Instrument Science Report WFPC2 2003-01
WFPC2 Cycle 9 Closure Report
A. M. Koekemoer, S. Baggett, S. Casertano, S. Gonzaga, I. Heyer,
and the WFPC2 Group
April 7, 2003
ABSTRACT
This report describes in detail the WFPC2 observations used to maintain and improve the
quality of WFPC2 calibrations during Cycle 9, and their status at completion of the Cycle.
1. Introduction
The Cycle 9 Calibration Plan for WFPC2 (Baggett et al. 2000, ISR-00-01) outlines the
major goals of the various observational programs aimed at calibrating WFPC2 during
Cycle 9, which spanned the time interval from June 30, 2000 to July 31, 2001. The
WFPC2 calibration programs carried out during that period fall essentially into two categories: routine monitoring programs aimed at calibrating basic characteristics of the
camera (for example, flat fields, photometric throughput, and electronic properties such as
bias and dark current); and special programs aimed at performing new tests to improve our
understanding in several key areas, such as the effects of CTE, checks for redleaks in the
UV filters, and wavelength stability of the narrowband and linear ramp filters.
A major event for WFPC2 during Cycle 9 was the WFPC2 Shutter Anomaly, which
manifested itself in the form of errors reported in the behavior of the shutter blade B in
WFPC2 during the timeframe August to October 2000, with the eventual culmination of a
safing of WFPC2 on November 1, 2000. A tiger team investigating this anomaly concluded that long-term aging had caused reduced photon coupling in the LED used in the
shutter position sensor, and this was responsible for the errors. A change to the flight software was implemented that would allow a longer read time for the shutter sensor, thereby
ensuring that sufficient light was captured to produce an accurate reading of the shutter
Instrument Science Report WFPC2 2003-01
position. The RAM patch was uploaded and WFPC2 was successfully recovered on
November 7, 2000. No further instances of this anomaly have since occurred.
Monitoring Programs
Similarly to previous Cycles, a substantial part of the Cycle 9 calibration program consisted of routine monitoring observations and decontamination procedures (decons). The
decons were performed on a monthly basis to remove UV contaminants from the CCD
windows and anneal hot pixels. As in previous Cycles, each decon visit contained associated observations to monitor the performance of the cameras by means of external
observations of the WFPC2 standard white dwarf GRW+70d5824 in a range of filters.
This allowed efficient tracking of the overall long-term photometric throughput of the
camera, the monthly throughput decline rates due to UV contaminant buildup on the CCD
windows, and the return to nominal throughput after each decon. We also monitored the
PSF properties at different wavelengths, the OTA focus, and the general health and performance of the cameras. In addition, since Cycle 8, each decon visit has also contained
associated internal exposures (including darks, biases, internal flats, and kspots), and
Earth flats, aimed at monitoring the general health and performance of basic properties of
the cameras. As this resulted in an excessively long proposal, the decon proposal was split
into four parts (8822 - 8825; see Table 1).
Other continuing programs from Cycle 8 consisted of the standard darks program
8811 (six darks per week, used for reference files and hot pixel lists), the supplemental
darks program 8826-8828 (up to 3 darks per day, low priority, for archive only), and the
weekly internal monitor (biases and kspots). The Earth flat program (8815)was also
extended, to allow tracking and correction for changes in the flatfield. A separate program
of UV Earthflats (8816) was implemented as part of the routine set of monitoring programs. Following the general plans of previous cycles, streak flats in a subset of filters
were obtained to construct superflats for generating the pipeline flats.
The monitoring proposals also included the astrometric monitor, intflat sweeps, and
linearity checks. Data from the astrometry program, which also included internal kspots
observations, are being used to measure chip position shifts and changes in the astrometry
(Casertano et al. 2001, ISR-01-10). Internal flats, taken for verification of the pixel to pixel
flatfield response, are also being analyzed; some of these have been useful in determining
the repeatability of the shutter blade mechanism.
Special Programs
Two special programs that were continued from Cycle 8 consisted of the photometric
and PSF checks, each of which were done once during Cycle 9. The photometric check
(8818) was aimed at providing data that could be used to verify the zeropoints and contamination rates in the non-standard filters. The PSF check (8819) consisted of dithered
2
Instrument Science Report WFPC2 2003-01
observations of the crowded ω Cen field in the standard wide-band photometric filters,
providing a high S/N, critically sampled PSF across the full WFPC2 field and over most of
the visible wavelength regime. The data from this program was aimed at supporting PSF
fitting photometry, testing PSF subtraction and dithering techniques (e.g., effects of OTA
breathing and gain), and serve as a source of PSFs for the online WFPC2 PSF library.
Three new special programs for Cycle 9 were the redleak check, CTE calibration, and
a wavelength stability check of the narrowband and linear ramp filters. The redleak check
(8814) consisted of observing two solar analog targets for which existing FOS spectrophotometry is available, and comparing the measured countrates to synphot predictions from
the UV proper and from the red leak, to investigate some of the discrepancies reported
thus far in the estimated red leak contributions.
The CTE program consisted of two parts, namely a monitor component (essentially an
extension of the Cycle 8 CTE monitor 8447), and a suite of observations aimed at providing an absolute calibration of CTE by allowing a comparison with a ground-based CTE
program. The HST observations of three globular clusters were used to determine: (1) an
independent, absolute calibration of the current CTE effect; (2) a measure of time variations of CTE by comparison with archival HST data; and (3) observations bracketing the
range of signal and background values in science images (200 to 100 electrons per star, on
backgrounds from 10 to 300 electrons). In addition, comparison of the HST and groundbased datasets would provide a direct verification of the zeropoints for many WFPC2
observations. Results from this program are described by Heyer, 2001, ISR-01-09.
The wavelength stability check for narrowband and linear ramp filters (8820) was carried out by obtaining on-orbit ramp filter VISFLAT exposures, crossed and uncrossed with
narrowband filters, to constrain the wavelength and transverse calibration of the ramps relative to the narrowband filters. Comparison with Cycle 4 data would allow evaluation of
whether the filter properties have evolved with time due to annealing or shrinkage of the
thin film materials. In addition, four external orbits of an extended emission-line source
were obtained to provide an absolute test for changes in the ramp filters.
2. Format
Table 1 summarizes the program as executed during Cycle 9, including proposal titles
and numbers, frequency with which the program was executed, orbits used (numbers provided by PRESTO), analysis products, accuracy of the results, and general notes. The
remainder of the report contains details for every proposal: the plan is presented on the left
of each page and results are summarized on the right. The proposal pages are intentionally
in landscape format, to facilitate comparison of the plan and results. Finally, a detailed
bibliography is provided, listing new documents since the last closure report and pointers
to items of general interest. All the Phase II versions of the proposals can be viewed at:
http://www.stsci.edu/hst/scheduling/program_information/
3
Table 1: Summary of WFPC2 Cycle 9 Calibrations
Time (orbits)
ID
Proposal Title
Frequency
Scheduling
Accuracy
Products
Required
Required
“External” “Internal”
Notes
Routine Monitoring Programs
8822 - WFPC2 Decons & Associated
8825 Observations
99 [82]
every 28 d
Synphot,
CDBS
weekly
228 [366]
every 7 d
CDBS
8826 - Supplemental Darks (8460, 8461)
8828
0-3/day
1254 [1282] anytime
8812
Internal Monitor
weekly
68 [76]
every 7d
CDBS
8815
Earth Flats
continuous
224 [210]
mid-cycle
CDBS
0.3%
8816
UV Earth Flats
continuous 2
306 [400]
mid-cycle
CDBS
3-10%
Outsourcing candidate
8813
Astrometric Monitor
2/cycle
early & late ISR
0.05”
Omega Cen as well as K-spots
8817
Intflat Sweep and Linearity Test
1/cycle
mid-cycle
0.3%
8811
1-2/4 wks 29 [30]
Standard Darks
2
21
1-2%
1 e-/hr
n/a
Decons, phot. & focus monitor,
internals, UV throughput, VISFLATs,
and UV FLATs
Also hot pixel lists for WWW.
For archive only, no analysis provided
0.8e-/pixel Includes INTFLAT monitor, for
possible future preflashed observations.
TIR
Special Calibration Programs
8818
Photometric Characterization
1
2
mid-cycle
8819
PSF Characterization
1
6
late in cycle CDBS
8814
Redleak Check
1
3
mid-cycle
8821
CTE - Monitor and Absolute Calibration 1
15
mid/late cyc ISR
0.01 mag
Includes monitor as well as followup to
groundbased observations. Outsourcing
candidate.
8820
Wavelength Stability of Narrow-band
and Linear Ramp Filters
4
mid/late cyc CDBS,
ISR
2Å
Check of wavelength/aperture mapping
and test for changes in LRFs.
~10% reserve for unexpected items
1
15
7
TOTAL TIME (including all executions) 70 [71]
ISR
2-3%
GRW+70D5824; nonstandard filters
10%
Omega Cen; standard broadband filters.
Synphot, 2%
CDBS
Solar analogs used to measure UV filter
redleaks.
Placeholder.
2215 [2452]
Orbits listed in Time column are orbits actually used; [] marks initial requested number when different from the used orbits. Differences are discussed under
each individual proposal’s summary.
4
Proposal ID 8822-8825: WFPC2 Cycle 9 Decontaminations and Associated Observations
Plan
Results
Purpose Monthly WFPC2 decons. Other programs tied to decons are
also included: photometric stability check, focus monitor, preand post-decon internals, UV throughput checks, VISFLAT
sweep, and internal UV flat check.
Modifications The program had 30 approved external orbits, of which one did
not execute due to the Shutter Anomaly. An additional 17 internal orbits were used to verify WFPC2 behavior after recovery
from the Shutter Anomaly.
Description Decontamination:UV-blocking contaminants removed and hot
pixels annealed by warming the CCDs to +20C for 6 hours.
Execution Nominal, apart from the above modifications related to the Shutter Anomaly.
Internals: intflats, biases, darks & kspots, before/after decons.
Photometric Monitor: GRW+70d5824 is observed after each
decon and before every other decon: (1) F170W in all chips to
monitor far UV contamination. (2) As many as possible of
F160BW, F218W, F255W, F336W, F439W, F555W, F814W
will be observed in a different chip each month.
Focus Monitor: two PC, F555W observations of
GRW+70d5824 will be taken during every photometric monitoring orbit (one at orbit start, one near orbit end).
UV Throughput: PC & WF3 UV observations in most UV filters, popular UV filters in all chips, to verify that the UV spectral response curve is unchanged. In addition, two PC, F555W
observations will be included as an extra focus monitor.
Internal UV flatfields: obtained with the CAL channel’s ultraviolet lamp (UVFLAT) using the UV filters F122M, F170W,
F160BW, F185W, & F336W. The UV flats are used to monitor
UV flatfield stability and the stability of the F160BW filter by
using F170W as the control. The F336W ratio of VISFLAT to
UVFLAT provides a diagnostic of the UV flatfield degradation
& ties the UVFLAT and VISFLAT flatfield patterns. Two supplemental dark frames must be obtained immediately after each
use of the lamp to check for possible after-images.
Fraction 100%
GO/GTO
Programs
Supported
Time-line Executed throughout Cycle 9.
5
Plan
Resources Total of 30 external and 82 internal orbits. Request covers thirRequired: teen decons plus three extra decons. External orbits needed:
Observation 24 orbits for photometric monitoring,
4 orbits for UV throughput,
2 orbits for UV flats monitor (non-pointed, but displaces
WFPC2 science because of timing requirements) plus occultation periods before and after each orbit,
2 internal orbits for VISFLAT sweep and
80 internal orbits for INTFLAT monitoring.
Results
Resources 29 external orbits and 99 internal orbits.
Used:
Observation
Products SYNPHOT, CDBS, Instrument Handbook, TIPS meetings,
WWW reports, TIR, ISR; new UV flatfields if changes are
detected.
Products WFPC2 Instrument Handbook, updates on the WWW photometry page, presentations at TIPS meetings.
The PC, F555W images of the standard star were used in monitoring focus and determining secondary mirror moves necessary
to maintain focus; results are regularly posted to WWW Observatory Support pages.
Decon dates are also posted regularly to WFPC2 History File on
WWW; list of all decons done to date can be found in Table 2.
Accuracy Photometry: less than 2% discrepancy between results, 1% rms
Goals expected. Focus measurement: 1.5 mic accuracy with a goal of 1
mic. UV throughput: better than 3%. Flatfield: temporal variations monitored at 1% level. Gain ratios: stable to better than
0.1%. UV flats: About 2-8% pixel-to-pixel expected (filter
dependent). VISFLATs: stable to better than 1% in overall level
and spatial variations (after correcting for lamp degradation).
Contamination effects should be < 1%.
Accuracy Decon procedures were successful, restoring WFPC2 UV
Achieved throughput, fluctuations are 2% or less peak to peak longwards
of F336W (see Fig. 1, taken from WWW Photometric Monitoring memo; Gonzaga et al.) and annealing hot pixels. The focus
monitor results are routinely reported on the WWW Observatory Support pages (Lallo et al.); typically, ~1 micron RMS of
secondary mirror motion is achieved.
6
Plan
Scheduling& Upon request, all timing requirements have been hardcoded via
Special GROUP-WITHIN and BETWEEN special requirements
Requirements Decons: every 4 weeks. Photometry: Observations are tied to
within +/- 1 week of decons. Darks: around decon, these are
taken NON-INT to prevent residual image problems.
Results
Continuation
Plans
VISFLAT sweep must be done with minimum number of lamp
cycles to prevent further degradation of the lamp.
UV flats: To prevent excessive degradation of the UV lamp, the
SU duration for each UVFLAT visit should be kept the same as
that in cycle 8 (prop. 8449); the lamp should not remain on for
periods of time longer than those used in Cycles 7 & 8. Due to
timing requirements, each visit covers a 2-hour time span--one
visibility period and two occultation periods; other instruments
can be used during this period.
7
Figure 1: Photometric monitoring results for PC1 and WF3, from Feb 1994 to July 2002; plot is regularly updated online (WWW Photometric Monitoring
memo: http://www.stsci.edu/instruments/wfpc2/wfpc2_resources.html). Note the UV contamination effects in the bluer filters and restoration to nominal
UV throughput after each decon (WFPC2 Long-Term Photometric Stability, ISR 98-03, Baggett & Gonzaga).
8
Table 2: WFPC2 decontamination dates, taken from the WFPC2 History Memo on the WWW (Baggett & Wiggs).
date
MJD
t
1994
date
MJD
t
date
10 Mar 00:21
50152.0147
6
1998
MJD
t
date
Dec 28 19:43
MJD
t
51540.8215
6
51546.0674
6
date
MJD
t
Sep 5 05:33
52157.2317
6
Oct 5 06:44
52187.2807
6
Nov 2 04:46
52215.1986
6
Feb 22 11:37
49405.4840
6
02 Apr 00:16
50175.0111
6
Jan 08 00:03
50821.0025
6
2000
Mar 24 11:08
49435.4639
6
04 May 17:09
50207.7146
6
Feb 01 19:15
50821.0025
6
Jan 03 01:37
Apr 24 00:49
49466.0340
6
28 May 06:16
50231.2614
6
Mar 06 09:18
50878.3877
6
Jan 17 16:27
51560.6854
6
Nov 30 08:50 52243.3681
28
May 23 15:00
49495.6250
5.5
22 Jun 22:15
50256.9277
6
Mar 31 12:54
50903.5376
6
Jan 31 15:48
51574.6583
6
Dec 27 03:25
52270.1427
6
Jun 13 11:02
49516.4597
12
28 Jul 13:34
50292.5653
6
May 02 12:26
50935.5186
6
Feb 25 10:43
51599.4465
6
2002
Jul 10 11:40
49543.4861
12
23 Aug 10:10
50318.4242
6
Jun 07 21:01
50971.8757
24
23 Mar 04:53 51626.2035
6
Jan 23 12:44
52297.5310
6
Jul 28 07:12
49561.3000
12
18 Sep 16:25
50344.6840
6
Jun 09 23:59
50973.9993
24
Apr 18 19:37
51652.8174
6
Feb 18 22:20
52323.9373
6
Aug 27 09:46
49591.4069
12
18 Oct 07:46
50374.3236
6
Jun 12 08:01
50975.3340
24
May 17 22:08 51681.9225
6
Mar 23 10:22
52356.4321
9
Sep 25 00:46
49620.0319
12
12 Nov 09:40
50399.4031
6
Jun 25 06:59
50989.2910
6
Jun 14 10:27
51709.4354
6
Mar 30 18:02
52363.7516
9
Oct 21 00:41
49646.0285
12
15 Dec 00:00
50432.0417
8
Jun 28 14:06
50992.5881
6
Jul 11 18:12
51736.7583
6
Apr 6 05:34
52370.2321
9
Nov 19 17:29
49675.7285
6
19 Dec 12:33
50436.5229
6
Jul 22 18:56
51016.7889
6
Aug 06 21:43 51762.9049
6
Apr 18 03:03
52382.1271
9
Dec 18 06:00
49704.2500
6
1997
Aug 21 12:23
51046.5161
6
Aug 10 23:58 51766.9992
6
May 17 01:16 52411.0529
6
07 Jan 23:41
50455.9875
6
Sep 15 02:18
51071.0963
6
Sep 7 07:09
51794.2986
6
Jun 12 14:23
6
13 Jan 16:14
49730.6764
6
09 Feb 00:00
50488.0006
6
Oct 14 02:39
51100.1104
6
Oct 4 01:49
51821.0758
6
12 Feb 01:54
49760.0792
6
23 Feb 19:08
50502.7978
6
Nov 10 05:01
51127.2090
6
Oct 6 16:14
51823.6767
6
11 Mar 14:30
49787.6042
6
27 Feb 06:31
50506.2721
6
Dec 08 14:19
51155.5969
6
Nov 2 11:50
51850.4931
6
8 Apr 10:29
49815.4368
6
04 Mar 10:16
50511.4278
6
Dec 31 03:29
51178.1453
6
Nov 8 00:00
7 May 01:13
49844.0507
6
21 Mar 03:35
50528.1494
6
1999
2 Jun 18:30
49870.7708
6
05 Apr 08:50
50543.3681
6
Jan 28 01:06
51206.0458
27 Jun 20:00
49895.8333
6
25 Apr 23:00
50563.9583
6
Feb 23 22:43
30 Jul 08:50
49928.3681
6
15 May 20:18
50583.8460
6
Mar 25 20:15
27 Aug 05:43
49956.2382
6
07 Jun 13:06
50606.5461
6
Apr 20 23:47
51288.9910
6
Feb 20 04:34
51960.1909
6
22 Sep 03:40
49982.1528
6
24 Jun 11:04
50623.4612
6
May 19 08:28
51317.3528
6
Mar 7 05:01
51975.2090
6
17 Oct 09:43
50007.4053
6
24 Jul 18:42
50653.7795
6
Jun 16 07:07
51345.2965
6
Mar 21 12:23 51989.5163
6
15 Nov 08:53
50036.3706
6
20 Aug 02:17
50680.0952
6
Jul 14 04:07
51373.1715
6
Apr 17 22:36
52016.9421
6
14 Dec 07:03
50065.2929
6
17 Sep 17:24
50708.7256
6
Aug 10 04:00
51400.1667
6
May 15 23:23 52044.9744
6
13 Oct 18:00
50734.7506
6
Sep 9 01:27
51430.0604
6
Jun 17 11:04
52077.4614
6
11 Jan 23:24
50093.9750
6
14 Nov 05:19
50766.2217
6
Oct 5 15:27
51456.6437
6
Jul 11 20:19
52101.8466
6
11 Feb 00:30
50124.0208
6
10 Dec 09:40
50792.4027
6
Nov 3 06:51
51485.2854
6
Aug 10 13:15 52131.5526
6
1995
1996
51856.0000
6
Nov 28 18:58 51876.7903
6
6
Dec 30 07:25
51908.3093
6
51232.9471
6
2001
51262.8441
6
Jan 23 17:08
51932.7141
6
52437.5997
9
Proposal ID 8811: WFPC2 Cycle 9 Standard Darks
Plan
Purpose Measure dark current & identify of hot pixels.
Description Six 1800s exp/week with the shutter closed, five with clocks off,
one with clocks on. This frequency is required due to the high
formation rate of new hot pixels (several tens/CCD/day). Five
darks per week are required for cosmic ray rejection, counterbalancing losses due to residual images, & improving the noise
of individual measurements. Sometimes, no usable darks are
available for a given week due to residual images, resulting in a
longer-than-usual gap in the hot pixel lists, but in a decon week,
information on hot pixels that became hot and then annealed
would be lost irretrievably. As a result, pre-decon darks (see
Decon proposal) are executed NON-INT and at least 30 min
after any WFPC2 activity.
Fraction 90%
GO/GTO
Programs
Supported
Resources 366 internal orbits (occultation periods),
Required:
Observation
Products Weekly darks delivered to CDBS and monthly tables of hot pixels on the WWW. Superdark reference files.
Results
Modifications
Execution There were a total of 40 weeks during Cycle 9 for which the
standard darks executed, thus 228 internal orbits (as opposed to
the original 366 requested, or 61 weeks). The initial request contained visits for more than a year to cover contingencies. The
number of weeks was reduced to 40 due to time lost during the
Shutter Anomaly, as well as various scheduling difficulties at
other times during Cycle 9.
In the event of missing darks, additional information on hot pixels was occasionally obtained from the dark frames taken via the
Supplemental Darks program (8443, 8460, 8461). The supplemental darks are not used to generate dark reference files.
Time-line Executed throughout Cycle 9.
Resources 228 internal orbits
Used:
Observation
Products New superdark and dark reference files for pipeline routinely
delivered to CDBS (Wiggs, Mack, & Baggett) and available via
Starview or WWW Reference File listing.
Monthly hot pixel lists are posted to WWW (Wiggs et al.) and
regular updates are made to WFPC2 History File on WWW
(Baggett & Wiggs).
Updates to Instrument Handbook.
10
Plan
Accuracy Require ~1 e-/hr (single-pixel rms) accuracy for most science
Goals applications. Expected accuracy in a typical superdark is 0.05 e/hour for normal pixels. The need for regular darks is driven by
systematic effects, such as dark glow (a spatially and temporally
variable component of dark signal) and hot pixels, which cause
errors that may exceed these limits significantly.
Scheduling& These darks are not run during decon weeks; decon week darks
Special are in decon proposal. As requested, timing requirements have
Requirements been hardcoded with GROUP-WITHIN and BETWEENs.
Results
Accuracy The typical superdark (120 dark frames) accuracy is ~0.07 e-/
Achieved hour. Dark reference files are generated from a superdark plus
hotpixels identified from a weekly (5 dark frames) dark and
delivered for use in the OPUS pipeline. HISTORY keywords in
the dark reference file headers provide details on the generation
of each dark; in addition, ISR 01-01, Creating WFPC2 Dark
Reference files (Mack & Wiggs) provides scripts and instructions for observers who may wish to generate their own pipeline
dark.
As illustrated in Fig. 2, after steadily increasing over the first 5
years, the low-level dark current has now begun to stabilize
(Mack et al., ISR 01-05). The lack of increase in the dark current is presumed due to solar maximum and the associated
decrease in cosmic ray events (a major component of the dark
level stems from CCD window fluorescence due to cosmic
rays). Over the 7 year period, the dark current has increased by a
factor of ~2.0 in the WFC CCDs and by a factor of ~1.3 in PC.
The long-term increase is unlikely to impact adversely the quality of WFPC2 observations (dark current is generally a minor
contributor to the total noise) except perhaps in special cases,
such as faint sources observed in AREA mode through narrowband or UV filters. The changes are included in the pipeline reference files.
Continuation
Plans
11
Figure 2: Dark levels for the central 400x400 pixels in each camera, at gain 7, as a function of time (figure from Mack et al., ISR 01-05) Each data point represents the mean of five 1800 sec dark frames taken just after the monthly decons.
12
Proposal ID 8826-8828: WFPC2 Cycle 9 Supplemental Darks
Plan
Purpose Images will allow for frequent monitoring of hot pixels.
Description This program is designed to provide up to three short (1000s)
darks per day, to be used primarily for the identification of hot
pixels. Shorter darks are used so that the observations can fit
into almost any occultation period, making automatic scheduling feasible. These supplemental darks are low priority, and
should be taken only when there is no other requirement for that
specific occultation period. This program complements the
higher priority Standard Darks proposal that has longer individual observations for producing high-quality pipeline darks and
superdarks. Hot pixels are often a cause of concern for relatively
short science programs, since they can mimic stars or mask key
features of the observations: about 400 new hot pixels/CCD are
formed between executions of the Standard Darks program. The
supplemental darks are available to the GO community from the
archive; there is no plan to use them in our standard analysis and
products.
Fraction 30%
GO/GTO
Programs
Supported
Resources Total of 1282 internal orbits (occultation periods), which allows
Required: for a maximum of 3 darks per day.
Observation
Products None.
Results
Modifications Some darks were not executed as a result of the safing associated with the Shutter Anomaly.
Execution Nominal.
Time-line Executed throughout Cycle 9.
Resources 1254 (450+454+350) internal orbits.
Used:
Observation
Products Archived daily darks are available to GOs via Starview. Very
occasionally, when the standard darks are lost (e.g., due to
scheduling difficulties), some of the daily darks are used to generate the hot pixel lists. However, dark reference files for the
pipeline are always generated from the longer exposure-time
standard darks, never from these shorter daily darks.
13
Plan
Accuracy For archive only, no STScI analysis provided.
Goals
Scheduling& Scheduled at low priority, non-interference basis, maximum of
Special 3/day. Will require multiple proposal IDs due to large number of
Requirements visits (1 dark/visit to maximize scheduling flexibility).
Results
Accuracy The daily darks are archived only.
Achieved Some of these daily darks (as well as some standard darks) were
used to follow-up on a study of charge trapping as measured in
residual images found in darks (Baggett et al., ISR 00-03); Fig.
5 illustrates the effect. The new data support the original finding
that the amount of charge trapped appears correlated with the
maximum intensity clocked through the pixel during readout
(Biretta & Mutchler, ISR 97-05). Furthermore, the amount of
charge seen in the residual images appears to have been stable
over the six years, in marked contrast to the evolving CTI
(charge transfer inefficiency) found via photometry of external
stellar images (e.g., Whitmore et al., 1999) and analysis of cosmic ray tails in dark frames (Riess et al., ISR 99-04). Finally,
evidence was found that these residuals can be relatively longlived: some residuals appeared in darks started more than 20
minutes after the external image was read out.
Continuation
Plans
14
Proposal ID 8812: WFPC2 Cycle 9 Internal Monitor
Plan
Purpose Verify the short-term instrument stability at both gain settings
and provide INTFLATs for calibrating preflashed observations.
Description Each set of internal observations consists of 8 biases (4 at each
gain) and 4 INTFLATs (2 at each gain). The entire set should be
run once per week, except for decon weeks, on a non-interference basis. During the decon week, INTFLATs in F502N will be
taken, with each shutterblade and at a variety of exposure times
to test for linearity. The F502N filter is likely to be the recommended filter for preflashing observations.
Fraction 100%
GO/GTO
Programs
Supported
Resources 76 internal orbits (occultation periods); 46 will be needed for the
Required: usual monitor while 30 will be required for the new F502N
Observation intflat monitoring.
Results
Modifications Some visits were not scheduled as a result of time lost due to the
Shutter Anomaly.
Execution Nominal.
Time-line Executed throughout Cycle 9.
Resources 68 internal orbits
Used:
Observation
Products Superbiases delivered annually to CDBS; TIPS reports on possible buildup of contaminants on the CCD windows (worms) as
well as gain ratio stability, based on INTFLATs. A Technical
Instrument Report will be issued if significant changes occur.
Possible preflash correction images will be generated.
Products Updated bias files have been installed in CDBS (Gonzaga et al.)
and are accessible via Starview or WWW Reference File listing.
Some data are also being used in a long-term study Gonzaga et
al. (in progress). Updates have also been included in the WFPC2
Instrument Handbook.
Accuracy Approximately 120 bias frames are used for each superbias
Goals pipeline reference file, generated once a year; accuracy is
required to be better than 1.5 e-/pixel, and is expected to be 0.8
e-/pixel.
Accuracy No significant differences were found between the old and new
Achieved biases. Statistics for these files are listed in Table 3.
The intflat analyses have found small (few tenths of a percent)
changes in the intflat lamp brightness across cycle 8, well within
the gradual long-term trends (see Fig. 6). There are also small
changes in the illumination patterns: ratios of intflats taken from
mid-99 to 2001 show small amplitude (0.1 - 1%) large scale
variations which are chip and wavelength dependent. The four
Carley bulbs may not be varying in the same manner, which
would induce the observed changes in the illumination pattern
of the intflats. The variation in the lamp brightness may be associated with changes in temperature.
15
Plan
Results
Scheduling& Regular internals to be scheduled on non-decon weeks, F502N
Special INTFLATs during decon weeks though they are not linked to
Requirements the decon itself. As requested, timing requirements have been
hardcoded with GROUP-WITHIN and BETWEENs.
Continuation
Plans
Table 3: Statistics (in DN) of superbias files delivered to CDBS (Gonzaga, Platais et al.); pedigree column lists epoch of bias frames used in the superbias.
In each case, the statistics include all the pixels across each chip, excluding only the bad pixels flagged in the data quality file associated with each reference
file.
PC
WF2
WF3
WF4
pedigree
name
gain
of superbias reference file
mean stddev mean stddev mean stddev mean stddev dates of bias frames used to generate reference files
i2i1201qu
7
0.343 0.128
0.313 0.154
0.295 0.134
0.318 0.146
31/07/1996-30/11/1997
i9817383u
7
0.347 0.149
0.327 0.254
0.314 0.494
0.344 0.306
01/12/1997-13/08/1998
j9a1612mu
7
0.345 0.141
0.336 0.267
0.330 0.533
0.351 0.388
29/08/1998-21/08/1999
kcd1557lu
7
0.350 0.139
0.335 0.188
0.326 0.523
0.342 0.278
26/08/1999 - 29/08/2000
l9i12088u
7
0.348 0.197
0.344 0.400
0.327 0.597
0.351 0.447
09/06/2000 - 27/08/2001
i2h1025iu
15
0.176 0.075
0.160 0.085
0.149 0.079
0.169 0.090
22/08/1996-30/11/1997
j3f1747qu
15
0.183 0.084
0.163 0.131
0.168 0.087
0.185 0.161
01/12/1997-13/08/1998
j9a1612nu
15
0.188 0.081
0.162 0.137
0.154 0.267
0.181 0.205
29/08/1998-21/08/1999
kci1424gu
15
0.183 0.080
0.172 0.101
0.159 0.266
0.169 0.146
26/08/1999 - 29/08/2000
l9i12087u
15
0.186 0.108
0.185 0.203
0.177 0.340
0.196 0.232
09/06/2000 - 27/08/2001
16
Figure 3: Observed counts in the inner 300x300 pixels of the F555W intflats as a function of Modified Julian Date, one plot per camera. Open and closed
circles are for gains 15 and 7, respectively; Servicing Missions are marked with short vertical lines. Plots were generated from MEANC300 header keyword
values, after subtracting an average bias level (DEZERO keyword); figure is from Gonzaga et al. (in prep).
17
Proposal ID 8815: WFPC2 Cycle 9 Earth Flats
Plan
Results
Modifications
Purpose Monitor flatfield stability. This proposal obtains sequences of
Earth streak flats to construct high quality flat fields for the
WFPC2 filter set. These flat fields will allow mapping of the
OTA illumination pattern and will be used in conjunction with
previous internal and external flats to generate new pipeline
superflats. These Earth flats will complement the Earth flat data
obtained during SMOV and Cycles 4-8.
Description Observations of the bright Earth (earthcals) are obtained in a
variety of filters. Approximately 200 exposures in each of four
narrowband filters (F375N, F502N, F656N, F953N) are
required, as well as about 50 exposures in other filters
(F160BW, F336W, F343N, F390N, F437N, F469N, F487N,
F631N, F658N, F673N -- the F160BW filter is included to provide pinhole information). In addition, if dark-earth pointing
becomes available, some of the broadband filters are requested
(F336W, F439W, F555W, F675W, and F814W; all marked as
on-hold for now), 10 exposures in each filter.
Fraction 100%
GO/GTO
Programs
Supported
Resources 210 internal orbits (occultation periods).
Required:
Observation
Execution An additional 14 internal orbits were used, taking the total to
224, in order to fill in the gap in execution until the start of the
Cycle 10 Earthflat programs, at the end of Cycle 9.
Time-line Executed throughout Cycle 9.
Resources 224 occultation periods.
Used:
Observation
Products New flatfields generated and delivered to CDBS if changes
detected.
Products Reference file generation and delivery planned for end of 2001.
Results also presented at TIPS and AAS (Koekemoer et al.)
Accuracy The single-pixel signal-to-noise ratio expected in the flatfield is
Goals 0.3%.
Accuracy Comparison of Earth flats from the last few Cycles reveals that
Achieved most of the field-of-view shows little change (<0.3%). The largest changes are near the CCD corners, likely due to long-term
changes in the geometry (Koekemoer et al.)
Scheduling& None.
Special
Requirements
Continuation
Plans
18
Proposal ID 8816: WFPC2 Cycle 9 UV Earth Flats
Plan
Results
Modifications
Purpose Monitor flatfield stability. This proposal obtains sequences of
earth streak flats to improve the quality of pipeline flat fields for
the WFPC2 UV filter set. These Earth flats will complement the
UV earth flat data obtained during Cycle 8.
Description Earth streak-flats are taken in UV filters (F170W, F185W,
F218W, F255W, F300W, F336W, and F343N). Those UV filters
with significant redleak will also be observed crossed with
selected broadband filters (F450W, F606W, F675W, and
F814W), in order to assess and remove the redleak contribution.
Earthflats required: 100 for each of the 7 UV filters plus 20 with
each of the crossed filter sets (16 combinations). The entire proposal should be done within 7 months, with the observations
evenly distributed over that period of time. The observations are
divided into 10 batches, with each batch done 21 days apart.
Fraction ~10%
GO/GTO
Programs
Supported
Resources 400 occultation periods.
Required:
Observation
Execution The proposal contained additional contingency internal visits,
not all of which executed in Cycle 9 due to scheduling constraints. These are carried over into the Cycle 10 UV Earthflat
calibration program.
Time-line Executed throughout Cycle 9.
Resources 306 occultation periods.
Used:
Observation
Products Updated flatfields for pipeline via CDBS.
Products High S/N UV flat field files generated by Karkoschka & Biretta
2001 (ISR-01-07) as an outsourcing program.
Accuracy 3-10%. Outsourcing candidate.
Goals
Accuracy For the UV flatfields, the accuracy achieved was about 0.6-0.7%
Achieved rms, which was an improvement over the previous levels of
around 2% in the UV flats.
Scheduling& None.
Special
Requirements
Continuation
Plans
19
Figure 4: Comparison between the effects of original pipeline UV flatfields, and the higher S/N UV flats created by Karkoschka and Biretta (ISR 01-07).
20
Proposal ID 8813: WFPC2 Cycle 9 Astrometric Monitor
Plan
Purpose Verify relative positions of WFPC2 chips with respect to one
another.
Description The positions of the WFPC2 chips with respect to each other
appear to be shifting slowly (by about 1 pixel, since 1994). The
rich field in w Cen (same positions as cycle 8 proposal 7627) is
observed with large shifts (35’’) in F555W only, every ~six
months. This will allow monitoring of shifts in the relative positions of the chips or changes in the astrometric solution at the
sub-pixel level. Kelsall spot images will be taken in conjunction
with each execution.
Fraction <20%. Also supports WFPC2-assisted target acquisitions for
GO/GTO other instruments.
Programs
Supported
Resources 2 pointed orbits and 2 occultation periods need for this program,
Required: each separated by 6 months.
Observation
Results
Modifications
Execution Nominal.
Time-line Executed 18 July 2000, and 17 Feb 2001.
Resources 2 external orbits.
Used:
Observation
Products Products: TIPS reports, ISR, update of chip positions in PDB
and of geometric solution in STSDAS tasks metric and wmosaic
if significant changes are found.
Products Data were combined with those from previous Cycles to carry
out a self-consistent solution for all the chips (Casertano &
Wiggs 2001, ISR-01-10); see Fig. 5.
Accuracy At least 0.01’’ in relative shifts; 0.05” or better for absolute.
Goals
Accuracy 0.0012” in the WF cameras, and 0.003” in the PC.
Achieved
Scheduling& None.
Special
Requirements
Continuation
Plans
21
Figure 5: Modified Holtzman solution (left), compared with the new solution derived by solving simultaneously for all four CCDs in a self-consistent solution
(Casertano and Wiggs, ISR 01-10).
22
Proposal ID 8817: WFPC2 Cycle 9 Intflat Sweeps and Linearity Test
Plan
Results
Purpose Using INTFLAT observations, this WFPC2 proposal is designed Modifications
to monitor the pixel to pixel flatfield response and provide a linearity check. The INTFLAT sequences, to be done once during
the year, are similar to those from the Cycle 8 program 8448.
The images will provide a backup database in the event of complete failure of the VISFLAT lamp as well as allow monitoring
of the gain ratios. The sweep is a complete set of internal flats,
cycling through both shutter blades and both gains. The linearity
test consists of a series of INTFLATs in F555W, in each gain
and each shutter.
Description Intflat sweep - flatfields are obtained with a variety of filters
(F336W, F439W, F547M, F555W, F569W, F606W, F622W,
F631N, F502N, F656N, F675W, F673N, F702W, F785LP,
F814W, F1042M) using shutters A and B, and gains 7 and 15;
the BLADE optional parameter is used throughout. A smaller
set is obtained only at gain 7 using any shutter blade (F160BW,
F300W, F380W, F390N, F410M, F437N, F450W, F469N,
F487N, F467M, F588N, F658N, F791W, F850LP, F953N).
Execution Nominal.
Linearity test - flatfields are taken with F555W at a variety of
exposure times, using shutters A & B, and gains 7 & 15. In addition, a set is done with clocks=YES (only gain 7, shutter A; gain
7 shutter B set was taken during Cycle 8). Since the INTFLATs
have significant spatial structure, any non-linearity should
appear as a non-uniform ratio of INTFLATs with different exposure times.
Fraction 100%
GO/GTO
Programs
Supported
Resources 21 internal orbits (occultation periods)
Required:
Observation
Time-line Executed from Mar 9, 2001, to Mar 20, 2001.
Resources 21 internal orbits.
Used:
Observation
23
Plan
Results
Products TIPS, TIR if any significant variations are observed.
Products Analysis of long-term trends in the intflats, visflats, and uvflats
is in progress (Gonzaga et al.); an anomaly in the FR533N filter
rotation found during that study has already been reported
(Gonzaga et al., ISR 01-04).
Accuracy INTFLATs: Stable to better than 1%. (INTFLATs will provide a
Goals baseline comparison of INTFLAT vs VISFLAT (taken in decon
proposal) if the CAL channel system fails.)
Accuracy Gain ratios as measured from FR533N visflats are stable to betAchieved ter than 1% (Gonzaga et al., ISR 01-04). The apparent gain
quantization seen in the early data is not real but an artifact of an
apparently randomly occurring rotational offset in the filter
wheel positioning of about 0.5 degrees in some images (corresponding to one filter step). The pivot point of the rotation
implicates the filter wheel as the source of the inconsistency.
The photometric effect of the FR533N filter anomaly has been
estimated at less than 1% (Gonzaga et al., ISR 01-04). A cursory
check of several filters on other filter wheels shows no similar
problem. At this time, the source of this problem (mechanical or
software) is unknown.
Scheduling& Intflat sweeps should be scheduled within a 2-week period. To
Special minimize filter wheel usage, each filter will be cycled through
Requirements the two shutters and two gains. Each visit will contain just a few
filters, in order to allow flexibility in scheduling, however, the
sweep INTFLATs should be done over as short a time period as
possible (2 weeks) and in the same month as the VISFLATs
(~March/ early April 2001). VISFLATs, as well as the small
monthly INTFLAT sets (5 broadband filters), which must be
tied to a decon, will be included in the Cycle 9 decon proposals.
Upon request, to facilitate implementation and scheduling, these
timing requirements are hardcoded as the specified GROUPWITHIN and BETWEEN special requirements.
Continuation To minimize the lamp degradation, the number of visflats taken
Plans was dramatically reduced after Nov 1996 (MJD=50400).
24
Proposal ID 8818: WFPC2 Cycle 9 Photometric Characterization
Plan
Purpose Provide a check of the zeropoints and contamination rates in
non-standard WFPC2 filters.
Description Observations of the standard star GRW+70D5824 in PC1 and
WF3 will be made using filters that are not routinely monitored
(F380W, F410M, F450W, F467M, F547M, F569W, F606W,
F622W, F702W, F785LP, F791W, F850LP, and F1042M).
Images should be taken within 7 days after a decon, to minimize
any contamination effects. Results from this program will be
compared with data from the cycle 7 program 7628 and cycle 8
program 8451.
Fraction 100%
GO/GTO
Programs
Supported
Resources 2 orbits.
Required:
Observation
Results
Modifications
Execution Nominal.
Time-line Executed Mar 24, 2001.
Resources 2 external orbits
Used:
Observation
Products TIR, SYNPHOT update if necessary.
Products Analysis in progress (Heyer, Whitmore et al.)
Accuracy 2% photometry.
Goals
Accuracy
Achieved
Scheduling& Execute within 7 days of decon. Upon request, to facilitate
Special implementation and scheduling, these timing requirements are
Requirements hardcoded as the specified GROUP-WITHIN and BETWEEN
special requirements.
Continuation
Plans
25
Proposal ID 8819: WFPC2 Cycle 9 PSF Characterization
Plan
Results
Purpose Provide a subsampled PSF over the full WFPC2 field of view in Modifications
order to support PSF fitting photometry and provide data to test
PSF subtraction as well as dithering techniques (e.g., effects of
OTA breathing and gain).
Description Measure PSF over full field in photometric filters in order to
update the TIM and TINYTIM models and to allow accurate
empirical PSFs to be derived for PSF fitting photometry. These
observations will also be useful in order to test PSF subtraction
and dithering techniques at various locations on the CCD chips.
With ~1 orbit per photometric filter, each star is measured 16
times per filter at different pixel phase, providing a high S/N,
critically sampled PSF. This will improve the quality of PSF fitting photometry. The step size is 0.125 arcseconds, very close to
1.25 pixels in the WFs and 2.75 pixels in the PC - so that fractional steps of 0.25, 0.5, and 0.75 pixels are used in each camera. This provides a critically sampled PSF over most of the
visible range. The crowded w Cen field is used, with 40 sec
(gain = 15) images taken through each of the wide standard photometric filters (F336W, F439W, F555W, F675W and F814W).
The Cycle 9 observations use the same pointings as in Cycles 7
and 8. The proposal also allows a check for subpixel phase
effects on the integrated photometry.
Fraction 15%
GO/GTO
Programs
Supported
Resources 6 pointed orbits. This is slightly higher than last time (5 orbits)
Required: due to removal of scan capability.
Observation
Products PSF library (WWW). Updates for TIM and TINYTIM. Accurate empirical PSFs to be derived for PSF fitting photometry.
Execution Nominal.
Time-line Executed Jun 04, 2001.
Resources 6 external orbits.
Used:
Observation
Products Images are available via Starview and in the process of being
archived into the WWW PSF library.
26
Plan
Accuracy If breathing is less than 5 microns peak to peak, the resulting
Goals PSFs should be good to about 10% in each pixel. PSF fitting
results using this calibration would of course be much more
accurate. In addition, the test gives a direct measurement of subpixel phase effects on photometry, which should be measured to
better than 1%.
Scheduling& Same pointing and orientation as Cycle 7 observations for proSpecial posal 7629 and Cycle 8 proposal 8451. Visits should be comRequirements pleted within 2 week timeframe to minimize spacecraft
temperature differences.
Results
Accuracy
Achieved
Continuation
Plans
27
Proposal ID 8814: WFPC2 Cycle 9 Redleak Check
Plan
Results
Purpose Obtain an on-orbit verification of the red leak in WFPC2 UV fil- Modifications
ters by observing solar analog standards in the UV.
Description Two targets, for which FOS spectrophotometry is available, will
be chosen from those used in the solar analog photometric verification program (P041-C, P177-D, or P330-E; Cycle 6 proposal
6934 and 6179). Observed countrates will be compared to SYNPHOT predictions of the expected count rates from the UV
proper and from the red leak. A robust verification of the red
leak will benefit programs that rely on precision multicolor photometry and comparison with model spectra. Some discrepancies seen thus far could be explained by a significant (> 10%)
error in the estimated red leak.
Fraction ~10%
GO/GTO
Programs
Supported
Resources 3 orbits, one per target.
Required:
Observation
Execution No anomalies.
Time-line Executed Oct 8, 2000; Dec 4, 2000; and Jan 2, 2001.
Resources 3 external orbits.
Used:
Observation
Products TIR and SYNPHOT update if necessary.
Products In progress.
Accuracy 2% on the flux measurements; accuracy of redleak determinaGoals tion will vary by filter.
Accuracy Analysis in progress (Baggett et al.)
Achieved
Scheduling& None.
Special
Requirements
Continuation
Plans
28
Proposal ID 8821: WFPC2 Cycle 9 CTE - Monitor and Absolute Calibration
Plan
Purpose Monitor CTE changes during Cycle 9 and provide complementary suite of observations to groundbased CTE proposal.
Description Monitor: Observations of w Cen (NGC 5139) are taken every 6
months during cycle 9 to monitor changes in the CTE (charge
transfer efficiency) of WFPC2. An extension of proposals 7629
and 8447, the principal observations will be at gain 7, in F814W
and F555W, in WF2 and WF4, at a variety of preflash (background) levels (20 to 1000 electrons).
Results
Modifications
Execution Nominal.
Absolute Calibration: Observations of three of the globular clusters Eridanus, NGC 2419, Pal 3, Pal 4, and Pal 14 are planned,
to match the targets selected for a companion ground-based proposal - subject to approval of the latter. Direct comparison with
ground-based observations permits a direct verification of the
absolute photometric calibration of WFPC2 in observations that
may be affected by CTE, and therefore a more robust determination of the zero point for many WFPC2 observations. While
there is no evidence that the current WFPC2 zero point is inapplicable to faint sources, enough corrections need to be applied
that a direct verification is extremely desirable. Comparison to a
well-populated field observed from the ground can also yield a
direct, independent determination of the CTE effect in such
observations (Stetson 1998). Five suitable fields with existing
WFPC2 observations have been selected (w Cen and a WIYN
3.5m proposal (PI Whitmore) has been submitted for groundbased observations of these fields with exposure times sufficient
to reach 1% photometric accuracy at V=22. The ground-based
proposal asks for observations of three of these five fields, to be
chosen on the basis of their RA and the time of the observations.
Fraction 30 - 50%
GO/GTO
Programs
Supported
Time-line Executed on 6 different dates throughout Cycle 9.
29
Plan
Resources 15 external orbits total. Six for w Cen (3 per execution, done
Required: twice during cycle) plus 9 orbits for the followup to ground
Observation based observations (3 orbits per target, 3 targets).
Results
Resources 15 external orbits
Used:
Observation
Products Instrument Science Report. Outsourcing candidate?
Products ISR published (Heyer 2001, ISR-01-09), see Fig. 6; results
incorporated into the WFPC2 Instrument Handbook as well as
presented in posters at AAS meetings, in WFPC2 STANs (electronic Space Telescope Analysis Newsletter), and in the. CTE
Estimation tool on the WWW.
Accuracy 0.01 magnitudes.
Goals
Accuracy The monitor observations indicate that for very faint stars on a
Achieved very faint background, the CTE loss from the top to the bottom
of the chip has increased from about 3% shortly after the
cooldown of WFPC2 (April 1994) to over 50% in 2001 (see Fig.
6). In general, typical WFPC2 exposures are much longer than
these short calibration images, resulting in higher background
which significantly reduces the CTE loss and minimizes the
CTE problem for most science exposures. Observers interested
in minimizing CTE losses should consider placing their targets
near the readout amplifier (low X,Y), applying corrections after
their observations, possibly preflashing in certain situations, and
avoiding very short exposures (i.e., low background).
Scheduling& For each monitoring visit, observations will be done in single
Special guide star mode.
Requirements
Continuation
Plans
30
Figure 6: Change in CTE losses, from 1994 to 2001, for a range of target brightnesses, background levels, and filters (Heyer et al. 2001, ISR-01-09).
31
Proposal ID 8820: WFPC2 Cycle 9 Wavelength Stability of Narrowband and Linear Ramp Filters
Plan
Results
Purpose Verify the mapping of wavelength as a function of CCD position Modifications
on LRFs; check for changes in central wavelengths of narrow
band filters.
Description On-orbit VISFLATs taken through the ramps crossed with the
narrow band filters will constrain the wavelength calibration of
the ramps filters relative to the narrow band filters. Comparison
with similar Cycle 4 data will show whether the filter properties
have evolved with time due to annealing / shrinkage of the thin
film materials. The uncrossed VISFLATs can also be used to
constrain the transverse (cross-wavelength) placement of the
ramp filters.
Execution Nominal.
In addition, 4 external orbits are required for external observations of an extended line emission source (planetary nebula)
through ramp filters. These will provide an absolute test for
changes in the ramp filters.
Fraction 11%
GO/GTO
Programs
Supported
Resources 4 external orbits and 15 internal orbits (12 for Earth flats and 3
Required: for VISFLATs).
Observation
Time-line Executed throughout Cycle 9.
Resources 4 external and 15 internal orbits.
Used:
Observation
Products New aperture locations if necessary. Updated wavelengths /
throughput curves for both ramp and narrow band filters in
SYNPHOT.
Products In progress (Biretta et al., in prep.).
Accuracy Central wavelengths to 2Å.
Goals
Accuracy Analysis is in progress. Initial results (McMaster & Biretta,
Achieved priv.comm.) have shown ~1% agreement between the groundbased calibration and the on-orbit data, though there remains a
5-10% RMS scatter between individual data points (the latter is
still under investigation).
Scheduling& Number of VISFLAT lamp cycles must be minimized, to reduce
Special amount of lamp throughput degradation.
Requirements
Continuation
Plans
32
Instrument Science Report WFPC2 2003-01
References
General Documents
Site Map of WFPC2 WWW pages
WFPC2 Advisories
WFPC2 Documentation
WFPC2 Software Tools
WFPC2 User Support
Frequently Asked Questions
WFPC2 Clearinghouse
The WFPC2 Instrument Handbook
The Dither Handbook
The HST Data Handbook
STAN, the Space Telescope Analysis Newsletter
Proposals in Phase II format, page maintained by PRESTO
WFPC2 PSF page
Workshop on Hubble Space Telescope CCD Detector CTE, Jan. 2000
New ISRs and other reports covered in the present report.
01-10: An Improved Geometric Solution for WFPC2, Casertano & Wiggs.
01-09: The WFPC2 Photometric CTE Monitor, Heyer.
01-08: Creating WFPC2 Dark Reference Files: ADdendum, Mack, Biretta, Baggett, &
Proffitt.
01-07: WFPC2 Flatfields with Reduced Noise, Karkoschka & Biretta.
01-06: WFPC2 Cycle 8 Closure Report, Baggett, Gonzaga, Biretta, Casertano, Heyer,
Koekemoer, Mack, McMaster, Riess, Schultz, Wiggs.
01-05: WFPC2 Dark Current vs. Time, Mack, Biretta, Baggett, & Proffitt.
01-04: Preliminary Assessment of the FR533N Filter Anomaly, Gonzaga, Baggett, Biretta
01-03: WFPC2 Cycle 10 Calibration Plan, Baggett, Gonzaga, Biretta, Heyer, Koekemoer,
Mack, McMaster, Schultz.
00-04: How CTE Affects Extended Sources, Riess.
00-01: WFPC2 Cycle 9 Calibration Plan, Baggett, Gonzaga, Biretta, Casertano, Heyer,
Koekemoer, McMaster, O’Dea, Riess, Schultz, Whitmore, & Wiggs.
99-04: Time Dependence of CTE from Cosmic Ray Trails, Riess, Biretta, Casertano.
Charge-Transfer Efficiency of WFPC2, PASP 11,1559, Dec 1999, Whitmore, Heyer, &
Casertano.
Internal reports
01-02 Testing On-The-Fly-Reprocessing with WFPC2, Gonzaga, Baggett, & Biretta.
01-01 Shutter Jitter History Measured from INTFLATs, Riess, Casertano, & Biretta.
For paper copies of any documents listed here, please contact help@stsci.edu.
33