 Relative exposure level over the field in a 5 point starext dither pattern The central square in the right hand panel is left unexposed OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 21 of 24 5 Explanations of the P2PP Entry Fields 5 1 User defined 2 entry fields DET keywords Exposure Time Exposure Level Exposure time of an individual exposure in seconds Default is NODEFAULT user input is expected The shortest exposure time for OmegaCAM shutter is 1ms see RD1 for more details Requested intensity level in ADUs This parameter is used by OMEGACAM img cal skyflat template to compute the exposure time for sky flats Default is 20000 ADU 5 2 User defined P2PP entry fields SEQ keywords Number of Exposures Return to Origin The number of exposures to be taken for a given instrument setup This is the total number of exposures that will be taken by the respective template Default is 1 Specify 1f at the end of an offset sequence the telescope returns to the start of the sequence The value is T F True False Default is T 5 3 User defined P2PP entry fields TEL k
34. st fills in the central 0 1 2 or 3 pointings leaving a multiple of 4 Those pointings are then arranged as a set of nested rotated squares new ones being added alternately on the outside and on the inside of the grid In detail the algorithm for an N point jitter is N4 int N 4 number of outer squares to make L N 2 0 5 grid points are L 1 1 1 1 L in X and Y Assign central 0 1 2 or 3 points if N 4 20 X Y if 4 1 X 0 Y 0 if N 4 2 X 0 5 0 5 Y 0 5 0 5 if N 4 X 1 0 1 Y 1 1 0 D 0 5 1 N 4 first positive X or Y position still empty for i 0 to N4 1 construct N4 squares a b is the corner if 1 2 0 make corner with X as large Y as small as possible a L 0 5 i b D 1 5 i else make corner with X and Y as small as possible 0 5 1 5 1 b a 1 if int a 2 0 flip every second square a a X X concat a b a b Y Y concat b a b a On output X and Y are the X and Y offsets with respect to the center in units of a step size The step size is be chosen by the user and should be of the order of an arcsecond The patters for N 1 to 20 are shown in Figure 1 below For very large N this pattern is no longer optimal it tends to populate the diagonals of the grid More evenly spread solutions exist Note that OmegaCAM offset patterns need to be specified as relative offsets with respect to the previous position the jitter template converts the absolute X and Y from the above recipe to relative o
35. tion Entry DET1 WIN1 UIT1 0 43200 0 Exposure time s T 34 img cal dark Acquire N dark exposures with opaque filter in optical path and shutter closed The user specifies integration time Parameter Range Default P2PP Label Entry DET1 WIN1 UIT1 0 43200 NODEFAULT Exposure time s T SEQ NEXPO 1 100 1 Number of exposures T 35 img cal domeflat Acquire N dome flats Telescope is preset to point towards the flat field screen without tracking calibration lamps are switched ON automatically The user specifies exposure time OmegaCAM Instrument Software VST MAN OCM 23100 3111 S OmegaCAM Templates Manual 14 05 09 2011 14 of 24 Parameter Range Default P2PP Label Entry DET1 WIN1 UIT1 0 43200 NODEFAULT Exposure time s T SEQ NEXPO 1 100 1 Number of exposures T INS FILT NAME See Table 1 NODEFAULT Filter P INS LAMP SET Set 1 Set 2 1 Calibration lamps P default non default 3 6 img cal gain Same as OMEGACAM img cal domeflat with N 20 and exposure time 0 2 4 3 4 0 0 3 0 7 3 5 2 7 0 1 1 4 2 1 2 1 1 4 0 1 2 7 3 5 0 7 0 3 4 0 4 3 0 2 s Used to determine and monitor CCD gain Parameter Range Default P2PP Label Entry INS FILT NAME See Table 1 NODEFAULT Filter INS LAMP SET Set 1 Set 2 1 Calibration lamps P default
36. uctions about scheduling of observations and reduction of data products The Observation Strategies currently defined for OmegaCAM are STANDARD FREQ DEEP and MOSAIC They can be specified by the user using P2PP during the preparation of the scientific OBs Offsetting Modes and Observing Strategies are described in detail in the OmegaCAM User Manual RD1 2 2 3 Template Types Three template types are used with OmegaCAM target acquisition templates science observation templates and mostly day time calibration templates The following naming convention see AD3 is used Acquisition templates OMEGACAM img acq xxx Calibration templates OMEGACAM img cal xxx Observation templates OMEGACAM img obs xxx 2 2 4 Template Keywords The parameters of the templates and the respective observations are to be specified in the template specific list of keywords The keywords correspond to functionalities for instance setups of the instrument telescope preset supported by the templates Within P2PP the keywords are designated by the names of P2PP entry fields For any keyword an allowed range and a default value is defined The keywords themselves are not visible from P2PP The tables in section 3 list separately for each template the keywords names their value range and defaults together with the P2PP name as shown in the view panel of P2PP In general only the keywords which will be in status NODEFAULT have to be set by the users while the k
37. ult P2PP Label Entry DET1 WIN1 UIT1 0 43200 NODEFAULT Exposure time s T SEQ NEXPO 1 100 1 Number of exposures T TEL TARG OFFSETSIZE 0 5 10 1 Offset step size arcsecs T INS FILT NAME See Table 1 NODEFAULT Filter P OCS STRTG NODEFAULT Observing strategy P 3 15 img obs offset Observe with N pointings in the sky with user defined offsets in between exposures Offsets are relative to the respective previous position in the sequence If fewer offset are defined than the number of exposures requested the list of offsets is cycled through Target acquired with sidereal tracking only By default the telescope is moved back to the origin at the end of the offset sequence This option can be disabled by setting the Return to Origin keyword to False F in P2PP Parameter Range Default P2PP Label Entry DET1 WIN1 UIT1 0 43200 NODEFAULT Exposure time s SEQ NEXPO 1 100 1 Number of exposures T SEQ RET2ORIGIN T Return to origin T TEL TARG OFFSETALPHA 9999 9999 0 0 List of tel RA offsets arcsec T TEL TARG OFFSETDELTA 9999 9999 0 0 List of tel DEC offsets arcsec T INS FILT NAME See Table 1 NODEFAULT Filter P OCS STRTG NODEFAULT Observing strategy Hidden parameters Parameter Range Value Function Entry SEQ NTOSKIP 0 99 0 Number of exposures to skip T 3 16 OMEGACAM img obs stare Observe with one fixed pointing position Target acquired with either siderea
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