1.1-D-035-G WFCAM Functional and Performance Requirements v2
Contents
1. WFCAM ee UKIRT WE Document Title WFCAM Functional and Performance Requirements Document Number 1 1 d035 G Issue 2 2 Date 9 02 04 Document Mark Casali Signature and Date Prepared By Document Signature and Date Approved By Document Signature and Date Released By UK Astronomy Technology Centre H ukirt WFCAM Documents Active 1 1 D 035 G Function and Performance Requirments v2 2 doc WFCAM RER UKIRT IN CHANGE RECORD Document Number 1 1 d 035 G Issue 2 2 Category Systems Staus Issued Author M Casali Date 9 2 04 Issue Date Section affected Change Description 1 0 10 1 01 First draft MMC 1 1 29 01 01 Alterations following talk with Steve Warren MMC 1 2 15 02 01 Revised FPRD following requirements review MMC 1 3 25 04 01 Inserted WCS astrometry and MEF format requirements after S W meeting with CASU WFAU 1 4 13 09 01 All Reformed document VR 4 5 26 09 01 1 3 1 6 1 12 1 15 Inserted bright magnitude limits in 1 3 Revised tip tilt 1 17 spec in 1 6 Revised filter definitions 1 12 Rewording of system efficiency 1 15 Added autoguider focal plane flexure requirement in 1 17 Throughput requirement set equal to UFTI MMC 1 6 22 10 01 All Revised following discussion with WFCAM team 1 7 15 4 02 1 9 1 18 Revised section 1 9 Modified mass limits in 1 18 1 8 2 102. no microstepping 2x2 and 3x3 patterns TIP TILT SECONDARY MIRROR WFCAM shall have a tip tilt secondary mirror amp hexapod The M2 loop control shall be capable of operating at faster than 85 Hz The full system latency measured from the centre of the CCD integration shall be less than 25 ms H ukirt WFCAM DOCUMENTS Active 1 1 D 035 G WFCAM Functional and Performance Requirements v2 2 doc Document Number 1 1 d 035 G Issue 2 2 WFCAM E Se UKIRT WR Staus Issued 1 7 1 8 1 9 8 of 13 Author M Casali Date 9 2 04 OPTICAL IMAGE QUALITY a Optics Encircled Energy requirement 80 EE within 2 sec z diameter goal 80 EE within 1 2 sec z gt b Optics MTF requirement gt 0 5 sec z at 1 2 cycles per arcsecond following refocusing and hexapod secondary mirror adjustment from a look up table z is the Zenith angle of the observations These requirements apply over the whole science field c The project shall supply a table or formula for the calculation of M2 position vectors as a function of telescope attitude 3 5 GHOSTING AND STRAYLIGHT a Ghosts and stray light arising from a point source in the field should have a peak intensity lt 0 1 of the point source peak itself b Total diffuse stray light from a uniform background sky should not add more than 5 to the background and should not vary by more than 10 on scales below 14 ar
3. 02 2 4d Removed 48 hour cool down requirement 1 18d Lifting mass limit unchanged at 1250 kg 1 18e Included CoG specification 2 4f Removed requirement on ability to pre cool while on telescope IER Added full frame AG CCD readout capability 117d Guide star mag limit no longer relevant performance now required within observing efficiency budget 2 0 27 1 03 21 Revised deliverable documents 2 1 23 7 03 1 16d 1 16f 1 16i These sections removed following transfer of 1 17f 2 9a responsibilities to JAC and CASU 1 16d Inserted requirement for engineering pipeline q 8 8 PIP 2 2c Added note on list of spare parts 1 17g Removed requirement for change to UKIRT pointing model Will use current model as agreed with JAC ER Added requirement to provide M2 vector description as a function of telescope attitude Added details of auxiliary handling equipment 1 11 D Refererence to ukirt pointing model included 2 2 9 02 04 1 9a modifed to 94 spacing 2 of 13 H ukirt WFCAM DOCUMENTS Active 1 1 D 035 G WFCAM Functional and Performance Requirements v2 2 doc WFCAM RER UKIRT IN APPLICABLE DOCUMENTS Document Number 1 1 d 035 G Issue 2 2 Category Systems Staus Issued Author M Casali Date 9 2 04 Reference Document Title Document Number Issue amp Date AD1 Operational Concepts Definition Document 1 1 d 040 G V1 2 1 11 01 3 of 13 H ukirt WF
4. and pumping lines Requirement removed e Conductive and radiative links should be such that the detector focal plane should not be able to cool down or warm up at faster than 0 5 degrees per minutes f It shall be possible to pump WFCAM while it is on the telescope WFCAM must be able to remain cold and operational for at least 4 months POWER LOSS BAD WEATHER The detectors and all mechanisms must be secure against damage when power returns WINDOW CONDENSATION Cryostat optics especially the window shall not be subject to condensation during normal operating conditions INSTALLATION AND HANDLING RIGS The following auxiliary equipment will be delivered with wfcam 1 Michelle rig mounting bracket guide cone I beams castors 2 Service stand slotted guide cone 3 Field lens tower mount I beams 4 Lifting attachments for the top ring assembly 5 Spreader bar for assembling top ring and cryostat components 6 Expanding mandrel for assembly of tertiary mirror bezel x 2 7 Lifting plug for tertiary mirror 8 M8 swivel lifting rings x 3 used on optics bezels MONITORING WFCAM STATUS a The operator must be able to confirm vacuum and temperature status from the control room without requiring the pipeline to generate quality control information b It will be possible to confirm WFCAM status from Hilo MONITORING DATA QUALITY a Removed b Since the camera will be expected to operate for long periods without
5. operator intervention audible and visually obvious warnings should be issued when any key parameters are outside operational limits H ukirt WFCAM DOCUMENTS Active 1 1 D 035 G WFCAM Functional and Performance Requirements v2 2 doc Document Number 1 1 d 035 G Issue 2 2 WFCAM Se Se UKIRT WR Staus Issued Author M Casali Date 9 2 04 2 10 SAFETY WFCAM shall be compliant with both UKATC Health and Safety regulations http intra roe ac uk atc admin health _safety manual index html and JAC Health and Safety Regulations http www jach hawaii edu JACpublic JAC docs safeman 13 of 13 H ukirt WFCAM DOCUMENTS Active 1 1 D 035 G WFCAM Functional and Performance Requirements v2 2 doc
6. 8 1 17 1 33 gt 90 0 1 H98 1 49 1 78 gt 90 0 1 K98 2 03 2 37 gt 95 0 1 H2 1 0 S1 2 111 2 132 gt 75 0 1 For an incident angle of 10 degrees at operating temperature COLD STOP WFCAM shall have a cold stop at a re imaged pupil FOCUSSING The camera must be delivered with warm and cryogenic focussing procedures and mechanisms sufficient to allow the optical quality requirements to be achieved and maintained SYSTEM SURVEY EFFICIENCY For a survey which uses a 2x2 microstep and 10 seconds integration at each microstep point the system efficiency defined as photon integration time elapsed time averaged over a night shall be greater than 65 OPERATING MODES AND DATA HANDLING a The telescope and camera combination should function semi automatically mapping large areas of sky with operator intervention required only to start a new survey or to attend to acquisition or observing failures b It will be the WFCAM Project s task to define interfaces with the Wide Field Astronomy groups and to follow and help co ordinate the progress towards a streamlined pipeline from the summit to the end user in the UK until completion of WFCAM summit commissioning c WEFCAM must present a user friendly interface in the manner of other common user instruments for visiting astronomers d An engineering pipeline running under ORACDR will be delivered to enable instrument performance to be checked during
7. CAM DOCUMENTS Active 1 1 D 035 G WFCAM Functional and Performance Requirements v2 2 doc Document Number 1 1 d 035 G Issue 2 2 WFCAM EE Se UKIRT WR Staus Issued Author M Casali Date 9 2 04 TABLE OF CONTENTS DOCUMENT FLOW gees e eege ege deeg ENEE EES EEN Eer 5 INTRODUCTION svssscicessescedevsevssscssccadccsveessevsascescessscsseccessvces veseseus csaseucouvesvesnesocsdecsssseesouseseuscsnsvesvosveoesseensovevedseuses 6 Tee INSTRUMENT WE 7 1 1 D ELE TEE H 1 2 NUMBER AND TYPE OF DETECTORS merroricsee dari eieeto Tie rnE ne Inian AREE OK EENE CaN EENEN EEEo T EEEIEE T EE a EEEa 7 1 3 CHARACTERISTICS OF DETECTOR CONTROLLER OPERATION 7 1 4 BACKROUND AND THROUGHPUT ies esoe EE EENS ER AEN Ee 7 1 5 PIXEL SIZE AND MICROSTEPPING sscccccscacsecsccaccecsstacsssescaveeccscacaedectneveceetncnesesvasvectecadnecestnetecestacnesssenevecens 7 1 6 TIP TILT SECONDARY MIRROR ereenn enen cos ee EEN AEN Ee 7 1 7 OPTICAL IMAGE QUALITY EE 8 1 8 GHOSTING AND STRAY LIGH T orrec enere NEEE DEENS AE 8 1 9 FOCAL PLANE LAYOUT osgcsisicsoiisootedengsisiassede aa saian asaras oS Eo a ar aa asa EEs ieai ine eiei 8 1 10 PHOTOMETRIC ACCURACY occcccccccccccsssssssecececsesssaeceeececseseseceeeeccsensssaeeeeeceesessaeeeccceeseaueseeececsensaaseeeeeeees 8 ILII ERC ER EE 8 TED E n H 9 LIS COLD STOR oneone nas aaen ea ose decevonsbungncesbeanvanadanss ocemesdveastensesseganss cuaneagverseaecdeaeesewwoss 9 LIA FOCUS
8. DETECTOR CONTROLLER OPERATION The detector controller combination shall be such that in operation under highest background conditions the system will not saturate on stars as bright as J 15 H 14 K 13 5 The electrical crosstalk rejection in the controllers shall be more than 94 db The system noise in a single Correlated Double Sample will be less than 36 electrons The controller will allow the following read schemes 1 correlated double sampling it multiple up to 100 non destructive reads iii row by row read reset read tv sub array readout allowing exposures shorter than 0 2 seconds Individual detector assemblies and the entire focal plane itself must be safe against electrostatic damage with normal operational handling BACKROUND AND THROUGHPUT Removed Identical to 1 3a The internal cryostat thermal background must not add more than 5 to the total background including sky emission in any filter The Telescope WFCAM throughput excluding filter and detector should be greater than 60 in all bands and over the entire science field H PIXEL SIZE AND MICROSTEPPING The pixel size will be 0 40 0 004 1 arcsecond pixel at 2 2 microns over the whole field WFCAM UKIRT shall be capable of accurate microstepping to 0 033 arcseconds 1 12 of an IR pixel over a region of 8 arcseconds 20 IR pixels The definition of the number of microsteps and their precise offsets should be definable in software for 1
9. SING E 9 1 15 SYSTEM SURVEY EPPICIENCN 9 1 16 OPERATING MODES AND DATA HANDLINO 9 LI AUTOGUMER Sei ssssssgedecesteiss3 sdacceadensaanesseeds cae onanabaccgnyassvendtarseceeusdavanateans a NEE EES ER aR ENTEND a STEET EERENS 10 1 18 MECHANICAL STIFFNESS STABILITY AND MASS 10 2 OPERATIONAL REQUIREMENTS 2 ssccssscssssscssscesssscssscsssessssccsssessssscsssessssscsssassssssssassssssssassssseess 11 2 1 IR eieien Ein NR E 11 2 2 BEREEDEN es Ss eS 11 2 3 WECAM PRE INSTALLATION sis ege ee 11 2 4 WFCAM CRYOGENICS AND COOL DOWN TIMES 12 2 5 POWER a EEN EE 12 2 6 WINDOW CONDENSA TION EE 12 2 7 INSTALLATION AND HANDLING RIGS ccccccsssssssssscssscscecseeeeessesesueesuseeusesusesusususesuseeusesuansuaeeuaneuanauaneuees 12 2 8 MONITORING WFCAM STATUS ege eege Ee denen 12 2 9 MONITORING DATA QUALITY EE 12 2 10 SAFETY EE 13 4 of 13 H ukirt WFCAM DOCUMENTS Active 1 1 D 035 G WFCAM Functional and Performance Requirements v2 2 doc Document Number 1 1 d 035 G Issue 2 2 WFCAM Ger Ser Se UKIRT WR Staus Issued Author M Casali Date 9 2 04 DOCUMENT FLOW WFCAM Requirements Documents Sunday October 21 2001 Science Programme Functional and Performance Requirements Costs amp schedule Operational Concepts Definition constraints System Budgets Sub syste
10. c minutes FOCAL PLANE LAYOUT a The focal plane configuration shall have 4 detectors spaced by 94 1 of their active area on a NSEW grid b The row and column directions of the detectors shall be co aligned to within 0 5 degtees c The 4 detectors shall be sufficiently co planar to achieve the required image quality PHOTOMETRIC ACCURACY WFCAM instrumental characteristics should not stop the achievement of relative photometric accuracy between point sources in a single IR science field at a level of 1 after routine calibration ASTROMETRY a WFCAM instrumental characteristics should not stop the achievement of relative astrometric accuracy between point sources in a single IR science field of 0 1 with a goal of reaching 0 05 b WFCAM shall use the UKIRT pointing model H ukirt WFCAM DOCUMENTS Active 1 1 D 035 G WFCAM Functional and Performance Requirements v2 2 doc WFCAM RER UKIRT IN 1 12 9 of 13 Document Number 1 1 d 035 G Issue 2 2 Category Systems Staus Issued Author M Casali Date 9 2 04 FILTERS WFCAM shall have a minimum of 6 filter mechanisms goal of 8 with the following filters Wavelengths are for normal incidence except where otherwise stated filter 50 point 50 point peak Out of band short A um long A um transmission transmission specification blank Y 0 97 1 07 gt 80 0 1 J9
11. integration and test and commissioning Major instrumental characteristics will be removed and object extraction done H ukirt WFCAM DOCUMENTS Active 1 1 D 035 G WFCAM Functional and Performance Requirements v2 2 doc Document Number 1 1 d 035 G Issue 2 2 WFCAM saa Sa WR UKIRT WR Staus Issued Author M Casali Date 9 2 04 Raw data for distribution to the Wide Field Astronomy Units will be in a mutually agreed format Removed It must be possible to carry out calibration observations required at appropriate points in the night The WFCAM project will deliver hardware for the summit pipeline which measures data quality and warns of problems Removed WFCAM must have an engineering mode in which sub systems can be controlled and exposures taken without requiring a full survey definition to be entered WFCAM shall have simple start up and shut down procedures 1 17 AUTOGUIDER a b Gm mo Er The autoguider must be able to automatically acquire a guide star within a box of up to 8 arcsec on a side centred on the guide star catalogue position Any flexure between autoguider and science focal plane must be less than 1 5 microns 0 033 arcsec over 10 minutes of observing at zenith Observing preparation tools must assign guide stars for each pointing off line from catalogues Removed Replaced by autoguider observing efficiency budget The autoguider must satisfy the mic
12. m specifications Sub System Design 5 of 13 H ukirt WFCAM DOCUMENTS Active 1 1 D 035 G WFCAM Functional and Performance Requirements v2 2 doc Document Number 1 1 d 035 G Issue 2 2 WFCAM n E UKIRT WR Staus Issued Author M Casali Date 9 2 04 INTRODUCTION The top level requirements and specifications for WFCAM which emerge from consideration of the science goals and modes of operation are set out below Broadly these requirements attempt to ensure that the end product of WFCAM observations is the desired science They are the result of ongoing revisions of the FPRD first presented at the WFCAM Conceptual Design Review in 1999 Requirements deriving directly from instrument functionality and performance are presented in section 1 Those deriving from operational and instrument support considerations are in section 2 Background information to the requirements is presented in the Appendix 6 of 13 H ukirt WFCAM DOCUMENTS Active 1 1 D 035 G WFCAM Functional and Performance Requirements v2 2 doc Document Number 1 1 d 035 G Issue 2 2 WFCAM S a Se UKIRT WR Staus Issued 1 1 1 2 1 3 1 4 gt 1 5 1 6 o 7 of 13 Author M Casali Date 9 2 04 INSTRUMENT FUNCTIONS WFCAM will be an imager only NUMBER AND TYPE OF DETECTORS WFCAM will use 4 Hawati 2 PACE HgCdTe detectors CHARACTERISTICS OF
13. rostepping requirements Removed Removed It must be possible to read out the CCD full frame though not at 40Hz 1 18 MECHANICAL STIFFNESS STABILITY AND MASS a 10 of 13 The mechanical alignment stability must be such that optical quality after re focussing and secondary mirror re centreing does not degrade outside specifications as the telescope moves between zenith and 2 air masses 60 zenith angle or with temperature variations of 5 to 5 C within the UKIRT dome WFCAM should remain in focus ie optical quality remains within spec in all normal environmental conditions with no more than one instrument internal refocus per hour It will be possible to make temperature and attitude dependent adjustments of the secondary mirror and internal focus via a look up table or mathematical model to remove predictable focus drifts Total instrument mass to be lifted on to the telescope as a single unit shall not exceed 1250 ke The instrument centre of gravity shall be 1 540 2m above the M1 plug interface H ukirt WFCAM DOCUMENTS Active 1 1 D 035 G WFCAM Functional and Performance Requirements v2 2 doc Document Number 1 1 d 035 G Issue 2 2 WFCAM saa Sa Se UKIRT WR Staus Issued 2 1 2 2 2 3 11 of 13 Author M Casali Date 9 2 04 OPERATIONAL REQUIREMENTS These requirements have to do with operational support of WFCAM at the telescope and ensuring that all necessa
14. ry hardware and software are in place at commissioning DOCUMENTATION The following shall be provided in electronic and paper form with delivery of the instrument 1 Operation and Maintenance Manual includes recommended spares list 2 Instrument User Manual 3 Drawing set Mechanical amp Electrical SPARE PARTS a Spare parts should be provided for components liable to failure which have long lead times to delivery b Spare parts necessary for fault diagnosis should be provided c The precise list of spare parts shall be agreed in a separate document WFCAM PRE INSTALLATION While WFCAM is still in its servicing cart before installation on the telescope it will need to be possible to measure internal vacuum and temperature values determine satisfactory electronics and detector operation Autoguider operation H ukirt WFCAM DOCUMENTS Active 1 1 D 035 G WFCAM Functional and Performance Requirements v2 2 doc Document Number 1 1 d 035 G Issue 2 2 WFCAM E Se UKIRT WR Staus Issued 2 4 2 5 2 6 2 7 2 8 2 9 12 of 13 Author M Casali Date 9 2 04 WFCAM CRYOGENICS AND COOL DOWN TIMES a WECAM will be mounted above the primary mirror and any coolant or cryogenic spillage must be prevented b Regular cryogenic operation should be achieved with a closed cycle helium refrigerator c The fridge should be compatible with existing UKIRT compressors
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