ACTIVITY TITLE: Activation Test (FT)
ID: WFC3-01 (11454)
APPLICABLE SMOV REQUIREMENTS: 1.1.1 and 1.1.3
DESCRIPTION: This program verifies that WFC3 is in the same condition after release from the
Shuttle as during the Functional Test (FT) conducted with HST in the Shuttle’s payload bay. The inbay FT will be run with real-time CCLs, but this analog test will be implemented in stored
commanding that will be generated from a Phase II proposal. The purpose of the FT is to demonstrate
that WFC3 is viable for scientific research. This is accomplished by demonstrating that WFC3 can be
commanded to the nominal scientific operating state and to carry out nominal scientific operations of
the UVIS and IR channels, including operation of the thermoelectric coolers (TECs), mechanisms,
filter wheels, detectors, and Control Section (CS). Only one Side of the CS is verified.
In the in-bay FT, six UVIS images are obtained, and 4 IR images. The UVIS images are: 1 full-frame
bias, 1 full-frame 20-sec dark, 2 engineering read noise tests of the 4 detector amplifiers, and 2 fullframe F606W tungsten lamp. The IR images are: 1 7-sample full-frame RAPID dark, 1 7-sample fullframe STEP25 dark, and 2 7-sample full-frame engineering read noise tests. All these images will be
obtained in this program. An additional IR exposure is required in this program in order to
demonstrate movement of the Filter Select Mechanism (FSM). That exposure will be a 7-sample fullframe RAPID F140W tungsten lamp exposure
IMPLEMENTATION METHOD: Standard Phase II proposal and commanding.
DEPENDENCIES: This proposal should be run 14-18 days into the Protect SAFE.
DURATION: Two internal orbits. No external targets are required.
DATA REQUIREMENTS: The data volume is approximately 300 MB.
ANALYSES & EXPECTED RESULTS: Ten images will be compared with the analogs from the
in-bay FT to verify that the success criteria previously obtained are still met. Telemetry will be
examined in order to verify correct operation of mechanisms, as demonstrated in the in-bay FT.
COMMENTS: Any capabilities not verified by the in-bay FT will not be attempted in execution of
this program. In that contingency, the SMS will re-generated with the affected exposures removed.
AUTHOR/telephone/email: L. Petro / 410-338-4501 / petro@stsci.edu
DATE: Jan. 30, 2008
ACTIVITY TITLE: Load and Dump On-board Memory
ID: WFC3-02 (11357)
APPLICABLE SMOV REQUIREMENTS: 1.1.4
DESCRIPTION: This program verifies the integrity of the WFC3 Control Section (CS) memory
(EXEC RAM, CS EEPROM, and CS PROM). This program is derived from the SMOV 3b ACS
program SMOV3B-ACS-02 (Proposal 9002) and from WFC3 SMGT Part 2 (Proposal 873). Only one
Side of the CS is verified.
IMPLEMENTATION METHOD: Standard Phase II proposal and special commanding.
DEPENDENCIES: This proposal should be run after release from the Shuttle and can be run during
the 21-day contamination/Protect SAFE interval.
DURATION: One internal orbit. No external targets are required.
DATA REQUIREMENTS: No science data are obtained.
ANALYSES & EXPECTED RESULTS: The memory dump will be examined in order to verify
correct contents.
COMMENTS: None.
AUTHOR/telephone/email: L. Petro / 410-338-4501 / petro@stsci.edu and I. Dashevsky / 410-3382616 / idash@stsci.edu .
DATE: Jan. 30, 2008
ACTIVITY TITLE: Science Data Buffer Check
ID: WFC3-03 (11358)
APPLICABLE SMOV REQUIREMENTS: 1.1.5
DESCRIPTION: This program verifies the integrity of the WFC3 Control Section (CS) science data
buffer memory. This program is derived from the SMOV 3b ACS program SMOV3B-ACS-03
(Proposal 9003) and from WFC3 SMGT Part 2 (Proposal 873). Only one Side of the CS is verified.
IMPLEMENTATION METHOD: Standard Phase II proposal and special commanding.
DEPENDENCIES: This proposal should be run after release from the Shuttle and can be run during
the 21-day contamination/Protect SAFE interval.
DURATION: One internal orbit. No external targets are required.
DATA REQUIREMENTS: No science data are obtained.
ANALYSES & EXPECTED RESULTS: The memory dump will be examined in order to verify
correct contents.
COMMENTS: None.
AUTHOR/telephone/email: L. Petro / 410-338-4501 / petro@stsci.edu and I. Dashevsky / 410-3382616 / idash@stsci.edu .
DATE: Jan. 30, 2008
ACTIVITY TITLE: UVIS CCD Activation
ID: WFC3-04 (11455)
APPLICABLE SMOV REQUIREMENTS: L.10.4.1.1.10
DESCRIPTION: Cool UVIS CCD detector to -83C operating setpoint. Verify detector temperature
is stable over a range of S/C thermal conditions by correlation with WFC3 thermal model.
IMPLEMENTATION METHOD: Stored command/SMS. Initial cooldown (~2 hours) should be
phased to provide telemetry visibility and forward links for real-time commanding to abort cooldown
if necessary.
DEPENDENCIES: Following 21 day detector venting period per CARD Restriction 3.4.13.16 for
the optical bench temperature and CARD Restriction 3.4.13.17 for detector enclosure window and goahead from WFC3 IPT.
DURATION: 24 hours.
DATA REQUIREMENTS: Normal WFC3 telemetry in Operate mode.
ANALYSES & EXPECTED RESULTS: Correlation with thermal model as validated by thermal
vacuum testing. Demonstrate sufficient margin to operate at all allowed S/C attitudes for science
operations over 5 year period following HST SM4.
COMMENTS: Requires replan if WFC3 unable to sustain desired operating temperature.
Contingency decision to either increase setpoint or proceed as is. Expectation from ground test is
adequate margin so failing this test implies error in thermal model or change in WFC3 performance
since ground testing.
AUTHOR/telephone/email: John MacKenty/ 410-338-4550/mackenty@stsci.edu
DATE: 1 February 2008
ACTIVITY TITLE: IR Detector Activation
ID: WFC3-05 (11456)
APPLICABLE SMOV REQUIREMENTS: L.10.4.1.1.10
DESCRIPTION: Cool IR detector to -128C operating setpoint. Verify detector temperature is stable
over a range of S/C thermal conditions by correlation with WFC3 thermal model.
IMPLEMENTATION METHOD: Stored command/SMS. Initial cooldown (~3 hours) should be
phased to provide telemetry visibility and forward links for real-time commanding to abort cooldown
if necessary.
DEPENDENCIES: Following 21 day detector venting period per CARD 3.4.13.16 for optical bench
temperature and CARD Restriction 3.4.13.17 for detector enclosure window and go-ahead from
WFC3 IPT.
DURATION: 4 days
DATA REQUIREMENTS: Normal WFC3 telemetry in Operate mode.
ANALYSES & EXPECTED RESULTS: Correlation with thermal model as validated by thermal
vacuum testing. Demonstrate sufficient margin to operate at all allowed S/C attitudes for science
operations over 5 year period following HST SM4.
COMMENTS: Requires replan if WFC3 unable to sustain desired operating temperature.
Contingency decision to either increase setpoint or proceed as is. Expectation from ground test is
adequate margin so failing this test implies error in thermal model or change in WFC3 performance
since ground testing.
AUTHOR/telephone/email: John MacKenty/ 410-338-4550/mackenty@stsci.edu
DATE: 1 February 2008
ACTIVITY TITLE: UVIS Detector Functional Test
ID: WFC3-06 (11419)
APPLICABLE SMOV REQUIREMENTS: 1.1.8
DESCRIPTION: This program measures the baseline performance and operability of CCDs using
internal observations: bias frames, darks, and internal (WFC3 calsystem) flatfields. The images will be
used to evaluate readnoise, dark current, and gain. Both chips and all four amplifiers/quadrants will be
checked; while most data will be taken in default readout mode (unbinned, four-amp gain 1.5 setting),
a small number of biases and darks will also be taken in full-frame binned modes and a set of
subarrays. A set of internal flatfields will be acquired to provide an absolute gain measurement at the
nominal setting (1.5 e-/DN) as well as a relative check at the off-nominal settings.
The majority of data from this proposal are intended as a baseline only; other proposals will obtain
additional internals (e.g., WF18, WF33) for monitoring purposes. An efficiently packed orbit begins
with 2 short exposures followed by one longer exposure, which hides the readout of the first two
images within the exposure time of the third. This proposal executes four such orbits for biases and
darks in full-frame unbinned mode (to check repeatability) as well as two orbits each for full-frame
2x2 and 3x3 binned modes, and two orbits of subarrays. The absolute gain check requires a minimum
of six pairs of flatfields in the same filter taken at a full range of exposure levels, low to high; the
relative gain is assessed with a single pair of well-exposed flatfields at each of the three off-nominal
gain settings. Flatfield performance at different wavelengths will be checked in other programs (e.g.,
WF19, WF39).
IMPLEMENTATION METHOD: Standard Phase II proposal and commanding.
DEPENDENCIES: This proposal should be run after successful completion of WF04, CCD
activation, and WF09, SOFA and Tungsten lamp test. Internal flats in this proposal would ideally
follow one of the orbits containing bias/dark frames.
DURATION:
10 internal orbits for biases/darks
4 internal orbits for internal flatfields.
No external targets are required.
DATA REQUIREMENTS:
biases/darks 521.7 Mbytes
intflats 597.6
ANALYSES & EXPECTED RESULTS: Readnoise will be measured from the overscan regions of
individual bias frames as well as from science pixel areas within difference images of pairs of biases.
Biases will be used in conjunction with biases from other programs (e.g., WF33) to generate a
superbias and confirm the locations of permanent defects such as blocked columns or dead pixels.
Dark current levels, average rates as well as hot pixel levels, will be determined from the dark frames.
Darks will be used in conjunction with darks from other programs (e.g., WF33) to generate a
superdark, monitor hot pixel behavior, and maintain hot pixel lists. An absolute gain measurement of
the default gain setting will be performed on the set of flatfield pairs; a relative gain calibration for the
off-nominal gain settings for each quadrant will be derived by comparing signal levels within flat field
images at the four different gain settings.
COMMENTS:
AUTHOR/telephone/email: S. Baggett / 410-338-5054 / sbaggett@stsci.edu
DATE: Dec 14, 2007
ACTIVITY TITLE: IR Detector Functional Test
ID: WFC3-07 (11420)
APPLICABLE SMOV REQUIREMENTS: L.10.4.1.1.9
DESCRIPTION: This program measures the baseline performance and operability of the IR
detector using only internal observations: darks and internal (WFC3 calsystem) flatfields. The images
will be used to evaluate readnoise, dark current, gain, and cursory characterization of the reference
pixels. Most data will be taken in default full-frame readout mode (four-amp, gain 2.5 setting), but in
addition darks and flats will be taken in each of the 4 subarrays. A set of internal flat fields will be
acquired to provide absolute gain measurements for each amplifier at the nominal setting (2.5 e-/DN).
The majority of data from this proposal are intended as a baseline only; other proposals will obtain
additional internals (e.g., WF20, WF34) for monitoring purposes. This proposal executes 5 internal
orbits for darks in full-frame mode and in all 4 subarrays; for expediency, the subarray exposures will
not be long enough to verify dark current is the same for them as for full-frame mode – subarrays will
verify only correct location of active and reference pixels, readnoise, and gain). Verification of system
gain requires flatfields observed multiple times with the same sample sequence in the same filter taken
at a full range of exposure levels, low to high. Flat field performance at different wavelengths will be
checked in other programs (e.g., WF20, WF40).
IMPLEMENTATION METHOD: Standard Phase II proposal and commanding.
DEPENDENCIES: This proposal should be run after successful completion of WF05, IR detector
activation, and after WF10, IR FSM and Tungsten lamp test. Flats with the shortest-exposures would
ideally follow soon after dark frames to optimize dark-subtraction from those flats in particular.
DURATION:
5 internal orbits for darks
1 internal orbits for internal flatfields.
DATA REQUIREMENTS:
706 Mbytes (tally is in notes at end of document)
ANALYSES & EXPECTED RESULTS: Readnoise and dark current will be measured from
differences of short exposures (readnoise) and long exposures (dark current). Dark current levels,
average rates as well as hot and warm pixel levels, will be determined from the dark frames;
anticipated dark current is 0.02 e/sec/pixel (Table 7.12 Handbook). SPARS200 observations can be
interpolated to synthesize darks for all other sample sequences without extrapolation. The gain will be
verified from the flats using the photon transfer technique. The structure of the flats will be compared
to those obtained during ground tests to note any changes. Data from this program will supplement
data from other programs (e.g., WF20,WF34,WF40) but the analysis of this program will be more
prompt and more preliminary than those later programs. Results from subarray observations will be
compared to the associated full-frame regions of the sensor to note differences if any.
COMMENTS:
AUTHOR/telephone/email: P. McCullough / 410-338-5068 / pmcc@stsci.edu
DATE: Jan 10, 2008
NOTES:
From WF20, we learn that of WFC3 filters, F110W has the greatest irradiance for flats and thus the
minimum time to accumulate 30kADU/pixel (14.6 sec) with a RAPID NSAMP=5. We may want a
lower-irradiance flat for comparison in case this sensor has reciprocity failure (due to detector physics
or due to backend miscalibration of exposure time etc).
Execute this:
10 repeats of [ short (RAPID NSAMP=5; 15 sec) and long exposure darks (SPARS200 gives 2803
sec) ] = 10*((15+20)+(2803+20)) = 28580 sec = 5 orbits; 10*(5+1+15+1) = 220 frames; 2 MB each.
10 repeats of subarray darks (short exposures as before – we expect little demand for dark current
measurement in subarrays): 10*4 subarrays * (15+20 sec) = 1400 sec; 10*4*(5+1) = 240 subarray
frames; 10*(2/3 MB)*(5+1) = 40 MB
10 repeats of various exposure (use NSAMP=5) subarray flats for photon transfer (high irradiance =
F110W) = 10*4 subarrays * (15+20 sec) = 1400 sec ; 240 frames and 40 MB again;
10 repeats of various exposure (use NSAMP=5) flats for photon transfer (high irradiance = F110W):
10*(15+20 sec) = 350 sec; 10*(5+1) = 60 frames; 2 MB each.
3 repeats of low-irradiance flat (any N filter, say F126N) with SPARS50 NSAMP=10 gives 30x lower
irradiance than F110W and requires 452 sec each: 3*(452+20 sec)=1416 sec; 3*(10+1) = 33 frames; 2
MB each.
Total of above = 33146 sec = 552 min = 6 orbits ignoring commanding etc overheads (it does include
20 sec readout overhead). Total = 706 MB.
ACTIVITY TITLE: Channel Select Mechanism Test
ID: WFC3-08 (11421)
APPLICABLE SMOV REQUIREMENTS: 1.1.6
DESCRIPTION: The purpose of this test is to verify the proper positioning of the Channel Select
Mechanism (CSM) for both UVIS and IR channel observations, such that the UVIS beam is not
obstructed by the CSM when it is retracted from the incoming light path and the IR field is completely
filled by the CSM mirror when in the IR position. An ancillary purpose is to verify that the IR diffuser
paddle is properly positioned for obtaining internal IR flats when the CSM is in the UVIS position.
Full-frame exposures of a target such as NGC 188, which will fill the field of view, will be obtained
with the CSM in each of the UVIS and IR channel positions. A target that fills the field of view will
allow us to verify that the entire field of each channel is properly filled, with no part of the field
obstructed or otherwise invisible due to CSM positioning errors.
Proper positioning of the IR diffuser paddle will be verified using internal IR flat field exposures. The
size of the internal calibration source beam as it fills the diffuser paddle is wavelength-dependent,
resulting in different levels of signal roll-off in the corners of the field for different IR filters. Two IR
internal flats will therefore be obtained, one each in a short- and long-wavelength IR filter, such as the
F098M and the F160W.
IMPLEMENTATION METHOD: Stored commanding.
DEPENDENCIES: WFC3-04, WFC3-05
DURATION: 2 external and 1 internal orbits
DATA REQUIREMENTS: 650 Mbits
ANALYSES & EXPECTED RESULTS: External images for each channel will be visually
inspected to verify that the entire field of view contains sky signal and is not in anyway obstructed or
rendered invisible due to CSM positioning errors. IR internal flats will be inspected to verify that the
position of the IR diffuser paddle provides minimal roll-off of signal levels in the corners of the IR
flats and is similar to the signal gradients seen in ground-based flats for the same filters.
COMMENTS:
AUTHOR/telephone/email: Howard Bushouse/410-338-4530/bushouse@stsci.edu
DATE: December 20, 2007
ACTIVITY TITLE: SOFA and Tungsten Lamp
ID: WFC3-09 (11422)
APPLICABLE SMOV REQUIREMENTS: 1.1.6, 1.1.7
DESCRIPTION: This proposal will verify the operation of all SOFA filter wheels as well as that of
the calsystem tungsten lamps. Internal flat fields will be obtained in one filter from each of the twelve
filter wheels, establishing an initial baseline over a broad wavelength range. Subsequent proposals
(e.g., WF19) will obtain full flat field coverage in all UVIS filters. Filters for this proposal were
chosen based upon a balance of multiple factors: reasonable count rate with calsystem tungsten lamp
(no long exposure times), science priority of the filter, overall coverage of UVIS wavelength regime,
and slot location in the wheel. Exposures will be taken in the default full-frame, four-amp, unbinned
readout mode.
A flat field using one filter per wheel will be obtained with each of the two tungsten lamps nominally
assigned to the UVIS channel, verifying both wheel and lamp operability and allowing for a lamp flux
cross-check. In addition, two flatfields in each of the other two tungsten lamps will be acquired,
providing a verification of the bulb health and a spot-check of flux levels (these two lamps are
nominally designated for use with the IR channel but any of the four bulbs can be used with either
channel if necessary).
wheel filter
1 F656N 4
2 F200LP 3
3 F657N 3
4 F645N 4
5 F625W 1
6 F606W 2
7 F555W 1
8 F763M 4
9 F467M 3
10
F475X
11
F350LP
12
FQ889N
slot
3
2
3
IMPLEMENTATION METHOD: Standard Phase II proposal and commanding.
DEPENDENCIES: Should be run after WFC3-08, CSM Test, but before WF06, CCD functional
test, to confirm lamp operations before gain images are obtained in WF06.
DURATION:
7 internal orbits (3 needed for internals for each of the 2 primary lamps plus 1 orbit for the cross-check
of the other two lamps).
No external targets are required.
DATA REQUIREMENTS:
929.6 Mbytes
ANALYSES & EXPECTED RESULTS: Flatfield illumination patterns will be analyzed and
compared to previous ground test results to check for any changes in filter structures, vignetting within
field, etc. Flux levels of the tungsten lamps will be compared to previous ground test results to verify
performance of the bulbs. Data will be used, along with internal flats from other proposals, to generate
on-orbit updates for the calibration pipeline flatfield reference files.
COMMENTS:
AUTHOR/telephone/email: S. Baggett / 410-338-5054 / sbaggett@stsci.edu
DATE: Dec 14, 2007
ACTIVITY TITLE: IR FSM and Tungsten Lamp Test
ID: WFC3-10 (11423)
APPLICABLE SMOV REQUIREMENTS: 1.1.6, 1.1.7
DESCRIPTION: This proposal will verify the operation of the IR filter wheel (FSM) as well as that
of the calsystem tungsten lamps. A baseline will be established by obtaining one internal flatfield in
each IR filter using each of the two nominal IR channel lamps, plus one dark in each of the different
sample sequence types used (estimated at 3). In addition, two flatfields for each of the other two bulbs
will be taken to provide a verification of the bulb health and a spot-check of the bulb flux (these two
lamps are nominally designated for use with the UVIS channel but any of the four bulbs can be used
with either channel ). A separate proposal (WF20) will obtain additional flatfields in each filter for
CDBS reference file generation.
IMPLEMENTATION METHOD: Standard Phase II proposal and commanding.
DEPENDENCIES: Should be run after WFC3-08, CSM Test, but before WFC3-07 (IR functional).
DURATION: 14 orbits (6 with each IR channel lamp plus 2 additional orbits for spot-check of the
other two lamps). No external targets are required.
DATA REQUIREMENTS:
1408 Mbytes (this is an upper limit to the data volume, as it assumes nsamp=15 for all filters though
some filters will not need all 15)
ANALYSES & EXPECTED RESULTS:
Flatfield illumination patterns will be analyzed and compared to previous ground test results to check
for any changes in filter structures, vignetting within field, etc. Flux levels of the tungsten lamps will
be compared to previous ground test results to verify performance of the bulbs. Data will be used,
along with internal flats from other proposals, to generate updates for calibration pipeline flatfield
reference files.
COMMENTS:
AUTHOR/telephone/email: S. Baggett / 410-338-5054 / sbaggett@stsci.edu
DATE: Jan 2,2008
ACTIVITY TITLE: Initial UVIS Alignment
ID: WFC3-11 (11424)
APPLICABLE SMOV REQUIREMENTS: 1.2.1, 1.2.2
DESCRIPTION: The UVIS corrector mechanism will be used to bring the instrument into
alignment with the OTA using phase retrieval (PR) of focus diverse star images over the field.
Corrector tip/tilt (inner/outer cylinders) will be adjusted to align the OTA and UVIS pupils, and the
focus drive will be used to obtain the PR images and optimize image focus. The observed field must
be sufficiently dense to provide good sampling over the FOV while providing enough isolated stars to
permit accurate PSF measurement. If the field is astrometric and astrometric guide stars are used, the
plate scale and image orientation may also be determined. NGC-188 star 58 is a likely target, available
year-round and used previously for ACS alignment. The F410M filter will be used to limit the
passband at relatively short wavelength for improved PR accuracy. Full frame CR-split images will be
obtained at 5 focus positions. Three visits are required; corrector offsets will be uplinked after each
visit via realtime command, no sooner than 24 hrs after receipt of full data set.
IMPLEMENTATION METHOD: SMS
DEPENDENCIES: This must occur after internal instrument checkout and prior to any other
external target observations other than WFC3-08 (CSM Test).
DURATION: 6 orbits
DATA REQUIREMENTS: 12 full frame UVIS images (~400 MB) will be generated per visit.
ANALYSES & EXPECTED RESULTS: PR analyses will be performed to determine the amount of
coma present, which will be used to compute the required corrector cylinder offsets. Focus will be
similarly adjusted to optimize performance over the field.
COMMENTS:
AUTHOR/telephone/email: George Hartig/x4966/hartig@stsci.edu
DATE: 25 Jan 2008
ACTIVITY TITLE: Initial IR Alignment
ID: WFC3-12 (11425)
APPLICABLE SMOV REQUIREMENTS: 1.2.1, 1.2.2
DESCRIPTION: The IR corrector mechanism will be used to bring the instrument into alignment
with the OTA using phase retrieval (PR) of focus diverse star images over the field. Corrector tip/tilt
(inner/outer cylinders) will be adjusted to align the OTA and IR pupils, and the focus drive will be
used to obtain the PR images and optimize image focus. The observed field must be sufficiently dense
to provide good sampling over the FOV while providing enough isolated stars to permit accurate PSF
measurement. If the field is astrometric and astrometric guide stars are used, the plate scale and image
orientation may also be determined. NGC-188 star 58 is a likely target, available year-round and used
previously for ACS alignment. The F098M filter will be used to limit the passband at relatively short
wavelength for improved PR accuracy. Full frame, 16 read images will be obtained at 5 focus
positions. Three visits are required; corrector offsets will be uplinked after each visit via realtime
command, no sooner than 24 hrs after receipt of full data set.
IMPLEMENTATION METHOD: SMS
DEPENDENCIES: This must occur after internal instrument checkout and prior to any other
external target observations other than WFC-08 (CSM Test).
DURATION: 6 orbits
DATA REQUIREMENTS: 6 full frame, 16 read, RAPID IR images (~200 MB) will be generated
per visit.
ANALYSES & EXPECTED RESULTS: PR analyses will be performed to determine the amount of
coma present, which will be used to compute the required corrector cylinder offsets. Focus will be
similarly adjusted to optimize performance over the field.
COMMENTS:
AUTHOR/telephone/email: George Hartig/x4966/hartig@stsci.edu
DATE: 25 Jan 2008
ACTIVITY TITLE: UVIS SMOV Contamination Monitor
ID: WFC3-13 (11426)
APPLICABLE SMOV REQUIREMENTS: 1.1.12, 1.3.6
DESCRIPTION: This proposal will monitor the UV throughput of WFC3 during SMOV via
standard star observations in a subset of key filters (as many as will fit into a single orbit but to include
at a minimum F218W, F225W, F275W, and F606W). The set of observations will be obtained via one
full-frame image to insure the star falls in the field-of-view followed by subarrays positioned at two
locations in the WFC3 field-of-view (one position per chip). The full frame will be acquired in the first
visit only as a refinement tool. The data will provide a measure of throughput levels as a function of
time and wavelength, allowing for detection of the presence of possible contaminants. Concurrent
with the standard star imaging, full-frame, four-amp readout internal exposures will taken to serve as a
stability monitor; these will consist of 2 biases, 2 darks, and three internal flat fields (F336W, F438W,
F606W). Due to the limited lifetime of the deuterium lamp, the internal flat fields here are restricted to
the tungsten bulbs. Should D2 lamp flat fields be necessary to supplement data from this proposal,
they are obtained via two other programs: WF15, the D2 lamp test (several iterations of a relatively
large set of UV flat fields for monitoring purposes) and WF19, internal flat fields (multiple flat fields
in all UV filters, for reference file generation).
IMPLEMENTATION METHOD: Standard Phase II proposal and commanding.
DEPENDENCIES: Can not be run until after successful completion of WF06 (UVIS functional).
DURATION: First visit should be during the first week after the end of the 21 day venting period
i.e. between days 21 and 28. Subsequent visits are weekly.
Assuming SMOV length of 5 weeks:
10 external orbits total (2 orbits once per week: 1 orbit per chip)
10 internal orbits (2 per week)
DATA REQUIREMENTS:
Estimate ~1295 Mbytes total (259 per iteration, assuming that each iteration will contain 28 512x512
subarray images/orbit, at 2 locations, plus 7 full-frame images)
ANALYSES & EXPECTED RESULTS:
Standard star data from the UV throughput monitor will be reduced using aperture photometry; results
will be tracked as a function of time and wavelength to search for any sign of contamination effects.
Internals will be evaluated for any changes in readnoise, dark current, or flatfield structure.
COMMENTS:
AUTHOR/telephone/email: S. Baggett / 410-338-5054 / sbaggett@stsci.edu
DATE: Jan 3,2008
ACTIVITY TITLE: UVIS Shutter Test
ID: WFC3-14 (11427)
APPLICABLE SMOV REQUIREMENTS: 1.1.6
DESCRIPTION:
This test will provide calibration data to characterize the performance of the WFC3 UVIS shutter.
Images with exposure times ranging from 0.5 to 25 seconds will be used to quantify shutter shading,
accuracy, and stability.
IMPLEMENTATION METHOD: Stored Commanding
DEPENDENCIES: WFC3-11 – UVIS Initial Alignment
DURATION: 1 internal + 2 external orbits
DATA REQUIREMENTS:
This activity will produce 6 full-frame UVIS images (during the internal orbit) and 70 512x512
subarray images (during the external orbits). This corresponds to 192MB from the full-frame images
and 35 MB from the subarrays, for a total of 227 MB (1816 Mbits).
ANALYSES & EXPECTED RESULTS:
Using internal flat field data taken with the Tungsten lamp and F555W filter, we will search for any
shutter shading effects in the UVIS channel. Any large shading effects will prompt a calibration to be
added to CALWF3.
We will also quantify the accuracy and repeatability of the UVIS shutter through photometry of
standard star observations. We propose subarray observations of the standard star Grw+70 5824
through the F395N filter for a range of exposure times for this purpose. Similar tests have been
performed in Thermal Vacuum testing. In those tests, no appreciable shutter shading was found, and
the shutter was found to be repeatable to the 1% level except for commanded exposure times of 0.7
and 0.8 seconds.
AUTHOR/telephone/email:
Bryan Hilbert
410-338-4725
Hilbert@stsci.edu
DATE:
12/20/2007
NOTES:
Current plan:
Internal:
F555W in TV2 had a countrate with the tungsten lamp, of ~2389 e-/sec/pixel
so 0.5 sec = 1195 e1.0 sec = 2390 e30 sec = 71700 e- -- too high?
Maybe try 25 sec instead, for ~60ke-? – but these numbers are for UVIS2…
To switch from UVIS2 to UVIS1 : countrate on UVIS1 = countrate on UVIS2*1.0101 (for the
F555W filter)
So for UVIS1, Tungsten lamp countrate through f555w will be ~2440 e-/pix/sec
0.5 sec – 1220e1.0 sec – 2440e25 sec – 61,000eExternal:
2 points on the detector (upper right and lower left corners, corresponding to beginning and ending of
shutter sweep across the detector)
For each point, take 512x512 images of Grw +70 5824 through F395N:
Exp time (sec)
0.5
0.7
0.8
1.0
30
# imgs
9
9
9
4
4
ACTIVITY TITLE: D2 Calibration lamp test
ID: WFC3-15 (11428)
APPLICABLE SMOV REQUIREMENTS: 1.1.7
DESCRIPTION: This proposal verifies the health and performance of the calsystem deuterium lamp
and assesses the status of the major UV filters by taking a full set of internal flatfields, one image per
filter. The program is run a total of three times, in order to establish an initial baseline of flatfield data
as well as to confirm lamp repeatability and provide a contamination check. Additional iterations of
D2 internal flatfields will be taken as part of WF19 (UVIS Internal Flats).
IMPLEMENTATION METHOD: Standard Phase II proposal and commanding.
DEPENDENCIES: Can not be run until after successful completion of WF06 and WF11, the CCD
functional test and initial alignment activities, respectively. Approval from R. Kimble and/or J.
MacKenty is required before proceeding with this program because of possible contamination issues.
DURATION: 9 internal orbits (3 orbits, run 3 times); no external orbits required.
DATA REQUIREMENTS: 1394.4 Mbytes (464.8 per run)
ANALYSES & EXPECTED RESULTS
Flux levels within the flat fields will be compared to those from ground data to evaluate the D2 lamp
performance. Flat field illumination patterns will be analyzed for any changes compared to previous
ground test images. The three runs of the proposal will provide a preliminary check of the lamp’s
firing behavior on-orbit (occasional delays in the lamp turn-on have been experienced in recent ground
tests) while the repeated flatfields will provide a check of the lamp output stability as well as a monitor
for possible time-dependent changes due to e.g., contamination . The data will be combined with that
from WF19 to generate on-orbit updates for the WFC3 calibration pipeline flatfield reference files.
COMMENTS:
AUTHOR/telephone/email: S. Baggett / 410-338-5054 / sbaggett@stsci.edu
DATE: Dec 20, 2007
ACTIVITY TITLE: UVIS TEC Performance
ID: WFC3-16 (11429)
APPLICABLE SMOV REQUIREMENTS: 1.1.10
DESCRIPTION: This program verifies that the performance of the WFC3 UVIS 4stage TEC is
adequate to maintain the detector at the science setpoint under worstcase thermal conditions. The
detector’s temperature setpoint for science operations will be determined during the Thermal Vacuum
(T/V) ground test (expected to be approximately -89˚ C). The ability of the TEC to maintain that
detector setpoint temperature is demonstrated in T/V by simulating the worst case on orbit thermal
environment, as predicted by GSFC’s thermal models. The thermal environment is a function of the
spacecraft aspect (angles between the Sun and the orbit pole, HST line of sight, and solar array
normal; and off-nominal roll), thermal flux (solar, reflected Earth, and Earth thermal), and orbit
altitude.
In this program, telemetry of the TEC’s thermal performance during routine SMOV observations will
be gathered. The GSFC thermal model will be used to forecast the increase of power necessary to
maintain the temperature setpoint under worstcase thermal conditions, using the SMOV onorbit
telemetry to provide an empirical zeropoint for the GSFC model.
IMPLEMENTATION METHOD: None.
DEPENDENCIES: This proposal should be run after completion of WFC3-04 (UVIS CCD
Activation).
DURATION: 1 week
DATA REQUIREMENTS: Normal telemetry.
ANALYSES & EXPECTED RESULTS: The telemetry of TEC power and detector temperature
will be analyzed as a function of spacecraft thermal environment and compared with the predictions of
the GSFC thermal model for the same environment. The GSFC model will be used to predict the
increase of power necessary in order to maintain the detector temperature under worstcase thermal
operating conditions and environment.
COMMENTS: None.
AUTHOR/telephone/email: L. Petro / 410-338-4501 / petro@stsci.edu and T. Wheeler / 410-3384337 / wheeler@stsci.edu .
DATE: Jan. 31, 2008
ACTIVITY TITLE: IR TEC Performance
ID: WFC3-17 (11430)
APPLICABLE SMOV REQUIREMENTS: 1.1.10
DESCRIPTION: This program verifies that the performance of the WFC3 IR thermoelectric coolers
(TECs) are adequate to maintain the detector at the science set-point under worst-case thermal
conditions. The detector’s temperature set-point for science operations will be determined during the
Thermal Vacuum (T/V) ground test (expected to be approximately -128˚ C (145 K)). The ability of the
TECFIRE and 6-stage TECs to maintain that detector set-point temperature is demonstrated in T/V by
simulating the worst-case on-orbit thermal environment, as predicted by GSFC’s thermal models. The
thermal environment is a function of the spacecraft aspect (angles between the Sun and the orbit pole,
HST line of sight, and solar array normal; and off-nominal roll), thermal flux (solar, reflected Earth,
and Earth thermal), and orbit altitude.
In this program, telemetry of the TECs’ thermal performance during routine SMOV observations will
be gathered. The GSFC thermal model will be used to forecast the increase of power necessary to
maintain the temperature set-point under worst-case thermal conditions, using the SMOV on-orbit
telemetry to provide an empirical zero-point for the GSFC model.
IMPLEMENTATION METHOD: None.
DEPENDENCIES: This proposal should be run after completion WFC3-12, “IR Initial Alignment.”
DURATION: 2 weeks
DATA REQUIREMENTS: Normal telemetry.
ANALYSES & EXPECTED RESULTS: The telemetry of TEC power and detector temperature
will be analyzed as a function of spacecraft thermal environment and compared with the predictions of
the GSFC thermal model for the same environment. The GSFC model will be used to predict the
increase of power necessary in order to maintain the detector temperature under worst-case thermal
operating conditions and environment.
COMMENTS: None.
AUTHOR/telephone/email: L. Petro / 410-338-4501 / petro@stsci.edu and T. Wheeler / 410-3384337 / wheeler@stsci.edu .
DATE: Jan. 31, 2008
ACTIVITY TITLE: UVIS Hot Pixel Anneal
ID: WFC3-18 (11431)
APPLICABLE SMOV REQUIREMENTS: 1.1.11
DESCRIPTION: The intent of this proposal is to demonstrate the ability to perform a UVIS anneal
within 30 days of the initial cooldown of the UVIS detector. During this procedure, the thermo-electric
coolers are turned off and the heaters turned on, bringing the CCDs up to ~20C. Full-frame, unbinned
bias and dark frames (3 and 5, respectively) are obtained immediately prior to and following the
anneal, to allow assessment of the effectiveness of the anneal. After two successful iterations of this
proposal, subsequent anneal procedures will be performed via the cycle 17 UVIS anneal proposal.
IMPLEMENTATION METHOD: Standard Phase II proposal and commanding.
DEPENDENCIES: Can not be run until after successful completion of WF06, CCD functional test.
Also, WF16 (UVIS TEC performance) must be executed before as well.
DURATION:
Total of 16 internal orbits (8 per anneal procedure: 4 orbits before, 4 after)
Additional time required: anneal is currently set at ~13.8 hrs (12 for anneal itself, 1.8 for setup) plus
cooling time (estimate about 3 hrs)
DATA REQUIREMENTS: 1062.4 Mbytes (531.2 per anneal: 16 full-frame images)
ANALYSES & EXPECTED RESULTS
Bias and darks will be compared to baseline images, hot pixel changes will be monitored, and the
effectiveness of the anneal procedure will be evaluated. Data will also be combined with that from
other proposals to generate superbias and superdark reference files for the calibration pipeline.
COMMENTS: Execute this program about 30 +/- 3 days after WFC3-04 (UVIS CCD Activation)
AUTHOR/telephone/email: S. Baggett / 410-338-5054 / sbaggett@stsci.edu
DATE: Dec 19, 2007
ACTIVITY TITLE: UVIS Internal Flats
ID: WFC3-19 (11432)
APPLICABLE SMOV REQUIREMENTS: 1.3.7, 1.1.6, 1.1.7
DESCRIPTION: Observations will be used to assess the stability of the flat field structure for the
UVIS detector. Flat fields will be obtained for all filters using the internal D2 and Tungsten lamps.
There are 42 full filters and 5 “quad” filters (each with 4 narrow bandpass filters; grism will be
addressed in Cycle 17). Of the 42 filters, 18 are science priority 1 filters, 19 are science priority 2, and
5 are science priority 3. The quad filters are also science priority 3. Science priority 1 filters need 6
flats per filter. For the other 24 science priority 2 and 3 filters and 20 quad-filters, 4 flats per filter will
be obtained.
18 priority-1 filters * 6 exp = 108 exp * 1 orb / 3 exp = 36 orbits
19 priority-2 filters * 4 exp = 76 exp * 1 orb / 3 exp = 26 orbits
5 priority-3 filters * 4 exp = 20 exp * 1 orb / 3 exp = 7 orbits
Cross-check between D2/Tungsten = 2 filters * 4 exp = 8 exp * 1 orb / 3 exp = 3 orbits
Extra exposures for ERO filters (assume 2 priority-1 and 2 priority-2 filters) = 7 orbits
2 priority-1 filters = 2 * 4 exp = 8 exp * 1 orb / 3 exp = 3 orbits
2 priority-2 filters = 2 * 6 exp = 12 exp * 1 orb / 3 exp = 4 orbits
20 quad priority-3 filters * 4 exp = 80 exp * 1 orb / 3 exp = 27 orbits
IMPLEMENTATION METHOD: Stored commanding.
DEPENDENCIES: Same as WFC3-11, UVIS Initial Alignment.
DURATION: Estimated total of orbits: 36+26+7+3+7+27 = 106 internal orbits
Priority-1 filters
= 36 orbits
Priority-2 filters
= 26 orbits
Priority-3 filters
= 7 orbits
Cross-check lamps
= 3 orbits
4 ERO filters
= 7 orbits
20 quad priority-3 filts = 27 orbits
DATA REQUIREMENTS: 312 exposures * 34 MB = 10608 MB
Total UVIS exposures needed = 312 exposures = [108 (prio. 1) + 76 (prio. 2) + 20 (prio. 3) + 8
(cross-check) + 20 (ERO) + 80 (quads)]
ANALYSES & EXPECTED RESULTS: IRAF and/or IDL software will be used to analyze the
structure of the flats. Results of this program will be used to calibrate ERO observations made during
SMOV and will also serve as a baseline for flat stability checks in the future.
COMMENTS: This is a high-priority program needed for ERO SMOV calibration.
AUTHOR/telephone/email: Jessica Kim Quijano/410-338-4786/jkim@stsci.edu
Sylvia Baggett/410-338-5054/sbaggett@stsci.edu
DATE: January 17, 2008.
ACTIVITY TITLE:
IR Internal Flats
ID: WFC3-20 (11433)
APPLICABLE SMOV REQUIREMENTS: 1.3.7, 1.1.6, 1.1.7
DESCRIPTION:
In this test, we will study the stability of the IR channel flat field images through all filter
elements in the WFC3-IR channel. Flat field images for each filter will be combined in
order to produce a calibration-quality flat field image. High signal observations will
provide a map of the pixel-to-pixel flat field structure, as well as identify the positions of
any dust particles.
IMPLEMENTATION METHOD: Stored Commanding
DEPENDENCIES: WFC3-12 (IR Initial Alignment)
DURATION:
44 internal orbits (54 minutes per orbit). This is a conservative estimate, using relatively
inefficient packing of the observations. This is due to a ~20% uncertainty in the flux
level of the new Tungsten lamp currently being installed in WFC3.
DATA REQUIREMENTS:
This activity will produce 300 ramps (20 ramps per filter x 15 filters). Not all ramps will
contain the full 15 NSAMP. We estimate a total data volume of 6680 MB (53440 Mbits).
This is based on a data volume of 32MB per 16-read ramp. Again, the uncertainty in the
new lamp flux means that there is some uncertainty in this number, as the number of
reads per ramp may change once the true lamp flux is known.
ANALYSES & EXPECTED RESULTS:
Ramps for each filter will be combined in order to produce a flat field calibration image
for that filter. The flat field for each filter will be characterized.
AUTHOR/telephone/email:
Bryan Hilbert
410-338-4725
Hilbert@stsi.edu
DATE:
12/20/2007
NOTES:
Current plan (20 repetitions of the table below):
Filter Estimated Meas. Flux
(ADU/sec/pix)
Time to 30kADU SampSeq
(sec)
NSAMP
RAPID
11
RAPID
Data Vol
(MB)
F105W
F110W
12
F125W
18
F140W
14
F160W
980
2058
30.6
14.6
24
1367
22.0
RAPID
8
~1650
~17
RAPID
6
1309
23.0
RAPID8
F098M
F127M
F139M
F153M
407
323
289
331
74
92.8
103.8
90.5
SPARS10
SPARS10
SPARS10
SPARS10
9
10
12
10
20
22
26
22
F126N
F128N
F130N
F132N
F164N
F167N
59
66
70
~65
82
89
511.9
451.7
425.4
~455
365.7
336.9
SPARS50
SPARS50
STEP50
SPARS50
STEP50
SPARS25
11
10
14
10
13
15
24
22
30
22
28
32
5
18
ACTIVITY TITLE: UVIS Fine Alignment
ID: WFC3-21(11434)
APPLICABLE SMOV REQUIREMENTS: 1.2.1, 1.2.2
DESCRIPTION: The UVIS corrector mechanism will be used to bring the instrument
into fine alignment with the OTA using analysis of star images over the field. Two visits
are required. In the first visit, a fine scan over 7 positions of the corrector focus stage will
be used to optimize focus. This will be followed in the second visit, after optimal focus
position has been set via realtime command, by a fine tip/tilt raster (rotation of
inner/outer cylinders) to achieve fine alignment of the OTA and UVIS pupils. The
observed field must be sufficiently dense to provide good sampling over the FOV while
providing enough isolated stars to permit accurate PSF measurement. If the field is
astrometric and astrometric guide stars are used, the plate scale and image orientation
may also be determined. NGC-188 star 58 is a likely target, available year-round and
used previously for ACS alignment. The F410M filter will be used to limit the passband
at relatively short wavelength where the PSF is sharpest. Full frame CR split images will
be obtained at each corrector setting.
IMPLEMENTATION METHOD: SMS
DEPENDENCIES: This must occur after the final visit of WFC3-11, Initial UVIS
Alignment, and the resulting corrector settings have been applied as well as after WFC316 (UVIS TEC Performance).
DURATION: 7 orbits
DATA REQUIREMENTS: 18 full frame UVIS images (~600 MB) will be generated in
the first visit, and 22 (~ 700 MB) in the second.
ANALYSES & EXPECTED RESULTS: PSF analyses (encircled energy, sharpness,
FWHM, PR) will be performed to determine the corrector positions at which
performance is optimized over the field.
COMMENTS:
AUTHOR/telephone/email: George Hartig/x4966/hartig@stsci.edu
DATE: 25 Jan 2008
ACTIVITY TITLE: IR Fine Alignment
ID: WFC3-22 (11435)
APPLICABLE SMOV REQUIREMENTS: 1.2.1, 1.2.2
DESCRIPTION: The IR corrector mechanism will be used to bring the instrument into
fine alignment with the OTA using analysis of star images over the field. Two visits are
required. In the first visit, a fine scan over 7 positions of the corrector focus stage will be
used to optimize focus. This will be followed in the second visit, after optimal focus
position has been set via realtime command, by a fine tip/tilt raster (rotation of
inner/outer cylinders) to achieve fine alignment of the OTA and IR pupils. The observed
field must be sufficiently dense to provide good sampling over the FOV while providing
enough isolated stars to permit accurate PSF measurement. If the field is astrometric and
astrometric guide stars are used, the plate scale and image orientation may also be
determined. NGC-188 star 58 is a likely target, available year-round and used previously
for ACS alignment. The F098M filter will be used to limit the passband at relatively short
wavelength where the PSF is sharpest. Full frame, 16 read, dithered images will be
obtained at each corrector setting.
IMPLEMENTATION METHOD: SMS
DEPENDENCIES: This must occur after the final visit of WFC3-12, Initial IR
Alignment, and the resulting corrector settings have been applied as well as after WFC317 (IR TEC Performance).
DURATION: 7 orbits
DATA REQUIREMENTS: 18 full frame, 16 read IR images (~600 MB) will be
generated in the first visit, and 22 (~700 MB) in the second.
ANALYSES & EXPECTED RESULTS: PSF analyses (encircled energy, sharpness,
FWHM, PR) will be performed to determine the corrector positions at which
performance is optimized over the field.
COMMENTS:
AUTHOR/telephone/email: George Hartig/x4966/hartig@stsci.edu
DATE: 25 Jan 2008
ACTIVITY TITLE: UVIS Image Quality
ID: WFC3-23 (11436)
APPLICABLE SMOV REQUIREMENTS: 1.2.2
DESCRIPTION: The UVIS imaging performance over field will be assessed in two
passbands to verify PSF encircled energy CEI specifications at 250 and 633 nm, after the
instrument has been aligned to the OTA. The observed field must be sufficiently dense to
provide good sampling over the FOV while providing enough isolated stars to permit
accurate PSF measurement. If the field is astrometric and astrometric guide stars are
used, the plate scale and image orientation may also be determined. NGC-188 star 58 is a
likely target, available year-round and used previously for ACS alignment. The F275W
and F621M filters will be used. Full frame images will be obtained at each of 4 dither
positions designed to improve PSF sampling. Sampling of the field may be improved by
larger POS-TARG offsets.
IMPLEMENTATION METHOD: SMS
DEPENDENCIES: This must occur after the final visit of WFC3-21, UVIS Fine
Alignment, and the resulting corrector settings have been applied
DURATION: 2 orbits
DATA REQUIREMENTS: 12 full frame UVIS images (~400 MB) will be generated.
ANALYSES & EXPECTED RESULTS: PSF analyses (encircled energy, sharpness,
FWHM, PR) will be performed to assess imaging performance over the field.
COMMENTS:
AUTHOR/telephone/email: George Hartig/x4966/hartig@stsci.edu
DATE: 25 Jan 2008
ACTIVITY TITLE: IR Image Quality
ID: WFC3-24 (11437)
APPLICABLE SMOV REQUIREMENTS: 1.2.2
DESCRIPTION: The IR imaging performance over field will be assessed in two
passbands to verify PSF encircled energy CEI specifications at 1 and 1.6 um, after the
instrument has been aligned to the OTA. The observed field must be sufficiently dense to
provide good sampling over the FOV while providing enough isolated stars to permit
accurate PSF measurement. If the field is astrometric and astrometric guide stars are
used, the plate scale and image orientation may also be determined. NGC-188 star 58 is a
likely target, available year-round and used previously for ACS alignment. The F098M
and F164N filters will be used. Full frame, 16 read images will be obtained at each of 4
dither positions designed to improve PSF sampling. Sampling of the field may be
improved by larger POS-TARG offsets.
IMPLEMENTATION METHOD: SMS
DEPENDENCIES: This must occur after the final visit of WFC3-22, IR Fine
Alignment, and the resulting corrector settings have been applied.
DURATION: 2 orbits
DATA REQUIREMENTS: 12 full frame, 16 readout, IR images (~400 MB) will be
generated.
ANALYSES & EXPECTED RESULTS: PSF analyses (encircled energy, sharpness,
FWHM, PR) will be performed to assess imaging performance over the field.
Comparison will be made with CEI EE specs.
COMMENTS:
AUTHOR/telephone/email: George Hartig/x4966/hartig@stsci.edu
DATE: 25 Jan 2008
ACTIVITY TITLE: UVIS PSF Wings
ID: WFC3-25 (11438)
APPLICABLE SMOV REQUIREMENTS: 1.2.4
DESCRIPTION: The UVIS PSF wings will be evaluated at 5 field points, near field
center and corners in two passbands to verify CEI specifications at 250 and 633 nm. The
F275W and F621M filters will be used. Full frame images of a moderately bright,
isolated star will be obtained at each field position with a series of increasing exposure
times designed to permit construction of a very high SNR PSF with dynamic range
sufficient to evaluate the wing intensity to >5 arcsec radius. The images will also permit
examination of potential straylight effects and electronic cross-talk.
IMPLEMENTATION METHOD: SMS
DEPENDENCIES: This must occur after WFC3-23, UVIS Image Quality.
DURATION: 5 orbits
DATA REQUIREMENTS: 40 full frame UVIS images (1.36 GB) will be generated.
ANALYSES & EXPECTED RESULTS: A high dynamic range PSF will be
constructed for each of the 5 field positions and azimuthal average intensities will be
computed to compare with the CEI specs. Images will be inspected for straylight and
electronic cross-talk artifacts. Dark images following the PSF overexposure will be used
to measure image persistence.
COMMENTS:
AUTHOR/telephone/email: George Hartig/x4966/hartig@stsci.edu
DATE: 25 Jan 2008
ACTIVITY TITLE: IR PSF Wings
ID: WFC3-26 (11439)
APPLICABLE SMOV REQUIREMENTS: 1.2.4
DESCRIPTION: The IR PSF wings will be evaluated at 5 field points, near field center
and corners in two passbands to verify CEI specifications at 1 and 1.6 um. The F098M
and F153M filters will be used. Full frame images of a moderately bright, isolated star
will be obtained at each field position with a series of increasing exposure times designed
to permit construction of a very high SNR PSF with dynamic range sufficient to evaluate
the wing intensity to >5 arcsec radius. The images will also permit examination of
potential straylight effects and electronic cross-talk. Dark images following the PSF
overexposure will be used to measure image persistence.
IMPLEMENTATION METHOD: SMS
DEPENDENCIES: This must occur after WFC3-24, IR Image Quality.
DURATION: 3 orbits
DATA REQUIREMENTS: 5 full frame, 16 read, STEP-200 IR images (170 MB) will
be generated.
ANALYSES & EXPECTED RESULTS: A high dynamic range PSF will be
constructed for each of the 5 field positions and azimuthal average intensities will be
computed to compare with the CEI specs. Images will be inspected for straylight and
electronic cross-talk artifacts. Dark images following the PSF overexposure will be used
to measure image persistence.
COMMENTS:
AUTHOR/telephone/email: George Hartig/x4966/hartig@stsci.edu
DATE: 25 Jan 2008
ACTIVITY TITLE: WFC3 UVIS Pointing Stability
ID: WFC3-27 (11440)
APPLICABLE SMOV REQUIREMENTS: Verify CEI specifications for stability,
which call for less than 10 mas (0.25 pix) of drift on the UVIS channel in 200 min
(approximately 2 orbits).
DESCRIPTION: Observe a crowded star field for 2 orbits with a series short exposures
on the UVIS channel, using subarrays to minimize time lost to buffer dumps. The
exposures will use the F814W filter. Iterate this 2-orbit series for 3 distinct situations: (1)
after sitting at a constant attitude for 10 orbits, (2) immediately following a slew from hot
to cold attitude (after we were sitting at a hot attitude for 10 orbits), and (3) immediately
following a slew from cold to hot attitude (after we were sitting at a cold attitude for 10
orbits). When the date of these observations is firm, appropriate targets corresponding to
hot and cold attitudes need to be selected from Bill Harris’s list of globular clusters.
There are 41 globular clusters within 15 kpc of the Sun at low extinction (AV < 1 mag),
and these give a well-sampled range of right ascension. The Phase II for this program
will be straightforward, but it needs to be tied to other programs that will give the
appropriate thermal attitude.
IMPLEMENTATION METHOD: Phase II and SMS, with appropriate instructions for
off-nominal roll as needed to achieve proper thermal attitude.
DEPENDENCIES: For each of the three cases, we need to find other calibration
programs that can be grouped with this program to give the required time at a given
attitude (thermal condition) prior to the exposures measuring stability. Cases 1 & 2 or 1
& 3 could be tied together, in principle. Initial alignment should already be completed.
DURATION: 6 orbits (excluding time spent at a given attitude prior to execution)
DATA REQUIREMENTS: 88 UVIS images (400x400 pix, 10-sec) per 2-orbit visit.
ANALYSES & EXPECTED RESULTS: Remove cosmic rays (by stacking images),
co-add all images, create source list from the sum, centroid on those sources in each
individual exposure that have appropriate signal-to-noise, measure drift from centroids.
COMMENTS: This program is not the same as that done for ACS, where the WFC and
HRC channels were each pointed at isolated bright stars for ~1 day of exposures.
AUTHOR/telephone/email: Tom Brown tbrown@stsci.edu x4902
DATE: 2/5/2008
ACTIVITY TITLE: WFC3 IR Pointing Stability
ID: WFC3-28 (11441)
APPLICABLE SMOV REQUIREMENTS: Verify CEI specifications for stability,
which call for less than 20 mas (0.16 pix) of drift on the IR channel in 200 min
(approximately 2 orbits).
DESCRIPTION: Observe a crowded star field for 2 orbits with a series short exposures
on the IR channel, using subarrays to minimize time lost to buffer dumps. The exposures
will use the F105W filter. Iterate this 2-orbit series for 3 distinct situations: (1) after
sitting at a constant attitude for 10 orbits, (2) immediately following a slew from hot to
cold attitude (after we were sitting at a hot attitude for 10 orbits), and (3) immediately
following a slew from cold to hot attitude (after we were sitting at a cold attitude for 10
orbits). When the date of these observations is firm, appropriate targets corresponding to
hot and cold attitudes need to be selected from Bill Harris’s list of globular clusters.
There are 41 globular clusters within 15 kpc of the Sun at low extinction (AV < 1 mag),
and these give a well-sampled range of right ascension. The Phase II for this program
will be straightforward, but it needs to be tied to other programs that will give the
appropriate thermal attitude.
IMPLEMENTATION METHOD: Phase II and SMS, with appropriate instructions for
off-nominal roll as needed to achieve proper thermal attitude.
DEPENDENCIES: For each of the three cases, we need to find other calibration
programs that can be grouped with this program to give the required time at a given
attitude (thermal condition) prior to the exposures measuring stability. Cases 1 & 2 or 1
& 3 could be tied together, in principle. Initial alignment should already be completed.
DURATION: 6 orbits (excluding time spent at a given attitude prior to execution)
DATA REQUIREMENTS: 170 IR images (RAPID, NSAMP=6, 256x256 pix) per 2orbit visit.
ANALYSES & EXPECTED RESULTS: Remove cosmic rays (by fitting the ramp), coadd all images, create source list from the sum, centroid on those sources in each
individual exposure that have appropriate signal-to-noise, measure drift from centroids.
COMMENTS: This program is not the same as that done for ACS, where the WFC and
HRC channels were each pointed at isolated bright stars for ~1 day of exposures.
AUTHOR/telephone/email: Tom Brown tbrown@stsci.edu x4902
DATE: 2/05/2008
ACTIVITY TITLE: FGS-UVIS Alignment
ID: WFC3-29 (11442)
APPLICABLE SMOV REQUIREMENTS: 1.3.2
DESCRIPTION: Images of an area near the center of the open cluster NGC-188, an
astrometric field, will be obtained with the UVIS detector using astrometric guidestars.
The target, previously used for the analogous ACS calibration, will be observed with
POS-TARGs ~ (0,0), (0,15), and (15,0). The FGS (V2-V3) positions of the astrometric
stars in each field will be computed by HST Flight Operations at GSFC. The POSTARG offsets will be used to corroborate the plate scales and orientations of the images
in the FGS frame. Measurement of stellar positions on the detector will be used to map
the UVIS detector coordinate frame to the FGS frame. Image quality over the field will
also be assessed to verify the final adjustments to the corrector mechanisms from
program WFC3-021 (UVIS Fine Alignment). A filter with a compact PSF (F410M) will
be used.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: WFC3-021 (UVIS Fine Alignment)
DURATION: 1 external orbit
DATA REQUIREMENTS: 3 positions * 2 to 4 exposures * 34 MB = up to 408 MB
ANALYSES & EXPECTED RESULTS: Centroid positions of all astrometric stars in
each field will be determined to an accuracy of < 0.5 pixel. These centroids will then be
related to their FGS frame (V2-V3) positions. Aperture orientations and plate scales will
be corroborated with the image position changes between the POS-TARG offset images.
The SIAF aperture descriptions will be updated. Results pertinent to the revision of the
geometric distortion analysis will be incorporated into the analysis of program WFC3031 (UVIS Plate Scale).
COMMENTS: The FGS (V2-V3) positions of the astrometric stars in each field will be
computed by HST Flight Operations at GSFC and must be delivered promptly.
AUTHOR/telephone/email: Linda Dressel 410-338-4376 dressel@stsci.edu
DATE: 20 December 2007
ACTIVITY TITLE: FGS-IR Alignment
ID: WFC3-30 (11443)
APPLICABLE SMOV REQUIREMENTS: 1.3.2
DESCRIPTION: Images of an area near the center of the open cluster NGC-188, an
astrometric field, will be obtained with the IR detector using astrometric guidestars. The
target, previously used for the analogous ACS calibration, will be observed with POSTARGs ~ (0,0), (0,15), and (15,0). The FGS (V2-V3) positions of the astrometric stars
in each field will be computed by HST Flight Operations at GSFC. The POS-TARG
offsets will be used to corroborate the plate scales and orientations of the images in the
FGS frame. Measurement of stellar positions on the detector will be used to map the IR
detector coordinate frame to the FGS frame. Image quality over the field will also be
assessed to verify the final adjustments to the corrector mechanisms from program
WFC3-022 (IR Fine Alignment). A filter with a compact PSF (F098M) will be used.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: WFC3-022 (IR Fine Alignment)
DURATION: 1 external orbit
DATA REQUIREMENTS: 3 positions * 4 dither steps * up to 32 MB (16 readouts) =
up to 384 MB
ANALYSES & EXPECTED RESULTS: Centroid positions of all astrometric stars in
each field will be determined to an accuracy of < 0.5 pixel. These centroids will then be
related to their FGS frame (V2-V3) positions. Aperture orientations and plate scales will
be corroborated with the image position changes between the POS-TARG offset images.
The SIAF aperture descriptions will be updated. Results pertinent to the revision of the
geometric distortion analysis will be incorporated into the analysis of program WFC3032 (IR Plate Scale).
COMMENTS: The FGS (V2-V3) positions of the astrometric stars in each field will be
computed by HST Flight Operations at GSFC and must be delivered promptly.
AUTHOR/telephone/email: Linda Dressel 410-338-4376 dressel@stsci.edu
DATE: 20 December 2007
ACTIVITY TITLE: UVIS Plate Scale
ID: WFC3-31 (11444)
APPLICABLE SMOV REQUIREMENTS: 1.3.1
DESCRIPTION: The geometric scale factors and distortion of the UVIS detector will
be measured using multiple pointing observations of the globular cluster 47 Tucanae
(NGC 104) to image moderately dense stellar fields. ~20 pointings will be used to
sample a range of spatial scales. Care will be taken to choose fields where all pointings
can be obtained with a single set of astrometric guide stars, allowing the plate scale to be
accurately determined. A filter with a compact PSF (F410M) will be used.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: WFC3-021 (UVIS Fine Alignment)
DURATION: 4 consecutive external orbits
DATA REQUIREMENTS: 20 pointings * 34 MB = 680 MB
ANALYSES & EXPECTED RESULTS: Centroid position of stars will be used to tie
down the geometric distortion to about 0.2 pixels across the field of each detector. Our
analysis method is based on that used by the ACS team. It will determine the relative
offsets of the pointings in pixels and measure the geometric distortion in a completely
self-consistent manner.
COMMENTS:
AUTHOR/telephone/email: Linda Dressel 410-338-4376 dressel@stsci.edu
DATE: 20 December 2007
ACTIVITY TITLE: IR Plate Scale
ID: WFC3-32 (11445)
APPLICABLE SMOV REQUIREMENTS: 1.3.1
DESCRIPTION: The geometric scale factors and distortion of the IR detector will be
measured using multiple pointing observations of the globular cluster 47 Tucanae (NGC
104) to image moderately dense stellar fields. ~20 pointings will be used to sample a
range of spatial scales. Care will be taken to choose fields where all pointings can be
obtained with a single set of astrometric guide stars, allowing the plate scale to be
accurately determined. A filter with a compact PSF (F098M) will be used.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: WFC3-022 (IR Fine Alignment)
DURATION: 4 consecutive external orbits
DATA REQUIREMENTS: 20 pointings * 1 or 2 exposures (dither steps) * up to 34
MB (16 readouts) = up to 1360 MB
ANALYSES & EXPECTED RESULTS: Centroid position of stars will be used to tie
down the geometric distortion to about 0.2 pixels across the field of each detector. Our
analysis method is based on that used by the ACS team. It will determine the relative
offsets of the pointings in pixels and measure the geometric distortion in a completely
self-consistent manner.
COMMENTS:
AUTHOR/telephone/email: Linda Dressel 410-338-4376 dressel@stsci.edu
DATE: 20 December 2007
ACTIVITY TITLE: UVIS dark current, readnoise, and CTE
ID: WFC3-33 (11446)
APPLICABLE SMOV REQUIREMENTS: 1.3.3
DESCRIPTION: This proposal obtains full-frame, four-amp readout bias and dark
frames at regularly-spaced intervals throughout SMOV in order to assess and monitor
dark current, bad (warm, hot, dead) pixels, and readnoise. In addition, a set of internals
using the WFC3 calsystem are taken to provide a baseline CTE measurement. The EPER,
or extended pixel edge response, technique will be employed: exposures are acquired at a
variety of different signal levels and the CTE is measured from the profile of the trailing
overscan region (poor CTE will result in significant charge in the overscan). The EPER
images are acquired via the CTE=EPER parameter in the phase II proposal; these images
have non-standard readouts with significantly larger areas of overscan to facilitate the
CTE measurements. While the CTE in the WFC3 CCDs is expected to be excellent
initially, radiation damage on-orbit will cause the CTE to degrade over time; the results
from this program will serve as a baseline for future CTE monitoring.
IMPLEMENTATION METHOD: Standard Phase II proposal and commanding.
DEPENDENCIES: Can not be run until after successful completion of WF16, UVIS
TEC performance test. Bias/dark orbits should be spread relatively evenly throughout
SMOV (they should not be run close in time to the WF18 anneal bias/darks).
DURATION: 24 internal orbits total (22 for biases/darks, where each orbit contains 2
biases and 1 dark, and 2 orbits for EPER images). No external targets are required.
DATA REQUIREMENTS:
2191.2 Mbytes of biases/darks and 372 Mbytes of EPER imaging
ANALYSES & EXPECTED RESULTS
Readnoise will be measured from the overscan regions of individual bias frames as well
as from science pixel areas within difference images of pairs of biases. Biases will be
used in conjunction with biases from other programs (e.g., WF06) to generate a superbias
and verify permanent defects such as blocked columns. Dark current levels, average rates
as well as hot and warm pixel levels, will be determined from the dark frames. Darks will
be used in conjunction with darks from other programs (e.g., WF06) to generate a
superdark and maintain a tabulated list of hot pixels. CTE results, as measured from the
internal flats, will be compared to those from groundbased tests and used as a baseline for
future CTE monitoring.
COMMENTS:
AUTHOR/telephone/email: S. Baggett / 410-338-5054 / sbaggett@stsci.edu
DATE: Dec 20, 2007
ACTIVITY TITLE: IR dark current, readnoise, and background
ID: WFC3-34 (11447)
APPLICABLE SMOV REQUIREMENTS: L.10.4.1.3.4
DESCRIPTION: This proposal obtains full-frame, four-amp readout images. Unilluminated internals are taken at regularly spaced intervals throughout SMOV in order to
assess and monitor readnoise and dark current (of both light-sensitive pixels and
reference pixels), and bad (warm, hot, dead, variable) pixels. In addition, externals aimed
at fields with sparse stellar density are taken to measure diffuse background light.
IMPLEMENTATION METHOD: Standard Phase II proposal and commanding.
DEPENDENCIES: Execute only after successful completion of WF17, IR TEC
performance test. Orbits should be spread relatively evenly throughout SMOV – to
quantify stability over at least a 30-day baseline. (If analysis of WF36, IR SAA Passage
Behavior, indicates charge latency much larger than anticipated, then subsequent
exposures of WFC3-34 may need to be executed not immediately subsequent to activities
that illuminate the IR detector with a large irradiance (e.g. flats, bright star clusters).)
DURATION: 20 internal orbits total (20 repetitions of a 1-orbit plan that acquires a
long-exposure dark and a before and after readnoise measurement). For backgrounds, 6
external orbits are required, in which each orbit contains ~5 exposures.
DATA REQUIREMENTS:
1120 Mbytes of darks and read-noise; 864 Mbytes of backgrounds.
ANALYSES & EXPECTED RESULTS
Readnoise and dark current will be measured from differences of short exposures
(readnoise) and long exposures (dark current). The analysis will examine both reference
pixels and light-sensitive pixels to quantify differences if any between them and to assess
which reference pixels give the same readnoise and dark current in un-illuminated (this
activity) and illuminated images (from other activities). Hysteresis and interpixel
capacitance, etc, are expected to make certain reference pixels more useful than others.
Dark current levels, average rates as well as hot and warm pixel levels, will be
determined from the dark frames. Darks will be used in conjunction with darks from
other programs (e.g., WF07) to generate a superdark and maintain a tabulated list of hot
pixels. Background light, as measured for each W&M filter from external images of a
single field of medium zodiacal light level, will be compared to those anticipated from
known sources (e.g. Zodiacal light) and WFC3 throughput (cf. Table 7.12 of Instrument
Handbook).
COMMENTS:
AUTHOR/telephone/email: P. McCullough / 410-338-5068 / pmcc@stsci.edu
DATE: Jan 10, 2008
NOTES:
Current plan for darks and readnoise images is 20 repetitions of the 3-exposure sequence
in the table below, which requires (15+20+2803+20+15+20)= 2893 sec = 48 min = 1
orbit) to execute and 56 MB:
SampSeq
RAPID
SPARS200
RAPID
NSAMP Exposure
(sec)
5
15
5
15
2803
15
Data Vol
(MB)
Purpose
12
32
12
readnoise
dark current
readnoise
Current plan for background externals:
Filter Estimated Meas. Flux
from Zodi (e-/sec/pix)
ADU/pix SampSeq NSAMP Time Repeats Data Vol
from Zodi
each (s)
(MB)
F105W
F110W
F125W
F140W
F160W
0.639
1.053
0.613
0.739
0.455
225
371
216
260
160
SPARS25
SPARS25
SPARS25
SPARS25
SPARS25
15
15
15
15
15
352
352
352
352
352
3
3
3
3
3
96
96
96
96
96
F098M
F127M
F139M
F153M
0.372
0.140
0.122
0.117
261
98
86
82
SPARS50
SPARS50
SPARS50
SPARS50
15
15
15
15
702
702
702
702
3
3
3
3
96
96
96
96
total time =
total MB =
5.07 45-min orbital windows, not including overheads.
864.000 MB.
N(arrow) filters’ background rates will be estimated by analysis from M and W data
gathred as per above table.
ACTIVITY TITLE: UVIS SAA Passage Behavior
ID: WFC3-35 (11448)
APPLICABLE SMOV REQUIREMENTS: 1.3.5
DESCRIPTION: The Southern Atlantic Anomaly (SAA) is the region where the Van
Allen belts intersect the Earth and is distinguished by elevated levels of particle radiation,
(high-energy protons and electrons) which adversely affects the scientific instruments of
low-earth orbit satellites such as HST. Short and long term effects may include: high
cosmic ray (CR) hit rates, high dark and background levels, residual glow and count
rates, damage to the detector lattice, reduced charge transfer efficiency, flip memory bits,
and Single Event Upsets that can suspend the instrument. HST intersects the SAA every
day for 8-9 consecutive orbits, followed by 5-6 SAA-free orbits. When possible, external
HST targets are scheduled such that the Earth’s occultation hides the SAA. For each
instrument, SAA avoidance contours have been empirically defined using on-orbit data.
The SAA contours for WFC3 will be identical to those of WFPC2, labeled SAA-26, at
the beginning of its orbital lifetime. In this program, the behavior of the WFC3 UVIS
CCD through the SAA as well as residual effects following the SAA crossing will be
characterized. The data may help refine the shape of the SAA contours for WFC3.
IMPLEMENTATION METHOD: A series of short darks will be acquired internally
(e.g. parallels) before, during, and after the SAA passage without interruption. At a
minimum, the deepest part of the SAA will be selected for maximum duration and
impact. Very detailed visit level comments will be necessary for scheduling and
coordination.
DEPENDENCIES: SMOV WF3-16: UVIS TEC Performance
DURATION: 2 orbits, one crossing of the SAA in each orbit
DATA REQUIREMENTS: A series of ~9 consecutive 340 sec UVIS darks will be
acquired in each orbit, assuming ~54 min/orbit. The buffer dumps will be in parallel.
ANALYSES & EXPECTED RESULTS: The usual analysis of SAA-impacted dark
frames consists of tracking the CR rate through the passage and comparing it with non
SAA-impacted rates. For other HST instruments, the CR rates are typically several
factors greater in the SAA than outside. The presence (or absence) of short and long term
transients (e.g. glows) will also be verified.
COMMENTS: Ideally, multiple crossings through the SAA are necessary to map out the
CR rates. If two crossings are scheduled, then one should be in the deepest part of the
SAA and the other near the edge (but still inside) the defined avoidance contour.
AUTHOR/telephone/email: André Martel/410-516-8832/martel@pha.jhu.edu
DATE: Dec 13, 2007
ACTIVITY TITLE: IR SAA Passage Behavior
ID: WFC3-36 (11449)
APPLICABLE SMOV REQUIREMENTS: 1.3.5
DESCRIPTION: The Southern Atlantic Anomaly (SAA) is the region where the Van
Allen belts intersect the Earth and is distinguished by elevated levels of particle radiation,
(high-energy protons and electrons) which adversely affects the scientific instruments of
low-earth orbit satellites such as HST. Short and long term effects may include: high
cosmic ray (CR) hit rates, high dark and background levels, residual glow and count
rates, damage to the detector lattice, reduced charge transfer efficiency, flip memory bits,
and Single Event Upsets that can suspend the instrument. HST intersects the SAA every
day for 8-9 consecutive orbits, followed by 5-6 SAA-free orbits. When possible, external
HST targets are scheduled such that the Earth’s occultation hides the SAA. For each
instrument, SAA avoidance contours have been empirically defined using on-orbit data.
The SAA contours for WFC3 will be identical to those of WFPC2, labeled SAA-26, at
the beginning of its orbital lifetime. In this program, the behavior of the WFC3 IR CCD
through the SAA as well as residual effects following the SAA crossing will be
characterized. The data may help refine the shape of the SAA contours for WFC3.
IMPLEMENTATION METHOD: A series of short darks will be acquired internally
(e.g. parallels) before, during, and after the SAA passage without interruption. At a
minimum, the deepest part of the SAA will be selected for maximum duration and
impact. Very detailed visit level comments will be necessary for scheduling and
coordination.
DEPENDENCIES: SMOV WF3-17: IR TEC Performance
DURATION: 2 orbits, one crossing of the SAA in each orbit
DATA REQUIREMENTS: A series of ~9 consecutive 350 sec IR darks will be
acquired in each orbit, assuming ~54 min/orbit. The buffer dumps will be in parallel.
ANALYSES & EXPECTED RESULTS: The usual analysis of SAA-impacted dark
frames consists of tracking the CR rate through the passage and comparing it with non
SAA-impacted rates. For other HST instruments, the CR rates are typically several
factors greater in the SAA than outside. The presence (or absence) of short and long term
transients (e.g. glows) will also be verified.
COMMENTS: Ideally, multiple crossings through the SAA are necessary to map out the
CR rates. If two crossings are scheduled, then one should be in the deepest part of the
SAA and the other near the edge (but still inside) the defined avoidance contour.
AUTHOR/telephone/email: André Martel/410-516-8832/martel@pha.jhu.edu
DATE: Dec 13, 2007
ACTIVITY TITLE: UVIS Photometric Zero Points
ID: WFC3-037 (11450)
APPLICABLE SMOV REQUIREMENTS: WFC3 will provide high photometric
performance over the full wavelength range covered by the instrument, with filter
limiting magnitudes of at least 25.5 (U), 26.4 (B), 27.1 (V), 26.3 (R), and 26.1 (I) mag.
WFC3 will provide high photometric stability, with the variation over 1 month being less
than 5% at 200-300 nm, less than 3% at 300-400 nm, and less than 1% from 400-1000
nm.
DESCRIPTION: Observe one of three photometric standards (G191B2B, GD153, or
GD71), depending upon time of year, in each of the 16 priority-1 filters (F218W, F225W,
F275W, F300X, F336W, F350LP, F390W, F438W, F475W, F475X, F555W, F600LP,
F606W, F625W, F775W, F814W), 20 priority-2 filters (F280N, F343N, F373N, F390M,
F395N, F410M, F467M, F469N, F487N, F502N, F547M, F621M, F645N, F656N,
F658N, F673N, F689M, F763M, F845M, F953N) and any additional filters used in
EROs. Obtain two short images in each of these filters, using subarrays, with a small
dither (~10.5 pixels) between exposures, allowing rejection of cosmic rays and detector
artifacts. To monitor stability in 6 key filters (F225W, F336W, F438W, F555W, F606W,
F814W), a subset of these observations will be repeated on timescales of 1, 7, and 30
days.
IMPLEMENTATION METHOD: Phase II and SMS.
DEPENDENCIES: WFC3-14 (Shutter test) and WFC3-21 (UVIS Fine Alignment)
DURATION: 10 orbits
DATA REQUIREMENTS: 116 800x800 pixel images.
ANALYSES & EXPECTED RESULTS: Aperture photometry and comparison to
expectations from both thermal vacuum tests and component throughputs.
COMMENTS: None.
AUTHOR/telephone/email: Tom Brown tbrown@stsci.edu x4902
DATE: 12/11/07
ACTIVITY TITLE: IR Photometric Zero Points
ID: WFC3-38 (11451)
APPLICABLE SMOV REQUIREMENTS: WFC3 will provide high photometric
performance over the full wavelength range covered by the instrument, with filter
limiting magnitudes of at least 25.5 (J), and 24.3 (H) mag. WFC3 will provide high
photometric stability, with the variation over 1 month being less than 1% from 1-2
microns.
DESCRIPTION: Observe one of three blue photometric standards (G191B2B, GD153,
or GD71) and one red photometric standard (P330E), in each of the WFC3/IR filters.
Obtain two short images in each of these filters, using subarrays, with a small dither
(~10.5 pixels) between exposures, allowing rejection of cosmic rays and detector
artifacts. To monitor stability in 5 key filters (F105W, F110W, F125W, F140W,
F160W), a subset of these observations will be repeated on timescales of 1, 7, and 30
days.
IMPLEMENTATION METHOD: Phase II and SMS.
DEPENDENCIES: WFC3-22 (IR Fine Alignment)
DURATION: 8 orbits
DATA REQUIREMENTS: 116 128x128 pixel images with 7 non-destructive reads per
image.
ANALYSES & EXPECTED RESULTS: Aperture photometry and comparison to
expectations from both thermal vacuum tests and component throughputs.
COMMENTS: None.
AUTHOR/telephone/email: Tom Brown tbrown@stsci.edu x4902
DATE: 12/11/07
ACTIVITY TITLE: UVIS Flat Field Uniformity
ID: WFC3-39 (11452)
APPLICABLE SMOV REQUIREMENTS: 1.3.7
DESCRIPTION: The stability and uniformity of the low-frequency flat fields (L-flat) of
the UVIS detector will be assessed by using multiple pointing observations of the
globular cluster 47 Tucanae (NGC104), thus imaging moderately dense stellar fields. By
placing the same star over different portions of the detectors and measuring relative
changes in its brightness, it will be possible to determine local variations in the response
of the detectors.
Based on previous experience with STIS and ACS, it is deemed that a total of nine
different pointings will suffice to provide adequate characterization of the flat field
stability in any given band. For each filter to be tested, the baseline consists of 9
pointings in a grid pattern (useful also for CTE measurements, if needed in the future).
During SMOV, the complement of filters to be tested is limited to the following 6 filters:
F225W, F275W, F336W, F438W, F606W, and F814W.
IMPLEMENTATION METHOD: SMS, stored commanding.
DEPENDENCIES: WF21, UVIS Fine Alignment.
DURATION: 12 external orbits.
DATA REQUIREMENTS: 9 pointings x 6 filters x 34 MB = 1836 MB.
ANALYSES & EXPECTED RESULTS: Standard software will be used to analyze the
flats and verify the stability of the L-flat structure from the dithered observations.
COMMENTS:
AUTHOR/telephone/email: Jessica Kim Quijano/410-338-4786/jkim@stsci.edu
Linda Dressel/410-338-4376/dressel@stsci.edu
DATE: December 15, 2007
ACTIVITY TITLE: IR Flat Field Uniformity
ID: WFC3-40 (11453)
APPLICABLE SMOV REQUIREMENTS: 1.3.7
DESCRIPTION:
Following the lead set by ACS during SMOV3B, we will assess the uniformity
and stability of the low-frequency flat fields of the IR detector. This will be
accomplished by observations at multiple pointings with multiple filters of the globular
cluster 47 Tucanae (NGC104). By placing the same star at multiple locations on the
detector and measuring the relative changes in its brightness, it will be possible to
determine spatial variations in the response of the detector. Based on previous work with
other instruments, a set of 9 pointings should be sufficient to characterize the stability of
the flat field. For each filter to be tested, this set of 9 pointings will form an X pattern on
the detector, with steps of ~10% of the FOV in the x-direction and ~10% of the FOV in
the y-direction between observations. The complement of filters to be tested will be
F105W, F125W, F140W, and F160W.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: WF22 – IR Fine Alignment
DURATION: 10 external orbits.
DATA REQUIREMENTS:
This activity will produce 72 full-frame, IR ramps. (9 positions x 4 filters x 2 ramps).
This implies a total data volume of 2304 MB (32MB per ramp), or 18432 Mbits.
ANALYSES & EXPECTED RESULTS:
Map of low frequency flat field sensitivity variations.
Comments:
Total FOV is 126”x138”…use 10% shifts in X and Y between positions.
POSTARG (0,0), (12,14),(24,28),(-12,-14),(-24,-28),(-12,14),(-24,28),(12,-14),(24,-28)
AUTHOR/telephone/email:
Bryan Hilbert
410-338-4725
Hilbert@stsci.edu
DATE:
12/20/2007
NOTES:
Object position implies 60 minutes of visibility per orbit.
Large range of source brightnesses in 47 Tuc. CMD’s in the literature seem to show that
you get into the majority of the stellar population once you get down to J=18.
For an M2I star (red giant) normalized to J=18, the time to saturate is given by the ETC
as:
F110W – 212 sec
F125W – 347 sec
F140W – 270 sec
F160W – 411 sec
SPARS50 with NSAMP=7 is 302secs, and produces 16MB ramps. Take these in pairs to
avoid having to wait for buffer dumps. The other option would be STEP50 with NSAMP
of 11. This would better sample the brighter stars, so that more of them could be
recovered from early reads before they saturate. The disadvantage would be that the data
collection would be more messy, since the data volume is higher. Might want to just go to
NSAMP 12 at that point (352sec), and dump one at a time. Try NSAMP=12 for all,
except for NSAMP=13 for F160W
Data taken at 9 different positions on the detector, using the POSTARGs above. Using
the STEP50 NSAMP=12 or 13 strategy, including overheads, I find 5.2 orbits to get one
ramp in each filter and at each position.
ACTIVITY TITLE: Characterization of the WFC3 IR Grisms
ID: WFC3-42
APPLICABLE SMOV REQUIREMENTS:
DESCRIPTION: The purpose of this test is to verify the image displacement, spectral
trace and dispersion, and throughput of the WFC3 IR G102 and G141 spectral elements.
Full-frame IR exposures will be obtained of an HST flux standard, such as GD153,
GD171, or G191B2B, at several positions in the field of view for each of the two grisms.
Each observation will include a direct image exposure, using a non-grism filter element,
to allow for measurement of the source location offset between direct and dispersed
images.
Similarly, full-frame IR exposures of a wavelength calibrator, such as PN HB12 or Vy22, will be obtained at several positions in the field of view for each of the two grisms, in
order to verify the wavelength scales of the G102 and G141 grisms and their field
dependence. Two orbits per grism will be needed, for a total of 4 orbits of observing
time.
IMPLEMENTATION METHOD: Stored commanding.
DEPENDENCIES: WFC3-10, WFC3-12. Should be scheduled in advance of any ERO
programs that use the IR grisms.
DURATION: 4 Orbits (external)
DATA REQUIREMENTS: 8 Gbits
ANALYSES & EXPECTED RESULTS: Source location offsets will be measured
between the direct and dispersed images. Extracted spectra of the flux standards will be
ratioed to the known absolute flux distributions of the standard stars to compute
calibration curves for the two grisms. Pixel locations of known features in the wavelength
calibrator spectra will be used to compute the mapping between pixel and wavelength
space (dispersion coefficients).
COMMENTS:
AUTHOR/telephone/email: Howard Bushouse/410-338-4530/bushouse@stsci.edu
DATE: May 12, 2008
ACTIVITY TITLE: UVIS Bowtie Monitor
ID: WFC3-44
APPLICABLE SMOV REQUIREMENTS:
N/A
DESCRIPTION:
The UVIS detector was observed during ground testing to occasionally exhibit flat field
and dark variations with a “bowtie” pattern. These variations are most significant as ~1%
flat field (gain) variations across the field of view. It is believed that this represents a
state or condition into which the detector can be for reasons and under circumstances
which are not currently understood. It is also very unlikely that most science observations
will determine the state (bowtie or no-bowtie) of the detector. Ground test data indicates
that this state is long lived (many hours to ~one day). Hysteresis or memory of past light
exposure is also associated with this state.
Recent evidence suggests that exposing the detector to ~100k electrons may quench this
state. This proposal obtains an internal flat field sequence of three exposures: one at 2x
full well and two at 0.5x full well. Each exposure is 3x3 binned to reduce the data volume
requirement.
IMPLEMENTATION METHOD:
Stored commanding
DEPENDENCIES: WF04 – UVIS activation
DURATION: 200 internal visits
DATA REQUIREMENTS:
This activity will produce 600 3x3 binned UVIS images. This implies a total data
volume of 4x600 = 2400 MB.
ANALYSES & EXPECTED RESULTS:
Knowledge of the bowtie state of the UVIS detector. Trending of bowtie state frequency
following turn-on and after anneals.
Comments:
Schedule to execute 2 times per day.
AUTHOR/telephone/email:
John W. MacKenty
410-338-4559
mackenty@stsci.edu
DATE:
07/24/2008
NOTES:
none