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Space Telescope Imaging Spectrograph
Phase I: STIS FUV-MAMA Flat-field Monitor

STIS Cycle-18 Calibration Phase-1

Last Revised:					August 30, 2010
Proposal ID:					12417
Title:							STIS FUV-MAMA Flat-field Monitor
PI:							Michael A. Wolfe
Co-I(s):						Charles R. Proffitt

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# Orbit estimates are TOTAL for all of Cycle-18

Total Prime Orbits:             0
External Parallel Orbits:       0
Internals or no-impact orbits:  11
Comments on orbit estimate:     11 single-orbit visits to build S/N

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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:  

This program will obtain FUV-MAMA flat-field observations with the internal
Krypton lamp for the construction of pixel-to-pixel flat-fields (P-flats)
with a S/N of 100 per low-res pixel. The new P-flats are used to study
possible structural changes in the flat-field response of the FUV-MAMA.

Description: 

This program will obtain a set of FUV-MAMA flat-field observations with
sufficient counts to construct pixel-to-pixel flat fields (P-flats) for
all modes. Approximately 11 visits will be required to construct a P-flat 
with S/N = 100 per low-res pixel. Experience with pre-flight and on-orbit 
monitoring flats show that the flat-field characteristics are in large 
measure color- and mode-independent, so that high-quality P-flats 
constructed with the G140M settings should suffice for all FUV-MAMA 
spectroscopic and imaging programs.

This Cycle-18 calibration program calls for obtaining flats with G140M
at five SLIT-STEP positions to illuminate regions of the detector
normally shadowed by the slit fiducial bars. We will use a cenwave of 1470
Ang and the 52X0.1 slit to assess the count rate. If required, we will
adjust the central wavelength to result in approximately 284,0000 counts/s
(ignoring the small decline from one lamp exposure to the next) and achieve
a signal-to-noise of 100/pixel.

Accuracy:				1.0% (0.5% if combined with all previous P-flats)
Comments on Accuracy:	Accuracy is per low-res pixel (2x2 high-res pixels)
Products: 				A reference file (P-flat) and an 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.............................: NONE (Kr lamp)
RA......................................: N/A
Dec.....................................: N/A
Flux (and units)........................: 284,000 count/s (initially)
Visibility window (if known or relevant): N/A

Comment on choice of target: Standard lamp for flat-field exposures.

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

Target or lamp..........................: Krypton
Type of Acquisition.....................: N/A
Detector observation....................: FUV-MAMA
Spectral Element........................: G140M
Aperture................................: 52x0.1
Central Wavelength......................: 1470
Exposure Time...........................: 11x4740 S = 869 M
BOP Predicted Local Count Rate for MAMA.: 0.27 count/s/low-res pixel
BOP Predicted Global Count Rate for MAMA: 284000 count/s
ETC PID IDs for Count Rates.............: [see comments]
Special Requirements....................: SLIT-STEP=-3360, -1680, 0, 1680, 3360

Comments: 	

Count rate based on observations from program 11861. The choice of 
central wavelengths is based upon high lamp output, and avoidance of 
emission lines in the spectra. 

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# Special needs of this proposal?

Scheduling:

Best if observations occur in the Winter of 2010. Visits should be scheduled
such that no more than two visits occur during the same SMS week. This
precaution is to avoid wasting the lamp in case the detector goes to the safe
mode.

Prerequisites: 	(e.g., specific SMOV proposal; command development?)

PDB update?          	No
On-board table update?  No

# Special Requirements:
Real time?                N
Special commanding?       Y
Quick Data turnaround?    N
Special timing required?  N
Other?                    N
Describe (& justify) special requirements:

As the lamp illumination declines, we are obligated to change the central 
wavelength and/or slit width in order to compensate, and so to preserve 
the limited lamp lifetime. In case special commanding is not available for
the required setting, on-board table update will be required.

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# Link to Cycle 18 Science

Fraction of science programs supported by this calibration: 21% (of STIS)
(of all HST GO prime and coordinated parallel usage, excludes snapshot)

List categories of science which can't be executed until after this proposal:
None.

List categories of science which are best performed contemporaneous with 
this proposal:
None.

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# Analysis Plan

Expected FTE weeks for analysis:                                3
Required turnaround on analysis (weeks):                      	16
Data volume (Mb needed for analysis):                         	1000
Special software needed for analysis? (Describe):				None

Description of analysis Plans:	(1-2 paragraphs)

Global count rates and engineering data will be examined to determine the 
extent of lamp degradation, and whether it matches predictions from current 
on-orbit experience.  Flats will be combined, and a solution for the 
slit illumination and spectral distribution of the lamp will be derived 
and removed to create P-flats.