HST
MOSES
WFPC2 Activities in
SMOV3B
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
GOALS:
•
Maintain WFPC2 health and safety by avoiding excessive exposure to UV
contamination
•
Streamline WFPC2 activities
•
Return WFPC2 to science as soon as practical
OUTLINE:
•
Keep WFPC2 in protect safe/protect decon throughout BEA period
•
Cool down directly to –88 C after end of BEA
•
Frequent UV observations soon after cooldown (0, +3, +6, +12, +18, +24,
+36 hours, then daily for first week)
•
Second decon 1 week after cooldown
•
Science enabled after first day of UV contamination observations, may be
delayed because of scheduling constraints
HST
MOSES
•
WFPC2 during BEA
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
Unlike previous servicing missions, WFPC2 will be kept warm during BEA
– Increased contamination rate in SMOV3a during BEA (up to 2.5% /
day); could be higher with new instruments
– Turning on WFPC2 during BEA increases resource requirements:
• Need to identify, pre-observe targets in BEA (5 to 10, depending
on launch date)
• Two-step cooldown needed
• More rapid turnaround observations, more contingency paths
• More WFPC2 orbits needed, might delay other instruments
– No targeted science possible during BEA
HST
MOSES
Summary of activities
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
Activity
ID
Short title
Orbits (externals)
Hours (internals)
Applicable
requirements
Notes
WFPC2-01
Transition to Hold and
to Protect Decon
20 hours + 7 days in
protect decon
J.10.4.1.1.1
Occurs after Health and
Safety SMS
WFPC2-03
Cool Down,
Contamination Monitor,
and Focus Check
21 orbits
50 hours
J.10.4.1.1.2
J.10.4.1.1.3
UV data must be available
within 6 hours for first day,
12 hours in first week
WFPC2-04
Lyman α check
1 orbit
J.10.4.1.2.2
No plan to return to BEA
WFPC2-05
Flat field calibration
10 hours
J.10.4.1.2.3
Earth flats
WFPC2-06
Relative photometry
calibration
4 orbits
J.10.4.1.2.2
Shortly after decon
WFPC2-07
PSF verification
3 orbits
J.10.4.1.2.1
J.10.4.1.2.4
To be repeated if NCS
startup is delayed
WFPC2-08
Internal monitors (nondecon weeks)
2 orbits (for UV flats)
24 hours
J.10.4.1.2.3
HST
MOSES
•
•
•
Contingencies
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
UV contamination > 30% (plan prepared by Colleen Townsley):
– Place instrument in protect decon via real-time commanding
– If needed, set safing flag to prevent execution of observations
– Replan following SMS to repeat cooldown procedure
– Procedure maintains instrument safe while minimizing disruption for
other instruments
– Script with real-time procedures prepared and tested before SMOV
Delay in NCS startup:
– Must repeat PSF test after NCS startup (prepared but not scheduled)
Lyman α contamination (pick-off mirror): No action planned if < 20%
– Zero Lyman α science with WFPC2
– Better Lyman α imagers on board (STIS FUV MAMA and ACS SBC)
– OTA contamination verified by STIS
– High contamination (very unlikely) to be evaluated at the time
HST
MOSES
WFPC2-01
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
ACTIVITY TITLE: WFPC2 Transition from Protect Safe Mode to Hold Mode, to
Protect Decontamination Mode
APPLICABLE SMOV REQUIREMENT: J.10.4.1.1.1
DESCRIPTION: Recover WFPC2 from Protect Safe to Hold. Configure power
relays, clear and reset safing status bits, enable and execute application
processor limit checking, turn LVPS on, initialize microprocessor, select
SDF I/F, enable microprocessor idle checking and bay 1 temperature
control. After transitioning to Hold, begin real-time microprocessor
memory collection for PROM and RAM. SMS has an appropriate wait time
for RAM dump and verification. After RAM validation and while WFPC2 is
in Hold mode, initiate Protect decontamination transition. Enable CCD
heaters on, position filter F785LP in optical path, close shutter blade A,
enable radiator heat pipe heaters on.
DEPENDENCIES: Completion of SM3B activities
DURATION: 20 Hours
DATA REQUIREMENTS: Availability of serial telemetry data, and RAM and
PROM memory dumps.
HST
MOSES
WFPC2-01 (cont)
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
ANALYSIS:
Perform engineering matrix verification (commanding, application
processors, microprocessor, mechanism, and error messages)
Perform dump and miscompares on RAM and PROM data
Monitor thermal and power performances
Monitor camera decontamination thermal profile.
RESULTS:
Verify nominal operation of WFPC2
Place WFPC2 in protective decontamination state with CCD camera
temperatures at +22 C.
NOTE: Proposal due to Sito Balleza
HST
MOSES
•
•
WFPC2-02
Placeholder for temperature drop to –55 C
Activity no longer used
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
HST
MOSES
WFPC2-03
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
ACTIVITY TITLE: WFPC2 Cool Down, Contamination Monitor, and Focus
Check
APPLICABLE SMOV REQUIREMENT: J.10.4.1.1.2, J.10.4.1.1.3
DESCRIPTION: After 24 hours in Protect Decon mode (Activity WFPC2-01), the
camera is cooled down to the standard operating temperature of -88C.
The cool down is timed to end shortly after the end of the BEA
restrictions. The expected growth of UV contamination is monitored with
observations of a standard star, initially very frequent, then progressively
less frequent as better information on the contamination monitor is
obtained. UV monitoring observations will be taken at 0, 3, 6, 12, 18, 24, 36,
and 48 hours, 3, 4, 5 and 6 days from the end of cool down. The camera
will undergo planned decontamination procedures (PROTECT DECONs) 7,
14, and 28 days after cool down. Observations include a set of internals
(darks, biases, INTFLATs, KSPOTs) after the initial cooldown and after
each decontamination. The focus check consists of three separate sets of
F555W observations of the standard star, starting shortly after cooldown
and spaced by about 24 hours.
HST
MOSES
WFPC2-03 (cont)
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
DEPENDENCIES: WFPC2-01; End of BEA
DURATION: Total of 21 external orbits, 50 hours of internals
DATA REQUIREMENTS: 260 images
ANALYSES & RESULTS:
Trend UV throughput (expected accuracy better than 1% per epoch)
Verify photometry before and after each decon
Determine contamination rates
Measure focus position using phase retrieval
COMMENTS:
WFPC2 is enabled for science observations after 24h of UV monitoring.
IMPORTANT:
UV monitoring data within the first 24 hours after cooldown must be
delivered within 6 hours and analyzed within 12 hours. UV monitoring
data in first week, focus data must be delivered within 12 hours.
If contamination resulting in loss of 30% of the UV throughput at F170W
triggers the WFPC2 UV contamination contingency plan.
HST
MOSES
WFPC2-04
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
ACTIVITY TITLE: WFPC2 Lyman α Check
APPLICABLE SMOV REQUIREMENT: J.10.4.1.2.2
DESCRIPTION: The WFPC2 primary standard GRW+70d5824 is observed in
the far UV with filters F160BW, F122M by themselves and crossed with
F130LP to assess Lyman α contamination. Measurements error ~ 5%.
IMPLEMENTATION METHOD: Proposal
DEPENDENCIES: WFPC2 enabled for science observations
DURATION: 1 external orbit
DATA REQUIREMENTS: 17 images
ANALYSES & RESULTS: The UV photometry is compared with pre-SMOV
measurements, both for the UV filters and for the UV filters crossed with
F130LP. Flux decrease in the UV observations, but not in the UV crossed
with F130LP, is indicative of Lyman α contamination.
COMMENTS: Because of the small impact of Lyman α observations on WFPC2
science, we do not plan a return to BEA if low-level contamination (<20%)
is detected.
HST
MOSES
WFPC2-05
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
ACTIVITY TITLE: WFPC2 Flat Field Calibration
APPLICABLE SMOV REQUIREMENT: J.10.4.1.2.3
DESCRIPTION: External (Earth) flat fields will be obtained for the four narrowband filters F375N, F502N, F656N, and F935N (20 images each) after the
end of the BEA phase.
DEPENDENCIES: WFPC2 enabled for science observations
DURATION: 10 hours, spread throughout SMOV
DATA REQUIREMENTS: 80 images
ANALYSES & RESULTS: Flat fields in each filter will be combined to remove
cosmic rays and streaks. Images will be compared with pre-SM3 images
to quantify stability and measure any changes that may have occurred.
Check for changes in flat field. Update pipeline flat field calibration (not a
prerequisite for further SMOV activities).
HST
MOSES
WFPC2-06
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
ACTIVITY TITLE: WFPC2 relative photometry calibration
APPLICABLE SMOV REQUIREMENT: J.10.4.1.2.2
DESCRIPTION: The WFPC2 primary standard GRW+70d5824 is observed
through F160BW, F170W, F185W, F218W, F255W, F300W, F336W, F555W,
F675W, and F814W in all four cameras.
DEPENDENCIES: WFPC2 enabled for science observations
DURATION: 4 orbits
DATA REQUIREMENTS: 44 images
ANALYSES & RESULTS: Aperture photometry will be performed on each
image to measure instrument response and throughput. Results will be
compared with historic pre-SMOV photometry results. Update pipeline
and database photometric tables if required; this is not a prerequisite for
further SMOV activities.
COMMENTS: Must execute shortly (1-2 days) after a decontamination.
HST
MOSES
WFPC2-07
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
ACTIVITY TITLE: WFPC2 Point Spread Function Verification
APPLICABLE SMOV REQUIREMENT: J.10.4.1.2.1, J.10.4.1.2.4
DESCRIPTION: Exposures over a wide dynamic range of a bright star through
a wide-band filter (F555W) will be obtained in order to characterize the
extended wings of the PSF. Exposures will also be made of a crowded
stellar field with sub-pixel stepping to provide a critically sampled PSF.
DEPENDENCIES: WFPC2 enabled for science observations
DURATION: 3 orbits
DATA REQUIREMENTS: 33 images
ANALYSES & RESULTS: The PSF will be reconstructed by DRIZZLE and
checked against both theoretical models (TinyTim) and pre-SMOV
observations. Linearity will be cehcked by comparing PSFs taken at
different count levels.
COMMENT: Proposal must be repeated if executed before NCS turn-on
(Requirement J.10.4.1.2.4)
HST
MOSES
WFPC2-08
SMOV3b PROJECT
REVIEW
25 Jan 2001
Stefano Casertano
WFPC2/STScI
ACTIVITY TITLE: WFPC2 Internal Monitors
APPLICABLE SMOV REQUIREMENT: J.10.4.1.2.3
DESCRIPTION: Routine internal observations will be obtained to monitor the
basic instrument health and its optical alignment via K-spot observations,
to verify the stability of the calibration and INTFLATs, and to check for
contamination. Weekly execution includes biases, darks, K-spots and
INTFLATs. One-time execution includes VISFLATs and UVFLATs.
DEPENDENCIES: WFPC2 enabled for science observations
DURATION: 24 hours of internals, 2 external orbits (for UVFLATs)
DATA REQUIREMENTS: 49 images
ANALYSES & RESULTS: Compare each set of observations (bias, dark, Kspot, intflat, visflat, UV flat) with pre-SMOV data to check for changes in
instrument performance. Weekly images throughout SMOV will be
compared to identify and trend any changes.
COMMENTS: WFPC2-08 covers non-decon weeks. Standard internals during
decon weeks are executed as part of WFPC2-03.