WF/PC Instrument Report 90-06:
A Pre-Flood Checkup on WF/PC Quantum Efficiency Using the STSDAS.SYNPHOT Software Package
-Keith Horne, Eric Wyckoff, Dave Bazell
November 20, 1990
Abstract:
We describe a recent attempt to verify the throughput and quantum efficiency of the WF/PC relative to the pre-flight baseline calibration, using the following filters: F230W, F555W, and F785LP.
Using aperture photometry, the observed count rates were obtained and the aperture corrections applied were based on a mean encircled energy curve. The targets used are not spectrophotometric standards because the WF/PC had not yet measured such standards. Therefore the spectrum of each target is based on ground based photometry and, in some cases, knowledge of the spectral type. The predicted total count rates for the filters were computed from the target spectrum.
The results are in agreement with earlier results from S. Faber, WF/PC IDT. For the F230W filter the rates are 4 times less than predicted, roughly correct for the F555W, and approximately 2 times lower for the F785LP. Because the WF/PC has yet to be UV flooded, the low UV sensitivity is expected. However the low infrared response has yet to be understood. One possibility is that the laboratory measurement was in error.
This report also details the analysis steps using the new STSDAS.SYNPHOT software package.
For more information or a copy of this report, please contact help@stsci.edu.