STIS Cycle-22 Calibration Phase-1

Last Revised: August 15, 2014
Proposal ID: 13997
Title:	STIS FUV-MAMA Flats
PI: Hugues Sana
Co-I(s): --

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# Orbit estimates are TOTAL for all of Cycle-22

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  aims at  obtaining  FUV-MAMA flat-field  observations to 
create  a new  p-flats with  a SNR of ~100 per (low resolution) pixel. 
The flats are obtained with the Krypton-lamp and the MR grating G140M,
similarly  to the cycle 17,  18 and  20 programs.  However  the  exact 
instrument  setup  (slit  width  and central  wavelength) might change 
depending  on  the desired  count level  (which will  be close  to the 
internally allowed global rate limit).


Description: 
Past  experience  and observations  have  shown  that  ~11 visits  are
sufficient to create a  cumulative image with ~2500 counts/pixel (high
resolution mode,  equivalent to  ~10000 count/pixel in  low resolution
mode). We will start  taking exposure with the setup G140M/52x0.1/1470
(as in the cycle 18 program)  and move to G140M/52x0.1/1420 as soon as
the global rate has  decreased below 180000-190000 counts/sec (maximum
allowed  is ~280000 count/pixels).   On the  basis of  past experience
exposures will be at least 4740 sec long. Hence, all orbits exceed the
1800  s execution  time.  Different visits  will  have different  slit
offsets in order to illuminate  the pixels which are normally shadowed
by the slit bars.


Accuracy: 1.0%   
Comments  on Accuracy:  Accuracy is  per low-res  pixel  (2x2 high-res
pixels)
Products:  combine  this  and  past  cycle frames  to  produce  a  new
reference p-flat and and ISR, as applicable.

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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)........................: <=280000 count/s 
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.: 0.2 count/s/low-res pixel
BOP Predicted Global Count Rate for MAMA: ~220000 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 12417.  Count rate will
change as soon as the instrument setup will be modified.

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# Special needs of this proposal?

Scheduling: About 1 visit per month, to allow inspection of the frames
and timely change  of setup as necessary and to  avoid waste of orbits
in case of lamp failure (as happened in the past).

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 22 Science

Fraction  of science programs  supported by  this calibration:  42% of
STIS total exposure time.

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:                                4
Required turnaround on analysis (weeks):                      	16
Data volume (Mb needed for analysis):                         	100
Special software needed for analysis? (Describe): existing IDL code

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.