WFC3 SMOV4 Analysis Plan: WF34-11447
1.
ID a.
SMOV Activity: WF34 b.
Program ID: 11447 c.
Title: WFC3 IR Dark Current, Noise, Background d.
PI: P. McCullough e.
Requirements addressed: 1.3.4; CEI spec 4.4.8.1 total internal background < 0.4 e-/pix/s (goal: < 0.1) and stable to 10% (4.4.8.2); additional itemization of background from various components in CEI
4.4.8.X. CEI spec 4.8.3 readout noise < 15 electrons RMS in a CDS pair and < 10 electrons in 10 readouts. CEI spec 4.8.11.1-3 bad pixels: < 5% of pixels have response beyond a factor of 2 of the mean response. Less than
2% non-functional pixels (100x nominal dark current or beyond a factor of
4 of mean response). CEI spec 4.8.14 bias stability relates to use of reference pixels.
2.
Expected Datasets a.
Number of external exposures: 24 1024x1024x15; 12
1024x1024x10 b.
Number of external orbits: 4.1 (= 2 nominal + 2.1 CVZ) c.
Number of internal exposures: Each visit, we take 2
1024x1024x5 and 1 1024x1024x15.
d.
Number of internal visits: 20
3.
Time Criticality a.
Real time SMOV activities or impact on SMOV flow:
The 20 internals need to be spread uniformly in time throughout SMOV.
b.
Impact on WFC3 science operations readiness: none c.
Impact on WFC3 pipeline readiness/maturity: none d.
Impact on other calibrations (e.g. SIAF): none e.
Impact on ERO program: none
4.
Analysis Activities a.
One paragraph description: This proposal obtains full-frame, four-amp readout images from un-illuminated internals and some externals. At each of 20 epochs regularly spaced throughout SMOV, we will measure read noise and dark current (of both light-sensitive pixels and reference pixels), using the same IDL code as used in TV3, or slightly tweaked as necessary. We will also identify bad (warm, hot, dead, or variable) pixels. For read noise, dark current, and bad pixels, we will tabulate their time dependence through SMOV. We will also watch for discontinuities in trends, which may indicate some anomaly in the detectors or their operation. Externals aimed at two generic fields, the orbit-pole and the anti-solar directions, will measure diffuse background

light in W and M filters. The latter images will be dark-subtracted and flatfielded nominally, then they will be spatial-median filtered to remove stars and bad pixels; then the global median of each image will be tabulated and compared to expectations from the Instrument Handbook. If the background images show 2-D structure, then 2-D polynomial fits will be performed and coefficients tabulated.
b.
SMOV data dependencies: Flats (internal and/or externals) are called for by the description above, but they aren’t especially necessary for the measurement of the background light, since we are primarily interested in a median value of all pixels.
c.
Ground test data dependencies: The bad pixel mask in orbit should be compared to TV3’s bad pixel mask.
5.
Analysis Team a.
Analysis lead i.
Name: P. McCullough ii.
Days of effort to assess acceptability of dataset: 1 iii.
Days of effort for time critical activities:
N/A iv.
Days of effort for science readiness decision: 3 v.
Days of effort for ISR generation: 5 b.
Analysis Support i.
Name: P. McCullough ii.
Days of effort to assess acceptability of dataset: 1 iii.
Days of effort for time critical activities:
N/A iv.
Days of effort for science readiness decision: 3 v.
Days of effort for ISR generation: 5
6.
Software Tools a.
Name of code: IDL code /user/hilbert/detector_test/idl_procs
(ir_tv3_ron.pro and ir_tv3_dark.pro) b.
Code status: existing scripts may need to be tweaked c.
Heritage: used in TV3 testing d.
Platforms/systems ready to support (primary and redundant): MacBook Pro sky, Linux xo e.
Pre-launch test plan: McCullough will run scripts on TV3 test data and compare to values published by Hilbert using the same scripts.
f.
Test datasets: TBD; will be extracted from TV3 Science Monitors and stored in /grp/hst/wfc3/pmcc/…
7.
Expected Products (ISR, reference files, etc...) ?

a.
Calibration reference files: zero-second-exposure image, dark current image, bad pixel mask b.
Synphot data: read noise, dark current values c.
Other CDBS data: component tables d.
Instrument Science Report provisional title: SMOV
Testing: IR Read Noise, Dark Current, and Backgrounds