Telescope and Instrument Performance
Summary (TIPS)
2 May 2002
AGENDA
1.
2.
3.
4.
5.
SISD Perspective
SMOV3B Update
ACS Update
NICMOS Update
WFPC2 Update
Harry Ferguson
Carl Biagetti
Adam Riess
Torsten Boeker
Anton Koekemoer
Next TIPS Meeting: 16 May 2002
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
Cross-instrument activities
• Calibration workshop
– 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
May all your anomalies be minor…
2 May 2002
H. Ferguson TIPS
3
TIPS 02May02
Carl Biagetti/NISD
SMOV3B
SMOV3B
PROGRESS
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
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
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
TIPS 02May02
Carl Biagetti
SMOV3B
SMOV PROGRESS AS OF 01 MAY
PLANNED
ACTIVITIES
COMPLETED
ACTIVITIES
PERCENT
COMPLETE
SPACECRAFT
20
20
100.0
ACS
30
17
56.7
ERO
3
1
33.3
NCS
2
1.5
75.0
NICMOS
21
2
9.5
STIS
10
10
100.0
WFPC
TOTAL
7
7
100.0
======= ======= ======= ======= =======
93
58.5
62.9
Page 5
SMOV3B
TIPS 02May02
Carl Biagetti
MAJOR SMOV MILESTONES
UPDATED AS OF 01 May
Release
09 March
NICMOS Cooldown
18 Mar – 12 Apr
STIS Basic CCD GO Science
22 March
WFPC2 Cooldown
22 March
WFPC2 GO Science
26 March
ACS ALIGN
22 March – 2 April
5 days ahead of plan
ACS CCD EROs
01-09 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)
03 - 09 May
~ 4 week delay
NICMOS EROs
10 - 16 May
~ 2 week delay
NICMOS Basic GO Science Enable
10 May (approx.)
~ 2 week delay
(17 day 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
TIPS 02May02
Carl Biagetti
SMOV3B
ACS SMOV SCHEDULE
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 WT F S S M T W T F S S M TW T F S S M T W T F S S M TW T F S S M T W T F S S M T W T F S S M TW T F S S M T W T F S S M TW T F S S M T W T F S S M T WT
ID
38
Task Name
HST RELEASE
2
9002 ACS02 - ACS LOAD & DUMP ON-BOARD MEM
3
9003 ACS03 - ACS SCIENCE DATA BUFFER CHEC
36
9006 ACS06 - ACS CCD TEMP SET POINT DETER
4
9005 ACS05 - ACS CCD FUNCTIONAL
31
8947 ACS05 ACS DAILY TEST
34
9013 ACS13 - ACS COARSE ALIGNMENT
29
9031 ACS31 - ACS CCD HOT PIXEL ANNEALING
33
9014 ACS14 - ACS FINE ALIGNMENT
1
9574 HST FOCUS MON (WFPC2/ACS/STIS)
37
8992 ACS EROs
28
ACS BASIC CCD SCIENCE ENABLE
8
9011 ACS11 - ACS/FGS ALIGNMENT
12
9015 ACS15 - ACS IMAGE QUAL & PSF MEAS
26
9028 ACS28 - ACS CCD GEOMETRIC DISTORTIO
30
8948 ACS05 ACS CTE TEST
32
9032 ACS32 - ACS CCD PRE-FLASH TEST
7
9010 ACS10 - HRC CONTAM MONITOR
13
9016 ACS16 - HRC COR'GR'IC REPEATABILITY
17
9020 ACS20 - ACS SENSITIVITY
15
9019 ACS18/19 - HRC FF STABILITY
5
9008 ACS08 - SBC ACTIVATION
9
PRD SIAF UPDATE
6
9009 ACS09 - SBC FOLD ANALYSIS FOR ANOM R
25
9029 ACS29 - ACS GRISM/PRISM PERFORMANCE
24
9026 ACS26 - ACS RAMP FILTER TEST
11
9012 ACS12 - HRC CORONOGRAPHIC ACQ
16
9018 WFC FLAT FIELD STABILITY
18
9022 ACS22 - SBC DARK CURRENT MEASUREMEN
20
9023 ACS23 - SBC PSF & IMAGE QUALITY
21
9024 ACS24 - SBC FLAT FIELD UNIFORMITY
27
9027 ACS27 - SBC GEOM'T'C DISTORTION
35
PRD/FSW UPDATES
22
9025 ACS25 - HRC COR'GR'C SCATTERED LIGHT
10
ACS SBC AND FULL CCD SCIENCE ENABLE
23
8992 ACS CORONOGRAPHIC EROs
14
9017 ACS17 - ACS POINTING STABILITY
19
9010 ACS10 (SBC) CONTAM MONITOR
3/9
4/2
4/28
5/29
6/3
Page 7
TIPS 02May02
Carl Biagetti
SMOV3B
NICMOS SMOV SCHEDULE
March
ID
3
Task Name
SM3B MISSION
Duration
12 days
2
BRIGHT EARTH AVOIDANCE (BEA)
12 days
1
HST RELEASE
0 days
41
NCS FILL PROCEDURE
2 hrs
40
8967V1 NCS01 START NCS CPL
0.3 days
6
NICMOS SAFED
0 days
8
8967 NCS01 NCS ACTIVATION & NICMOS COOLDOW0
days
14
8945 NCIMOS10 - NICMOS COOLDOWN DARKS
8 days
42
BEA COMPLETE
0 days
5
NICMOS COOLDOWN COMPLETE
0 days
7
NICMOS TO OPERATE
0 days
2/24
3/3
April
3/10
3/17
3/24
3/31
May
4/7
4/14
4/21
4/28
5/5
June
5/12
5/26
6/2
July
6/9
6/16
6/23
6/30
August
7/7
7/14
7/21
7/28
8/4
8/11
3/9
3/18
3/18
3/21
4/13
4/19
12
8945 NCIMOS10 - NICMOS COOLDOWN DARKS - PA 22
35
8944 NICMOS01 FW TESTS
10 days
36
8974 NICMOS03 - FLATS & QE
5 days
13
NICMOS TEMP SET POINT ADJUST
7 days
39
FILTER WHEELS ENABLED
0 days
15
8977 NICMOS06/07 - FINE OPT ALIGN
7 days
37
8973 NICMOS02 FOM OPTICAL OPERATION TEST
1 day
10
NICMOS TEMP SET POINT TECH REVIEW
0 days
9
NICMOS TEMP SET POINT ESTABLISHED
0 days
5/9
11
8977 UPLINK ALIGN/TILT PARAMS
0 days
5/10
18
NICMOS GO SCIENCE ENAB (BASIC MODES)
0 days
5/10
28
9269 NICMOS18 - THERMAL BACKGROUND
1 day
29
9269 NICMOS18 - PARALLEL THERMAL B/G
60 days
NICMOS EROs
6 days
32
8981 NICMOS10 - APERTURE LOCATIONS
1 day
34
8976 NICMOS05 - TRANSFER FUNCTION TEST
1 day
23
8988 NICMOS17 - ASTROM'C PERS'T'CE MEAS
1 day
27
8975 NICMOS04 - DET NOISE, SHADING, & CRs
1 day
24
8991 NICMOS20 - GRISM WAVELENGTH CAL
5 days
22
8985 NICMOS14 - FLAT FIELDS
1 day
25
8986 NICMOS15 - PHOTOMETRY
6 days
26
8987 NICMOS16 - CR PERSISTENCE
1 day
33
8982 NICMOS11 - PLATE SCALE
1 day
16
8980 NICMOS09 - FOCUS MONITOR
1 day
20
PRD SIAF, GAIN TABLE, ROT MATRIX UPDATES
1 day
19
8983 NICMOS12 - MODE2 TRG ACQ
1 day
17
8980 NICMOS09B - FOCUS MONITOR
1 day
31
PDB SIAF U/D & PATCHABLE CONSTS (512)
1 day
30
8979 NICMOS08 - COR'GRAPHIC FOCUS
1 day
21
8984 NICMOS13 - CORONOGRAHIC PERFORMANCE
1 day
38
NICMOS C'R'G'PH'C SCI ENABLED
0 days
4
5/19
days
5/2
5/7
6/7
7/3
8/
Page 8
SPACE TELESCOPE SCIENCE INSTITUTE
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
•
•
•
•
•
•
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS
2 May 2002
Adam Riess
photometry field dependence
WFC Hot Pix Growth
1st Anneal ~45%
2nd Anneal~50% new
~22% old
SPACE TELESCOPE SCIENCE INSTITUTE
typical CR coverage
h
wth
o
r
g
l
e
ot pix
TIPS
2 May 2002
Adam Riess
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS
2 May 2002
Adam Riess
Cosmic Ray Characteristics
e per event
attached pixels per event
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
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
X
X
X
X
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….)
NICMOS dark current
(C. Xu)
-preliminary measurements
indicate that dark current is
nominal, i.e. close to Cycle 7
- “bump” is NOT observed
Mean: 0.166 e--/s
Mean:0.114
0.148e-e/s/s
Mean:
The first flat field images
Then…
(1998, T=62 K)
Now…
(2002, T= 77K)
NIC1
NIC2
NIC3
DQE – comparison with expectations
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!)
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)
NICMOS SMOV: early activities timeline
4/19 Fri
109
NICMOS restarted, Ne-loop control continues
4/22 Mon
112
Change to mounting cup control
4/23 Tue
113
Return to Ne control, Filter wheel test begins
4/26 Fri
116
Increase control temperature to allow for seasonal margins +2 K
4/29 Mon
119
Begin darks every 3rd orbit
4/30 Tue
120
DQE test visit 1; Control temp +0.5 K
5/02 Thu
122
DQE test visit 2; Control temp –1.0 K
5/03 Fri
123
Filter wheel test complete; Focus sweep, FOM test, Transfer function test
5/04 Sat
124
DQE test visit 3; Control temp +0.5 K (TBD)
5/06 Mon
126
DQE test visit 4; Stop darks
5/08 Thu
129
Final temperature set point (TBD)
5/10 Sat
131
EROs begin, flats, thermal background
5/16 Fri
137
Final focus update, GO science enabled, remaining SMOV begins
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
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
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
1
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
WFPC2 SMOV3B UV Contamination Monitoring
(Koekemoer, Gonzaga, Lubin, Whitmore, Heyer)
Aim:
• Monitor rates of contaminants deposited on the cold (-88o 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 -88o 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.
2
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
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 preSMOV3B 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?
3
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
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)
4
SPACE TELESCOPE SCIENCE INSTITUTE
F122M
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
F160BW
5
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
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)
6
SPACE TELESCOPE SCIENCE INSTITUTE
PC
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
WF2
7
SPACE TELESCOPE SCIENCE INSTITUTE
WF3
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
WF4
8
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
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
9
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
SPACE TELESCOPE SCIENCE INSTITUTE
Pre-SM3B:
1.0
Relative Intensity
FWHM=0."064
0.8
0.6
0.4
0.2
0.0
0.0
Post-SM3B:
0.5
1.0
PC Pixels
1.5
2.0
10
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
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”)
11
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
Dark Current (e-/s/pixel)
Pre-SM3B
Post-SM3B
PC
0.0072 +/- 0.0007
0.00727 +/- 0.0017
WF2
0.0051 +/- 0.0005
0.00448 +/- 0.0018
WF3
0.0068 +/- 0.0007
0.00676 +/- 0.0019
WF4
0.0063 +/- 0.0006
0.00637 +/- 0.0017
Read-noise (e-)
Gain
Pre-SM3B
Post-SM3B
PC
7
5.48 +/- 0.02
5.36 +/- 0.03
WF2
WF3
WF4
PC
WF2
WF3
WF4
7
7
7
15
15
15
15
5.23 +/- 0.01
5.21 +/- 0.05
5.24 +/- 0.01
7.76 +/- 0.04
7.90 +/- 0.13
7.70 +/-0 .14
7.88 +/- 0.39
5.38 +/- 0.06
5.26 +/- 0.08
5.33 +/- 0.13
7.79 +/- 0.25
7.47 +/- 0.24
8.27 +/- 0.17
8.52 +/- 0.24
12
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
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 ~0.3 - 0.5%)
13
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
SPACE TELESCOPE SCIENCE INSTITUTE
Ratio of Earthflats Pre-SM3B / Post-SM3B
(F502N; linear greyscale,
covering +/- 2%)
streakflat_f502n_rat o_mos STREAKFLAT_F502N_RATIO_MOS[1/1]
1600
1400
1200
1000
0
500
1000
1500
z1=0.98 z2=1.02 ztrans=linear Con=1.00 Brt=0.50 cmap=Grayscale ncolors=166
0
0
0
1
1
1
14
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
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)
External
Orbits
Internals
(Occultations)
Monitors: decons, darks, internals, Earthflats, UV & VISFlats
19
2170
Continuation/New Special Programs
17
1
Reserve (Unexpected Items)
3
Total
40
Type
2171
15
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
16
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
Monitoring Programs
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%.
17
SPACE TELESCOPE SCIENCE INSTITUTE
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.)
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
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.
19
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
Special Programs
Astrometric Monitor
- Goal is to measure any shifts of chip position (~1 pixel shift evident since mid1994) 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.
20
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
- 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.
21
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 2 May 2002
WFPC2
Anton Koekemoer
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.
22
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 14th.
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 ~28th 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
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