n
Wide Field Planetary Camera II Status Update
I. Heyer, J. Biretta, S. Baggett, S. Casertano, S. Gonzaga, A. Koekemoer, J. Mack, M. McMaster, A. Riess, A. Schultz (STScI)
Instrument Handbook Update.
Abstract
WFPC2’s
100,000th
on-orbit image.
Here’s what’s new in Version 6.0 for Cycle 11:
We review the status of the Wide Field and Planetary Camera II (WFPC2) onboard the Hubble
Space Telescope, as well as recent enhancements
to calibration and user support. The instrument
recently passed the 100,000 image mark and continues to perform well. Long-term issues with
Charge Transfer Efficiency (CTE) in the CCDs
(see separate poster) are an on-going concern, but
impact only a minority of the current science
observations. The photometric, flat field, and PSF
stabilities continue to be excellent. The Cycle 9
calibration program is well underway and closely
follows calibrations from previous cycles. Three
new programs have been implemented as well: a
red leak check, a verification of the wavelength
stability of the narrowband and linear ramp filters,
and an absolute calibration of CTE losses. New
plans for Cycle 10 calibration are discussed. The
"On the Fly Calibration" system has been highly
successful, and continues to supply HST archive
users with images with the most up-to-date calibrations; we discuss the recent "On The Fly
Reprocessing" upgrade. The WFPC2 Instrument
Handbook is being updated for Cycle 11; we
expect only minor revisions which are summarized. The recent "Dither Handbook" discusses
strategies for pointing dithers during observations,
as well as data reduction using the "Drizzle" software. These and other recent works will be highlighted.
•Anomalies: Added information on the shutter anomaly,
the ORIENT bug, and the FR533N anomaly.
•Dark Current Evolution: New information on the latest
results.
•Dithering: Updated information on dithering from the
new Dithering Handbook.
•CTE: Updated CTE monitor figure to reflect the latest
results. Added section on mitigating CTE effects.
•Photometry: Updated photometry monitor.
•Calibration: Added sections on the "On The Fly Reprocessing System" and the "Cycle 10 Calibration Plan."
•Updated references and index.
This Handbook will appear on the WFPC2 WWW
pages accessible at http://www.stsci.edu/ftp/
instrument_news/WFPC2/wfpc2_top.html .
This image of ESO510-13
was taken on April 7, 2001.
A full color image will be
released in early July.
Photometric Monitor. The standard
Dither Handbook. We have
star GRW+70D5824 is regularly observed to monitor photometric throughput. These observations,
conducted since May 1994, indicate that the
throughput for most filters has been stable to ~2%.
However, the far-UV throughput in the PC appears
to be increasing with time. This effect, seen in
F160BW and F170W filter plots, is probably due
to the slow outgassing of some contaminants.
Note: the bi-modal appearance of the UV filters is
due to the decontamination procedure, where the
WFPC2 is warmed to approximately 20 degrees
Celsius for 6-12 hours to remove the build-up of
contaminants. High points indicate high-throughput measurements taken after decontamination.
released "The Dither Handbook"
(Koekemoer, et al., 2000), a complete
guide to planning, obtaining and analyzing dithered HST data. This document
provides general discussions on dithering
strategies with HST instruments (currently including WFPC2, STIS, and
NICMOS, and in the future ACS),
together with a "Cookbook" section that
gives detailed examples of drizzling procedures. All the input images and scripts
for these examples, as well as the final
output images, are available from our
WFPC2 website, to enable observers to
gain experience in the use of the drizzling software through practicing with
these examples. Complete information
and software can be found at:
http://www.stsci.edu/instruments/wfpc2/
dither.html.
Dark Current vs. Time. This plot
Cycle 10 Calibration Plan. As in previous cycles, the Cycle 10 calibration program is aimed at
maintaining the calibration of WFPC2 via the internal and external monitoring programs as well as performing
several new tests. The standard suite of calibrations will be continued, including those used to monitor the health of
the instrument as well as the programs to collect data for calibration reference files. In addition, several new proposals will be implemented: a measurement of the effect of CTE on astrometry, a characterization of the PSF
wings, a calibration check of the clocks ON mode, and a test of the methane quad filter throughput. The plan does
not include any calibrations associated with the next servicing mission (SM 3b), currently scheduled for January
2002. The full calibration plan is in ISR WFPC2 2001-03.
WFPC2 Instrument
Science Reports. Several
new ISRs have been published:
•2001-01 “Creating WFPC2 Dark
Reference Files“, Mack and Wiggs.
•2001-02 “Noiseless Preflashing of
the WFPC2 CCDs“, Schultz, Heyer,
Table 1: WFPC2 Cycle 10 Calibration Plan
ID
Proposal Title
and Biretta.
Estimated Time
(orbits)
Frequency
“External” “Internal”
89328934
WFPC2 Decons &
Associated
Observations
1-2/4 wks
Scheduling
Required
Products
Routine Monitoring Programs
19 phomon 82
every 28 d
CDBS, IHB,
1-2%
2 UV thru.put
Synphot,
2 UV flats
WWW reports
8935
Standard Darks
weekly
318
every 7 d
88368838
8839
Supplemental Darks
0-3/day
1095
every day
Internal Monitor
weekly
76
every 7 d
CDBS
8840
8841
8842
Earth Flats
continuous
UV Earth Flats
continuous
Intflat & Visflat Sweeps 1/cycle
210
400
61
mid to late
early to mid
mid-cycle
CDBS
CDBS
TIR
9253
9254
9251
9255
9257
9252
9256
Astrometric Monitor
2/cycle
CTE Photometric Mon- 2 x 3 orbits
itor
Photometric Character- 1
ization
Astrometric Effects of
CTE
Super-PSF
CDBS
Special Calibration Programs - Continuations
2
2
early & late ISR, STSDAS
6
mid & late
ISR
4
1
12
1
6
Clocks ON Verification 1
Methane Quad Filter
1
Check
1
1
~10% reserve
6
TOTAL TIME (including all executions)
Accuracy
Required
mid-cycle
ISR, Synphot
Special Calibration Programs - New
late
ISR
mid-cycle
50
61
early
mid-cycle
2294
CDBS, STSDAS, ISR
ISR, Synphot
Synphot, ISR
1 e-/hr
n/a
0.8e-/pix
0.3%
3-10%
0.3%
0.05’’
0.01 mag
2-3%
Notes
•2001-03 “WFPC2 Cycle 10 Calibration Plan“, Baggett, Gonzaga,
Decons, phot. & focus
monitor, internals, UV
throughput, visflats and
uvflats.
Also for WWW hot pixel lists.
For archive only, no analysis.
Incl. intflats for preflash.
Outsourcing candidate.
Incl. filter rotation offset
check.
ω Cen as well as K-spots.
Continuation of monitors.
Biretta, Heyer, Koekemoer, Mack,
Target kept on 1 chip.
10%
PSF wing characterization.
2-3%
5%
Closure calibration.
Test of transmission curve
across aperture (GO suggestion). Outsourcing candidate.
Placeholder for unexpected
items.
OTFR - On The Fly Reprocessing - Released May 16, 2001.
Introduction to OTFC (On the Fly Calibration)
•Until a year ago, data were calibrated as they were received at STScI. Results were stored in the HST archive (DADS), and could be
retrieved via Starview from DADS.
•OTFC calibrates data as it is requested by users from the HST archive, using latest calibration software, files, and recommended
parameter values.
•CADC/ST-ECF developed an OTFC system (Crabtree, et al., 1996). OTFC at STScI requires high throughput capability and integration with existing data processing systems. In addition, it provides improved values to parameters (keywords) in archived datasets as
they are determined by the instrument groups.
Impact to Users --> NONE
McMaster, and Schultz.
OTFC switch to OTFR
•2001-04 “Preliminary Assessment
Time“, Mack, Biretta, Baggett, and
•Changes are transparent to HST archive users.
•Requests for data are submitted as usual (Starview or WWW); calibrated data delivered.
•All requests for WFPC2 data will be handled by the OTFR system, no exceptions.
•OTFC processing started with raw files and performed only calibration.
•OTFR processing will start with the original telemetry files (“POD” files) received at STScI from Goddard and run the entire pipeline
(OPUS & calibration). See Table 1 below.
•OPUS processing steps will have fixed the majority of keyword problems automatically (i.e., significantly fewer header fixups
required in OTFR)
Proffitt.
NOTE: Do not run UCHCOORD (version prior to May 2001) on OTFR data.
of the FR533N Filter Anomaly“,
Gonzaga, Baggett, and Biretta.
•2001-05 “WFPC2 Dark Current vs.
The ISRs can be accessed on the web
at http://www.stsci.edu/instruments/
wfpc2/wfpc2_bib.html
All four chips.
1-2 mas
shows the dark current for the central 400x400 pixel
region of WF3 (the other chips show similar results).
Note the levelling off after MJD 51200 due to solar
maximum and reduced cosmic ray flux. The full
details can be found in ISR WFPC2 2001-05.
References to published results of
the data discussed in this poster are
available in a handout. We have
limited copies available of the
Dither Handbook, the WFPC2
Handbook, and several of the latest
ISRs underneath this poster. If you
don’t find what you need please
either check our website, or leave
your name, address, and list the
document(s) you’d like mailed.
Table 1: Benefits of On-The-Fly Systems
OTFC
OTFR
Improved calibration files are used by calwp2.
Same as OTFC.
Most recent calibration software is used, allowing for improved algorithms, new capabilities, and software fixes.
Same as OTFC. In addition, the most recent OPUS pipeline software is
used (pre-calwp2 processing steps of data partitioning, data editing, and
generic conversion).
Header keywords can be corrected if needed.
Same as OTFC. Extra benefit: significantly fewer fixups will be
required in OTFR than in OTFC.
Only uncalibrated data need be stored in the archive.
No calibrated or uncalibrated data need be stored in the archive. Only
the “POD” file (original telemetry data received at STScI from Goddard) is required for OTFR.
Raw files are retrieved from the HST archive and passed to the OTFC
system. For WFPC2, the raw files include d0, q0, q1, x0, and trl files.
POD file (original telemetry file) is retrieved from HST archive and
passed to OTFR system. For WFPC2, there is typically 1 POD file for
each image. OPUS processing is performed: data partitioning, data
editing, and generic conversion (generation of raw files).
References
http://www.stsci.edu
http://archive.stsci.edu
http://www.dpt.stsci.edu/otfc/external/otfc_index.html