WFPC2 Technical Instrument Report 02-04:

SMOV3B WFPC2 Photometry Check

-B. Whitmore, I. Heyer

A check of the photometric throughput of the WFPC2 was performed March 31, 2002 (program ID: 8953). The standard star GRW+70d5824 was observed with a selection of filters and the standard star was centered in each of the four CCDs. The data indicate that any changes in the photometric throughputs due to SM3B are less than 1% in most of the visible wavelength filters, and less than a few percent in the UV filters. The distribution shows a mean value of 0.34 +/- 0.26 sigma (where sigma is defined separately for each filter-chip combination) for all the observations, essentially consistent with an unchanged photometric throughput. This corresponds to about 0.4% on an absolute scale. Hence, the response of the WFPC2 was essentially unchanged by the servicing mission. We also find that the long-term throughput decline is consistent with the expected CTE loss.

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