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STIS Cycle-19 Calibration Phase-1

Last Revised: July 22, 2011
Proposal ID: 12776
Title: STIS Cycle 18 MAMA Dark Monitor
PI: Colin Cox
Co-I(s): C. Proffitt, R. Osten

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# Orbit estimates are TOTAL for all of cycle-19; assuming 52 weeks)

Total Prime Orbits: 0
External Parallel Orbits: 0
Internals or no-impact orbits: 116
Comments on orbit estimate: 1 orbit per MAMA, 2 executions bi-weekly
for 52 weeks (2 x 52 x 2 detectors)
plus extra 2 x 6 orbit blocks for FUV MAMA


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Purpose:
This proposal monitors the behavior of the dark current in each of the MAMA
detectors. This proposal will provide the primary means of checking on health
of the MAMA detectors systems through frequent monitoring of the background
count rate. The purpose is to look for evidence of change in the dark rate,
indicative of detector problems developing.

Description:

Two times bi-weekly one exposure of 1380s is taken with the FUV and NUV MAMAs with the
shutter closed. For each detector, the second exposure in the bi-weekly pair should be
taken 4.5 to 7.5 orbits after the first exposure of the pair. This ensures they are
taken in different parts of the same SAA free interval. The exposures are taken in
ACCUM mode. The length of the exposures is chosen to make them parallels. Two times
a year a six-exposure sequence of 1314s FUV-MAMA TIME-TAG darks are taken over the
course of a single SAA free period.

Semi-annual exposure groups: Twice a year take five 1314 s FUV MAMA
dark observations during a single SAA free period. Distribute these exposures
as uniformly as possible over the SAA free block of orbits. Similarly for the
NUV do blocks of five 3x314s ACCUM exposures. The first visit of each of these
groups contains one or more "BETWEENS" to force the observations to occur
during one of the weeks that the LRP has MAMA external observations planned.

Accuracy: 5%
Comments on Accuracy: Each measurement will give a statistical
uncertainty of 5% for the global dark rate.
Products: CDBS DRK files; ISR

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Fraction of science programs supported by this calibration:
47% of STIS total exposure time.

List categories of science, which can't be executed until after this proposal:
why:

List categories of science which are best performed contemporaneous with
this proposal:
why:


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# THE REST OF THIS FORM IS FOR INTERNAL USE
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Observation summary:


# Target information (copy for each target)

Target Name.............................: N/A
RA......................................: N/A
Dec.....................................: N/A
Flux (and units)........................: N/A
Visibility window (if known or relevant): N/A
Comment on choice of target:

# Exposure list plan at the Phase I level. Be as complete as reasonable.
# If possible information should be complete enough to allow easy
# submission of a Phase 2 from this form. However, if you have to leave
# some of the fields blank below, or want to provide the information
# in another format, that is acceptable. (Make sure you do the BOP checking
# though, as this is a phase-1 issue.)

Table of exposures (copy for each exposure as appropriate/desired):

Target or lamp..........................: DARK
Type of Acquisition.....................: None
Detector for observation................: STIS FUV MAMA
Operating mode .........................: ACCUM
Spectral Element........................: DEF
Aperture................................: DEF
Central Wavelength......................:
Exposure Time...........................: 1380 s
Number of Iterations ...................: 2
BOP Predicted Local Count Rate for MAMA.: 1E-5 c/s/p
BOP Predicted Global Count Rate for MAMA: 10 c/s
ETC PID IDs for Count Rates.............: N/A
Special Requirements or options.........:
Comments: Schedule two visits every two weeks for each detector

Target or lamp..........................: DARK
Type of Acquisition.....................: None
Detector for observation................: STIS NUV MAMA
Operating mode .........................: ACCUM
Spectral Element........................: DEF
Aperture................................: DEF
Central Wavelength......................:
Exposure Time...........................: 1380 s
Number of Iterations ...................: 2
BOP Predicted Local Count Rate for MAMA.: 1E-3 c/s/p
BOP Predicted Global Count Rate for MAMA: 1500 c/s
ETC PID IDs for Count Rates.............: N/A
Special Requirements or options.........:
Comments: Schedule two visits every two weeks for each detector

Target or lamp..........................: DARK
Type of Acquisition.....................: None
Detector observation....................: STIS/FUV-MAMA/TIME-TAG
Spectral Element........................: DEF
Aperture................................: DEF
Central Wavelength......................:
Exposure Time...........................: 1314 s
BOP Predicted Local Count Rate for MAMA.: 1e-5 c/s/p
BOP Predicted Global Count Rate for MAMA: 10 c/s
ETC PID IDs for Count Rates.............: N/A
Special Requirements....................:
Comments: Six visits grouped in a single SAA free period twice per year

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# Special needs of this proposal?

Scheduling: Schedule two visits every two weeks for each detector.

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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# Analysis Plan

Expected FTE weeks for analysis: 4
Required turnaround on analysis (weeks): 4 weeks
Data volume (Mb needed for analysis): 50Mb
Special software needed for analysis? (Describe): None

Description of analysis Plans:

Measure dark current and look for evidence of change in dark indicative of
detector problem developing. Data will be co-added each month and compared to
previous months (same for periods of 6 months). Develop temperature dependant
NUV darks as well as FUV darks for various glow levels. Create DRK images for
pipeline.

Based on the Cycle-18 experience, we will use IDL and IRAF scripts to calculate
the dark rates, and produce combined dark image for reference. We will use
existing IDL scripts to model the trend of NUV dark rate and predict its future
values.