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STIS Cycle 19 Calibration Phase 1

Last Revised: November 1, 2013
Proposal ID: 13543
Title: Slit Wheel Repeatability
PI: Audrey DiFelice
Co-I(s): C. Long, C. Proffitt

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# orbit estimates are TOTAL for all of cycle 20; assume 52 weeks

Total Prime Orbits: 0
External Parallel Orbits: 0
Internals or no-impact orbits: 1
Comments on orbit estimate:


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Purpose:
Test the repeatability of the slit wheel by taking a sequence of comparison lamp spectra with grating G230MB (2697) and the three smallest long slits (52X0.2, 52X0.1, and 52X0.05). This is a clone of Cycle 20 Program 13140.

Description:
Verify the repeatability of the slit wheel for three STIS slits
(52X0.2, 52X0.1, and 52X0.05) by taking images with the Pt/Cr/Ne LINE lamp and the CCD detector. Use the G230MB (2697) grating with the CCD, and rotate the slit wheel among the 3 chosen slits.
Detector: CCD
Grating: G230MB (2697)
Slits: 52x0.2, 52X0.1, 52X0.05
Grating A: 52X0.2 (10 seconds)
Grating B: 52X0.1 (10 seconds)
Grating C: 52X0.05 (20 seconds)
Sequence: A-B-C-B-C-A-A-B-A-C-B-B-A-B-C-B-C-C-A-B-A-C-B-A
Forward motion: B - 4 times, C - 6 times
Backward motion: A - 6 times, B - 4 times
No motion: A/B/C - 1 time.

Accuracy: 0.2 pixel
Comments on Accuracy: after removing the zero-order shift
Products: report

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Fraction of science programs supported by this calibration:
53% 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:
Take spectra of LINE lamp at various slit positions.

# Target information (copy for each target)

Target Name.............................: LINE
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..........................: Pt/Cr/Ne LINE
Type of Acquisition.....................: N/A
Detector for observation................: CCD
Operating mode .........................: ACCUM
Spectral Element........................: G230MB
Aperture................................: 50X0.2, 50X0.1, 50X0.05
Central Wavelength......................: 2697
Exposure Time...........................: 10, 20s
Number of Iterations ...................: 1
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.........: NON-INT
Comments: perform once early in cycle

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# Special needs of this proposal?

Scheduling: early in Cycle 21

Prerequisites: None

PDB update? None
On-board table update? None

# 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

We will use the ‘wavecal’ function in PyRAF and polynomial thermal modeling to analyze the data.

Expected FTE weeks for analysis: 1
Required turnaround on analysis (weeks): 4
Data volume (Mb needed for analysis): 24 CCD images at 2.2 MB each (52.8 MB total)
18 reference files at 56.9 MB total

Special software needed for analysis? (Describe):

Description of analysis plans: The *_raw.fits observation files will be processed through the ‘wavecal’ function in PyRAF (using a copy of the *_raw.fits file in place of the wavecal file). The shifts in the dispersion (SHIFTA1) and spatial (SHIFTA2) directions can then be extracted from the file header. The first observation taken with each slit is then used as a reference point, and all other observations are zeroed to that point. Finally, the thermal effects in both the dispersion and the spatial direction are modeled as a second-order polynomial and removed from the shifts.