STIS Cycle-17 Calibration Phase-1 Template
Last Revised: February 19, 2009
Proposal ID: 11843
Title: CCD Performance Monitor
PI: Michael A. Wolfe
Co-I(s): Rachel Osten
Charles Proffitt
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# Orbit estimates are TOTAL for all of cycle-17; assume 4 weeks
# 01 September 2009, 01 March 2010, 01 September 2010
Total Prime Orbits: 0
External Parallel Orbits: 0
Internals or no-impact orbits: used 24 allowed 27
Comments on orbit estimate: Orbits will occur every six months
starting in September 2009, March 2009, then September 2010.
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# This section should be written with a GO audience in mind -- use
# Calibration plans in WFPC-2 handbook as a guide.
Purpose: To measure the baseline performance of the CCD system.
Description: This activity measures the baseline performance and
commandability of the CCD subsystem. Only primary amplifier D is
used. Bias and Flat Field exposures are taken in order to measure bias
level, read noise, CTE, and gain. Numerous bias frames are taken to
permit construction of "superbias" frames in which the effects of read
noise have been rendered negligible. Full frame and binned observations
are made, with binning factors of 2 x 1, 1 x 2, 2 x 2. Bias frames are
taken in subarray readouts to check the bias level for ACQ and ACQ/PEAK
observations.
Accuracy: 0.1ADU, 0.5e/hr, 0.5e/hr/pixel
Comments on Accuracy: Bial level: better than 0.1 ADU at any position
within the CCD frame; read-out noise negligible
Dark current: good to 0.5 electrons/hour. RMS noise level about 0.5
electrons per hour per pixel. Systematic error in hot pixels may well
exceed this limit.
Products: Possible updates of the following CDBS files: Superbias frames
and Superdark frames. Possible update of the gain, bias level, and
read noise values in ccdtab. Possible flight software updates of table
CCDBiasSubtractionValue. Possible reports in STAN and ISR.
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# THE REST OF THIS FORM IS FOR INTERNAL USE
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# Target information (copy for each target)
Target Name.............................: n/a (internal)
RA.............................................: n/a
Dec...........................................: n/a
Flux (and units)........................: n/a
Visibility window (if known or relevant): n/a
Comment on choice of target: n/a
# Table of exposures (copy for each exposure):
Target or lamp..........................: TUNGSTEN
Type of Acquisition.....................: FLAT
Detector for observation................: STIS/CCD
Operating mode .........................: ACCUM
Spectral Element........................: MIRROR
Aperture................................: 50CCD
Central Wavelength......................:
Exposure Time...........................: 0.1s
Number of Iterations ...................: 2
BOP Predicted Local Count Rate for MAMA.:
BOP Predicted Global Count Rate for MAMA:
ETC PID IDs for Count Rates.............:
Special Requirements or options.........:
Comments: Take exposure every six months
Target or lamp..........................: BIAS
Type of Acquisition.....................:
Detector for observation................: STIS/CCD
Operating mode .........................:
Spectral Element........................: DEF
Aperture................................: DEF
Central Wavelength......................:
Exposure Time...........................: 0
Number of Iterations ...................: 2
BOP Predicted Local Count Rate for MAMA.:
BOP Predicted Global Count Rate for MAMA:
ETC PID IDs for Count Rates.............:
Special Requirements or options.........:
Comments: Take exposure every six months.
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# Special needs of this proposal?
Scheduling: Schedule every six months. Start on September 01, 2009.
Prerequisites: n/a
PDB update? no
On-board table update? no
# Special Requirements:
Real time? N
Special commanding? N
Quick Data turnaround? N
Special timing required? N
Other? N
Describe (& justify) special requirements:
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# Link to Cycle 17 Science
Fraction of science programs supported by this calibration: 60%
List categories of science which can't be executed until after this proposal:
none
why:
List categories of science which are best performed contemporaneous with
this proposal:
none
why:
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Expected FTE weeks for analysis: 3
Required turnaround on analysis (weeks): 3
Data volume (Mb needed for analysis): 10.5Mb
Special software needed for analysis? (Describe): refbias, basejoin,
weekbias, and refaver are needed for the creation of superbiases.
basedarkT, weekdarkT, and daydarkT are needed for the creation of
the superdarks. The 'T' means that there is correction within
each of these procedures that normalizes the temperature on the
Side-2 electronics.
Batchron initially retrieves the gain setting, binning factor and
number of pixels from the bias headers to check that each bias frame
contain the same values. The firstbias frame is used as a reference.
A difference image is then produced from all the biases in each image
set. The difference image along with the reference image are then
used to acquire statistics from defined areas in the difference and
reference biases using the iraf package xdimsum.iterstat. The
statistics are the read noise (mean) and read noise uncertainty
(mean error of the mean). Using these statistics batchron creates
for each gain and bin setting output log and table files.
Description of analysis Plans:
Provides baseline measurements of CCD bias levels, gains, read noise,
charge transfer efficiency, dark current levels, and performance verification
of binning and subarray readpout capabilities. Provides a rough assessment
of changes in flat field features due to dust motes or other particulates.
Numerous bias frames are taken to permit construction of "super bias"
frames in which the effects of read noise have been rendered negligible.
