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Phase I: NUV Detector Dark Monitor

COS Cycle-18 Calibration Phase-1

Last Revised: October 20, 2010
Proposal ID:  12420
Title: NUV Detector Dark Monitor
PI:	W. Zheng
Co-I(s): C. Proffitt, R. Osten, D. Sahnow

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# Orbit estimates are TOTAL for all of cycle-18; assume 52 weeks) 

Total Prime Orbits:             0
External Parallel Orbits:       0
Internals or no-impact orbits:  52
Comments on orbit estimate:     (e.g. 2 orbit visits, repeated bi-weekly)


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Purpose: 
Perform routine monitoring of MAMA detector dark current. The main purpose is 
to look for evidence of a change in the dark, both to track on-orbit time 
dependence and to check for a detector problem developing.

Description:  
Monitor the NUV detector dark rate by taking TIME-TAG science exposures without
illuminating the detector. Two times every two weeks a 22-min exposure is taken with the
NUV (MAMA) detector with the shutter closed. The length of the exposures is 
chosen to make them fit in Earth occultations.

Accuracy:                       5%
Comments on Accuracy:           
Products:                       CDBS Dark and bad-pixel reference file, ISR


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# Link to Cycle 18 Science

Fraction of science programs supported by this calibration:     ~25% of COS

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.............................:	DARK
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................: NUV MAMA
Operating mode .........................: TIME-TAG
Spectral Element........................: DEF
Aperture................................: DEF
Central Wavelength......................: 
Exposure Time...........................: 1320 s
Number of Iterations ...................: 2
BOP Predicted Local Count Rate for MAMA.: N/A
BOP Predicted Global Count Rate for MAMA: N/A
ETC PID IDs for Count Rates.............: N/A
Special Requirements or options.........: 
Comments: Two exposures bi-weekly


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# Special needs of this proposal?

Scheduling: Two exposures bi-weekly

Prerequisites: None

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):                        0
Data volume (Mb needed for analysis):                           
Special software needed for analysis? (Describe):

Description of analysis Plans:	      (1-2 paragraphs)

We have developed IDL scripts to calculate the dark rate, to check hot pixels 
and to model it time dependence.