Telescope and Instrument Performance Summary (TIPS)

Transcription

1 Telescope and Instrument Performance Summary (TIPS) 2 May 2002 AGENDA 1. SISD Perspective Harry Ferguson 2. SMOV3B Update Carl Biagetti 3. ACS Update Adam Riess 4. NICMOS Update Torsten Boeker 5. WFPC2 Update Anton Koekemoer Next TIPS Meeting: 16 May 2002

2 SISD Perspective The instruments are working great! ACS sensitivity better than advertised in the prime bands. NICMOS sensitivity is likely to be better than advertised. FGS stability better than before WFPC2 & STIS back in business ACS/SBC last remaining detector to comission Calibration Plans for cycle-11 Director s office reviews: this afternoon for WFPC2, STIS, FGS Week of May 20 for ACS & NICMOS Phase 2 submissions: May 15 WFPC2, STIS, FGS: special commanding or early execution June 7 ACS, NICMOS: special commanding or early execution June 21: The rest 2 May 2002 H. Ferguson TIPS 1

3 Calibration workshop Cross-instrument activities October 17-18, 2002 immediately after ADASS Brad Whitmore and Santiago Arribas chair the LOC SHARE/FASST Blades committee Heritage instrument archives: ST-ECF will reprocess and deliver FOS data CADC will reprocess and deliver GHRS data WFPC2 next in line Registration, CR-rejection, & astrometry improvements Dither working group Strawman algorithms being drawn up by subgroups: Dither now metadrizzle in python Registration how to register various types of images 2 May 2002 H. Ferguson TIPS 2

4 May all your anomalies be minor 2 May 2002 H. Ferguson TIPS 3

5 TIPS 02May02 Carl Biagetti/NISD SMOV3B SMOV3B PROGRESS

6 SMOV3B TIPS 02May02 Carl Biagetti SMOV3b PLAN MEASURE/MONITOR NEW SPACECRAFT BEHAVIOR POINTING, THERMAL, POWER RECOMMISSION EXISTING SIs STIS, WFPC2 COMMISSION NEW SIs ACS Science/EROs in early April ACS SMOV complete in early June REVIVE AND RECOMMISSION NICMOS VIA NCS COOLDOWN Science/EROs in early May NICMOS SMOV complete in early August Page 2

7 SMOV3B TIPS 02May02 Carl Biagetti ---SPACECRAFT & EXISTING INSTRUMENTS --- Progress since 4 April TIPS PCS - Vehicle Disturbance Test (VDT) analysis uncovers PCS control-law bug that was causing anomalous jitter Jitter was also seen in FGS data Corrected last week STIS - Recommissioned MAMA & CCD science has been re-enabled and has resumed STIS SMOV complete WFPC2 - Recommissioned UV Monitoring complete GO science enabled and has resumed WFPC2 SMOV complete FGS - Recommissioned Guiding and astrometry Jitter test to be repeated after PCS control law update Page 3

8 SMOV3B TIPS 02May02 Carl Biagetti --- NEW INSTRUMENTS --- Progress since 4 April TIPS ACS Coarse/fine alignment completed 2 April ERO observations performed 1 9 April Media release 30 April SBC activation delayed to early May NICMOS Cooled to target temperature (~ 75 degk) NICMOS re-enabled 19 April intentionally safed on 28 March to facilitate cooldown Filter Wheel test completes today Page 4

9 SMOV3B TIPS 02May02 Carl Biagetti SMOV PROGRESS AS OF 01 MAY PLANNED ACTIVITIES COMPLETED ACTIVITIES PERCENT COMPLETE SPACECRAFT ACS ERO NCS NICMOS STIS WFPC ======= ======= ======= ======= ======= TOTAL Page 5

10 Release SMOV3B MAJOR SMOV MILESTONES UPDATED AS OF 01 May 09 March NICMOS Cooldown 18 Mar 12 Apr (17 day delay) STIS Basic CCD GO Science WFPC2 Cooldown WFPC2 GO Science 22 March 22 March 26 March TIPS 02May02 Carl Biagetti ACS ALIGN 22 March 2 April 5 days ahead of plan ACS CCD EROs April ~ 1 week ahead of plan ACS Basic GO/GTO Science (CCD) 11 April on schedule STIS MAMA GO Science 15 April delayed ~ 2weeks for long NICMOS cooldown NICMOS Filter Wheel Test 23 April 02 May ~ 4 week delay NICMOS Alignment (PAM focus) May ~ 4 week delay NICMOS EROs May ~ 2 week delay NICMOS Basic GO Science Enable 10 May (approx.) ~ 2 week delay (without fine aperture locations) ACS Coronography Enabled (incl. EROs) 09 June ~ 3 weeks ahead of plan NICMOS Coronography Enabled 12 August SMOV Complete Page 6

11 SMOV3B TIPS 02May02 Carl Biagetti ACS SMOV SCHEDULE ID Task Name 38 HST RELEASE ACS02 - ACS LOAD & DUMP ON-BOARD MEM ACS03 - ACS SCIENCE DATA BUFFER CHEC ACS06 - ACS CCD TEMP SET POINT DETER ACS05 - ACS CCD FUNCTIONAL ACS05 ACS DAILY TEST ACS13 - ACS COARSE ALIGNMENT ACS31 - ACS CCD HOT PIXEL ANNEALING ACS14 - ACS FINE ALIGNMENT HST FOCUS MON (WFPC2/ACS/STIS) ACS EROs Mar 10, '02 Mar 17, '02 Mar 24, '02 Mar 31, '02 Apr 7, '02 Apr 14, '02 Apr 21, '02 Apr 28, '02 May 5, '02 May 12, '02 May 19, '02 May 26, '02 Jun 2, '02 Jun 9, '02 Jun 16, '02 Jun 23, '02 Jun 30, '02 F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T 3/9 28 ACS BASIC CCD SCIENCE ENABLE ACS11 - ACS/FGS ALIGNMENT ACS15 - ACS IMAGE QUAL & PSF MEAS ACS28 - ACS CCD GEOMETRIC DISTORTIO ACS05 ACS CTE TEST ACS32 - ACS CCD PRE-FLASH TEST ACS10 - HRC CONTAM MONITOR ACS16 - HRC COR'GR'IC REPEATABILITY 4/ ACS20 - ACS SENSITIVITY ACS18/19 - HRC FF STABILITY ACS08 - SBC ACTIVATION 9 PRD SIAF UPDATE ACS09 - SBC FOLD ANALYSIS FOR ANOM R ACS29 - ACS GRISM/PRISM PERFORMANCE ACS26 - ACS RAMP FILTER TEST ACS12 - HRC CORONOGRAPHIC ACQ WFC FLAT FIELD STABILITY ACS22 - SBC DARK CURRENT MEASUREMEN 4/ ACS23 - SBC PSF & IMAGE QUALITY ACS24 - SBC FLAT FIELD UNIFORMITY ACS27 - SBC GEOM'T'C DISTORTION 35 PRD/FSW UPDATES ACS25 - HRC COR'GR'C SCATTERED LIGHT 10 ACS SBC AND FULL CCD SCIENCE ENABLE ACS CORONOGRAPHIC EROs ACS17 - ACS POINTING STABILITY ACS10 (SBC) CONTAM MONITOR 5/29 6/3 Page 7

12 SMOV3B TIPS 02May02 Carl Biagetti NICMOS SMOV SCHEDULE March April May June July August ID Task Name Duration 2/24 3/3 3/10 3/17 3/24 3/31 4/7 4/14 4/21 4/28 5/5 5/12 5/19 5/26 6/2 6/9 6/16 6/23 6/30 7/7 7/14 7/21 7/28 8/4 8/11 3 SM3B MISSION 12 days 2 BRIGHT EARTH AVOIDANCE (BEA) 12 days 1 HST RELEASE 0 days 3/9 41 NCS FILL PROCEDURE 2 hrs V1 NCS01 START NCS CPL 0.3 days 6 NICMOS SAFED 0 days NCS01 NCS ACTIVATION & NICMOS COOLDOW 0 days 3/18 3/ NCIMOS10 - NICMOS COOLDOWN DARKS 8 days 42 BEA COMPLETE 0 days 3/21 5 NICMOS COOLDOWN COMPLETE 0 days 4/13 7 NICMOS TO OPERATE 0 days 4/ NCIMOS10 - NICMOS COOLDOWN DARKS - PA 22 days NICMOS01 FW TESTS 10 days NICMOS03 - FLATS & QE 5 days 13 NICMOS TEMP SET POINT ADJUST 7 days 39 FILTER WHEELS ENABLED 0 days 5/ NICMOS06/07 - FINE OPT ALIGN 7 days NICMOS02 FOM OPTICAL OPERATION TEST 1 day 10 NICMOS TEMP SET POINT TECH REVIEW 0 days 9 NICMOS TEMP SET POINT ESTABLISHED 0 days UPLINK ALIGN/TILT PARAMS 0 days 18 NICMOS GO SCIENCE ENAB (BASIC MODES) 0 days 5/7 5/9 5/10 5/ NICMOS18 - THERMAL BACKGROUND 1 day NICMOS18 - PARALLEL THERMAL B/G 60 days 4 NICMOS EROs 6 days NICMOS10 - APERTURE LOCATIONS 1 day NICMOS05 - TRANSFER FUNCTION TEST 1 day NICMOS17 - ASTROM'C PERS'T'CE MEAS 1 day NICMOS04 - DET NOISE, SHADING, & CRs 1 day NICMOS20 - GRISM WAVELENGTH CAL 5 days NICMOS14 - FLAT FIELDS 1 day NICMOS15 - PHOTOMETRY 6 days NICMOS16 - CR PERSISTENCE 1 day NICMOS11 - PLATE SCALE 1 day NICMOS09 - FOCUS MONITOR 1 day 20 PRD SIAF, GAIN TABLE, ROT MATRIX UPDATES 1 day 6/ NICMOS12 - MODE2 TRG ACQ 1 day NICMOS09B - FOCUS MONITOR 1 day 31 PDB SIAF U/D & PATCHABLE CONSTS (512) 1 day 7/ NICMOS08 - COR'GRAPHIC FOCUS 1 day NICMOS13 - CORONOGRAHIC PERFORMANCE 1 day 38 NICMOS C'R'G'PH'C SCI ENABLED 0 days Page 8 8/

13 TIPS 2 May 2002 Adam Riess ACS Update ERO s!!! (Ford and the IDT) Max Mutchler and daughter doing well after kidney servicing mission SMOV programs have been initiated or scheduled, except SBC, some GO SBC high voltage to be turned on next week (after electronics outgassing) Software Issues: updates to calacs from IDT (Hack) Second Anneal (Cox) occured on April 28th: for HRC ~80% anneal, for WFC ~45% anneal (Riess). CR analysis: similar to WFPC2 (Riess) Photometric anomalies at the ~10% level (Gilliland, DeMarchi, et al) HRC is ~5% less sensitive than ETC, exceptions 330W -20%, 850LP -25% WFC is ~10-15% more sensitive than ETC (except F850LP -5%), WFC

14 TIPS 2 May 2002 Adam Riess photometry field dependence WFC Hot Pix Growth 2nd Anneal~50% new ~22% old 1st Anneal ~45%

15 TIPS 2 May 2002 Adam Riess typical CR coverage hot pixel growth

16 TIPS 2 May 2002 Adam Riess Cosmic Ray Characteristics e per event attached pixels per event

17 Torsten Böker TIPS May 2, 2002 NICMOS post-cooldown detector performance 1) SMOV status 2) Dark current 3) Quantum efficiency 4) First light, focus and image quality 5) SMOV outlook

18 Thermal history since NICMOS switch-on (on April 19) Transition to detector control Transition to Ne control Setpoint to 72.5 K Setpoint to 72 K

19 X X X X

20 Filter wheel test (G. Schneider, K. Noll, L. Mazzuca, E. Roberts) - NICMOS filter wheels have motion sensor only on the motors, not on the wheels themselves - Concern about breaking the wheel shaft in case of mechanical contact/blockage - careful two step forward, one step back approach with analysis of motor currents and flat field images - so far, so good: verified normal motion over 9/10 of a full turn - side benefit: early measurement of DQE (and more.)

21 NICMOS dark current (C. Xu) -preliminary measurements indicate that dark current is nominal, i.e. close to Cycle 7 - bump is NOT observed Mean: /s Mean: e - e/s - /s

22 The first flat field images Then (1998, T=62 K) Now (2002, T= 77K) NIC1 NIC2 NIC3

23 DQE comparison with expectations

24 Serendipitous image of a crowded star field ( taken out from electronic distribution as requested by HST project ) Camera 2 in H-band (F160W) FWHM: 2.17 pixels (0.163 ) (very close to nominal!)

25 First assessment of image quality: (G. Schneider) -VERY close to nominal focus - some coma, to be corrected with tilt adjustment of PAM (in time for ERO observations) Mean PSF from 2002 stellar field (NIC1, F095N) 1997 PAM tilt grid (NIC1, F095N)

26 NICMOS SMOV: early activities timeline 4/19 Fri 4/22 Mon 4/23 Tue 4/26 Fri 4/29 Mon 4/30 Tue 5/02 Thu 5/03 Fri 5/04 Sat 5/06 Mon 5/08 Thu 5/10 Sat 5/16 Fri NICMOS restarted, Ne-loop control continues Change to mounting cup control Return to Ne control, Filter wheel test begins Increase control temperature to allow for seasonal margins +2 K Begin darks every 3 rd orbit DQE test visit 1; Control temp +0.5 K DQE test visit 2; Control temp 1.0 K Filter wheel test complete; Focus sweep, FOM test, Transfer function test DQE test visit 3; Control temp +0.5 K (TBD) DQE test visit 4; Stop darks Final temperature set point (TBD) EROs begin, flats, thermal background Final focus update, GO science enabled, remaining SMOV begins

27 Torsten Böker TIPS May 2, 2002 Summary - NICMOS has survived its 28 month hiatus without any significant degradation - performance is nominal so far - GO science will be enabled within 2 weeks

28 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 1 Wide Field and Planetary Camera 2 WFPC2 SMOV3B Results UV Contamination Monitoring Far-UV / Lyman-Alpha Verification Photometric Filter Throughput PSF Verification Internal Monitoring Flat-Field Stability WFPC2 Cycle 11 Calibration Plan

29 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 2 WFPC2 SMOV3B UV Contamination Monitoring (Koekemoer, Gonzaga, Lubin, Whitmore, Heyer) Aim: Monitor rates of contaminants deposited on the cold (-88 o C) CCD windows of each camera, and ensure that the total drop in throughput at F170W never exceeds 30%. Observations: Observed the usual WFPC2 standard star GRW+70d5824 at F170W, starting immediately after cooldown to -88 o C (on 23 March 2002), then subsequently at 3, 6, 18, 24, 36 hours, and 2, 3, 4, 5, 6 days after the cooldown. Also obtained F170W observations before and after each subsequent DECON procedure, at 7, 14 and 28 days after cooldown.

30 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 3 Results: Total throughput at F170W was always above 85-90% (thus safely above the critical 70% threshold limit) Each DECON procedure successfully returned throughput to the pre- SMOV3B values Contamination rates are now comparable to pre-smov3b values Note: Overall contamination rates have decreased since 1995 epochs reduction of vapor-phase contaminants inside the cameras? possible slow escape of contaminants over time?

31 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 4 WFPC2 SMOV3B Far-UV Lyman-Alpha Verification (Lubin, Whitmore, Koekemoer) Aim: Measure the Far-UV throughput (at Lyman-alpha) to determine whether there is any decrease resulting from contaminants deposited on the pickoff mirror / OTA surfaces. Observations: GRW+70d5824 with the PC and WF3 cameras, using: F122M filter in isolation, and crossed with F130LP to eliminate the red-leak component F160BW filter in isolation, and crossed with F130LP, to provide a longer-wavelength comparison Results: No significant departures from the long-term throughput behavior (to within ~5-6% measurement uncertainties)

32 F122M TIPS: 2 May 2002 WFPC2 Anton Koekemoer F160BW 5

33 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 6 WFPC2 SMOV3B Photometric Throughput Verification (Whitmore, Heyer) Aim: Measure throughput of a variety of commonly used WFPC2 photometric filters covering a wide range of wavelengths. Observations: Observe the standard star GRW+70d5824 in: F160BW, F170W, F185W, F218W, F255W, F300W, F336W, F439W, F555W, F675W, F814W Results: No significant changes from long-term trends to within the measurement accuracy (~1-2% for most filters)

34 PC WF2 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 7

35 WF3 WF4 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 8

36 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 9 WFPC2 SMOV3B PSF Verification (Lubin, Kozhurina-Platais, Koekemoer) Aim: Verify whether or not the Point-Spread Function properties of WFPC2 have changed after SM3B Observations: Rich star field (Omega Cen) in F555W Use the data to construct an average empirical PSF Results: No significant change in PSF properties compared to before SM3B

37 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 10 Pre-SM3B: Relative Intensity FWHM=0."064 Post-SM3B: PC Pixels

38 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 11 WFPC2 SMOV3B Internal Monitoring (Koekemoer, Kozhurina-Platais, Gonzaga) Aim: Quantify any changes in the behavior of the detector electronic after SM3B: dark current bias properties read-noise gain ratio Also observe K-spots to measure possible changes in camera positions Results: no statistically significant changes in any of the 4 chips for dark current, bias level, read-noise or gain ratio Slightly cleaner bias structure in WF4 post-sm3b ( no more ripples )

39 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 12 Dark Current (e - /s/pixel) Pre-SM3B Post-SM3B PC / / WF / / WF / / WF / / Read-noise (e - ) Gain Pre-SM3B Post-SM3B PC / / WF / / WF / / WF / / PC / / WF / / WF / / WF / /- 0.24

40 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 13 WFPC2 SMOV3B Flat Field Verification (Koekemoer, Heyer) Aim: Determine whether there are any changes in the total light path after SM3B Observations: Exposures of the bright earth ( earthflats ) in a range of narrow-band filters: F375N, F502N, F656N, F953N Results: No significant changes in the large-scale flat field structure (to within levels ~ %)

41 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 14 Ratio of Earthflats Pre-SM3B / Post-SM3B (F502N; linear greyscale, covering +/- 2%) streakflat_f502n_rat o_mos STREAKFLAT_F502N_RATIO_MOS[1/1] z1=0.98 z2=1.02 ztrans=linear Con=1.00 Brt=0.50 cmap=grayscale ncolors=

42 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 15 WFPC2 Cycle 11 Calibration Plan (Gonzaga, Koekemoer, Whitmore, + WFPC2 Group) Maintain calibration via monitoring programs. Continue some special programs from previous cycles. Perform a few new tests. Look for areas to cut orbits (Note: Used 61 external orbits in Cycle 10) Total (through August 1, 2003): 40 External orbits 2171 Internals (occultations) Type External Orbits Internals (Occultations) Monitors: decons, darks, internals, Earthflats, UV & VISFlats Continuation/New Special Programs 17 1 Reserve (Unexpected Items) 3 Total

43 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 16

44 Monitoring Programs TIPS: 2 May 2002 WFPC2 Anton Koekemoer 17 WFPC2 Decons and Associated Observations Many programs combined into one, because they are linked to decons, to minimize scheduling problems. Decontaminations - remove contaminants, anneal hot pixels. Photometric Monitoring - Verify decon success & monitor long-term trends. - 1 orbit after each decon, 1 orbit before every other decon. - Use different primary chip each month. - GRW+70d5824 in standard broad band filters. - Match accuracy of trending in previous cycles: ~1-2%.

45 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 18 WFPC2 Decons and Associated Observations (cont d) Internal Monitoring to Verify Instrument Health and Generate CDBS files. UV Photometric Throughput Check (run once in cycle) - Verify throughput in UV filters not included in photometric monitor. - Use to update Synphot. VISFLAT Mini-sweep and UV Flat Check (run once in cycle) - Monitor flatfield stability with cal channel lamp. Total of 20 external orbits: 13 for photometric monitoring (8 decons), 5 for UV throughput, 2 orbits for internal UV flats. Darks - Standard darks, 1800 sec each, 6/week during non-decon week. - Continue supplemental darks: 0-3/day, 1000s, low priority, for archive only. (Note: Willing to cut back on these if overall data volume is an issue for archive.)

46 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 19 Internal Monitor - Biases, intflats for monitoring instrument stability during non-decon weeks. - Provides internals for generation of CDBS files. Intflat Sweeps and Linearity Test - Intflat sweep: most filters, both blades and gains. Monitor health. - Continued emphasis on INTFLATS (minimizing VISFLATS to spare lamp). - Monitor pixel to pixel flatfield response and cal channel lamp degradation. - Continue VISFLAT/INTFLAT/Earthflat check for filter wheel rotation problems. Earthflats - UV and Visible - Streak flats in subset of filters: general strategy of previous cycles followed. - Used to generate superflats which are used to produce pipeline flats. - Track & correct changes in flats.

47 Special Programs TIPS: 2 May 2002 WFPC2 Anton Koekemoer 20 Astrometric Monitor - Goal is to measure any shifts of chip position (~1 pixel shift evident since mid- 1994) or changes in astrometry within a chip. - Rich field in Omega Cen in F555W plus internal K-spot images - Run once in cycle (used to be 2x/cycle) - Expect to measure to at least 0.01" in relative shifts. CTE Characterization - Goal is to continue to monitor CTE degradation, better characterize the long-vsshort anomaly, and test whether 2x2 binning can reduce CTE. - Monitor to be executed once in cycle. Preflash test removed so only takes 1 orbit. - Same structure as before for monitors: Omega Cen in F814W and F555W, in WF2 & WF4, gain 7 and some gain 15.

48 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 21-2x2 Binning to see whether this reduces the CTE effect. This may be relevant for future ACS observations. 1 orbit. Similar observing strategy as CTE monitor. - High S/N Long vs. Short test for uncrowded field will be added. Recent indications are that the long vs. short effect is primarily relevant for very crowded fields. A higher S/N set of observations, i.e. with 10 repeats for the 10s exposures, are needed to determine whether the long vs. short effect is zero for uncrowded fields. 3 orbits.

49 TIPS: 2 May 2002 WFPC2 Anton Koekemoer 22 Photometric Characterization - Goal is to verify stability to 1-2%, and to update the photometric zeropoints in SYNPHOT. - GRW+70d5824 observed in all 4 detectors using selected non-standard filters that were not included in the UV throughput test (in photometic monitor program). - To be compared to baseline observations to identify any time dependencies. WFPC2-ACS Photometric Cross-Calibration - Establish cross-correlation with ACS to ~1% for all heavily-used broad-band filters (e.g. Johnson-Cousins and Sloane filters) - Observations to be done are 1. the primary ACS standard star, 2. two globular clusters spanning a wide range in metallicity (NGC 2419 and 47 Tuc, 3. observations of a Sloan Standard Field.

50 MEMORANDUM TO: Distribution DATE: May 2, 2002 SUBJECT: Questions and Answers from May 2, 2002 TIPS Meeting SISD Perspective Presenter Harry Ferguson Comment: The parallel working group will be meeting here on May 14 th. SMOV3B Update Presenter Carl Biagetti Q: When will we have the SMOV close out review? A: The SMOV close out review will probably be scheduled around September. ACS Update Presenter Adam Riess Q: What is the limiting magnitude for the ACS ERO image of UGC 10214? A: The limiting magnitude is about 0.5 magnitude less than HDF, which is ~28 th magnitude for 10 sigma detection. Q: Regarding the projection of hot pixels over time for ACS, how does ACS compare to WFPC2 and STIS? How are hot pixels defined in this analysis? A: For ACS fewer hot pixels are being fixed by the annealing than is the case for STIS. At the moment the analysis parameters (e.g. number of electrons required to call a pixel hot ) are not identical for the different instruments. More detailed comparisons will be forthcoming. Q: Could the observed field dependency of the photometric measurements be accounted for by applying radial and/or spatial aperture corrections? A: The radial and/or spatial aperture correction effects are weak, and look like they go in the sense of increasing the discrepancy. Q: Are there more long cosmic rays events in ACS than in WFPC2? A: Theory says there ought to be because the ACS uses thicker CCD chips. The visual impression is that the cosmic-rays are not dramatically different (not lots more long ones). NICMOS Update Presenter Torsten Boeker Q: What would be the range of the ultimate set point temperature for NICMOS? A: We are still looking into the possible range at this time, and we do not want to adjust the set point too often. The final set point will probably be about 77±0.5K. 1

51 Q: Since the dark current is lower than before, do we expect it to come back up? A: No, we do not expect drastic change in the dark current. Q: What is the speed margin for NCS and do we have the margin for further cooling? Do we expect the NCS to degrade over time? A: A change of 100rps for the compressor roughly corresponds to a change of 2K. The compressor is currently running close to the maximum speed now, and we do not expect to have a lot of margin for further speed increase. According to the manufacturer, the NCS performance is not expected to degrade over time. Q: On the graph showing the temperatures of the different sensors, what are the causes of the temperature fluctuations seen right after we switch back to Ne control? A: HST went to a relatively hot attitude after the switch back to Ne control, and that may have put more load on the system. WFPC2 Update Presenter Anton Koekemoer Q: During this SMOV, WFPC2 was kept warm longer. Are there any noticeable effects on the instrument? A: No, nothing significant has been observed. Q: Were the CTE effects taken out for the study of the long-term throughput? A: No, the data shown were not corrected for the CTE effects. There are two components affecting the long -term throughput trends: one is the CTE effect and the other is contamination. This second effect is most significant in the UV. We will need to update synphot to account the long-term contamination trend. 2