STScI Logo

Hubble Space Telescope
Phase I: COS NUV Spectroscopic Sensitivity Monitor

COS Cycle-18 Calibration Phase-1 Template

Last Revised:			08 Oct. 2010
Proposal ID:			12421
Title:				COS NUV Spectroscopic Sensitivity Monitor
PI:				R. A. Osten
Co-I(s):			C. Proffitt, A. Aloisi

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

Total Prime Orbits:             12
External Parallel Orbits:       0
Internals or no-impact orbits:  0
Comments on orbit estimate:     observations quarterly: 3x2 for G230L, 3x2 for M modes


---------------------------------------------------------------------------
# This section should be written with a GO audience in mind -- use 
# Calibration plans in WFPC-2 handbook as a guide.

Purpose:                        Monitor sensitivity of each NUV grating mode to detect any change 
          due to contamination or other causes.

                                      
Description:  Obtain exposures in all NUV gratings --- G230L, G185M,
	      G225M, and G285M -- quarterly.  The first two gratings
	      have stable behavior, while the last two are experiencing
	      sensitivity declines.  However, they are rarely used in
	      Cycle 18 so quarterly observations will suffice to monitor
	      the trends.
              Main goal is to 
              track time dependence of sensitivity as a function of 
              wavelength 

Accuracy:                       SNR of 30 per resel at the central wavelength
Comments on Accuracy:           
Products:                       ISR, Time-Dependent Sensitivity reference files


---------------------------------------------------------------------------
# Link to Cycle 18 Science
# Use the GO + GTO Phase 1 exposure  listing and derived statistics
# posted on WWW.

Fraction of science programs supported by this calibration:      8.1% of COS exposures
are NUV gratings (by exposure time); this breaks down into 6.8% for L-modes and
1.3% for M modes.

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:


---------------------------------------------------------------------------
# THE REST OF THIS FORM IS FOR INTERNAL USE
---------------------------------------------------------------------------
Observation summary:  Take spectra of WD1057+719 in G230L monthly in central
wavelengths 2635, 2950; every quarter add in exposures of 3360 cenwave.
Take spectra of G191B2B in the M-modes every quarter.

# Target information (copy for each target)

Target Name.............................:	WD1057+719
RA......................................:			
Dec.....................................:		
Flux (and units)........................:	
Visibility window (if known or relevant):
Comment on choice of target:

Target Name.............................:	G191B2B
RA......................................:			
Dec.....................................:		
Flux (and units)........................:	
Visibility window (if known or relevant):
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..........................: e.g. G191B2B, or HITM
Type of Acquisition.....................: e.g. ACQ-PEAK
Detector for observation................: e.g. CCD
Operating mode .........................: e.g. ACCUM or TIMETAG
Spectral Element........................: e.g. G430L
Aperture................................: e.g. 50x0.5
Central Wavelength......................: e.g. 4300
Exposure Time...........................: e.g. 300s, crsplit=2 
Number of Iterations ...................: e.g. 1
BOP Predicted Local Count Rate for MAMA.:
BOP Predicted Global Count Rate for MAMA:
ETC PID IDs for Count Rates.............:
Special Requirements or options.........: (e.g. GAIN=4; LOW-SKY)
Comments: (e.g. if monitoring, specify frequency) 


---------------------------------------------------------------------------
# Special needs of this proposal?

Scheduling: as indicated above

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

PDB update?               (Specify table name if known e.g. SIAF).
On-board table update?    (Specify table name if known e.g. CCDBadPixelTable)

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

-------------------------------------------------------------------------
# Analysis Plan

Expected FTE weeks for analysis:                                3
Required turnaround on analysis (weeks):                        1
Data volume (Mb needed for analysis):                           0
Special software needed for analysis? (Describe):  existing IDL programs 

Description of analysis Plans:  Use existing IDL code to make ratios of spectra with
those obtained at the beginning of the monitoring.  After averaging in wavelength,
plots of these trends with time determine the time-dependent sensitivity.  These values
are used to update TDS reference files.