WFPC2 Technical Instrument Report 97-01:
Results of the WFPC2 SMOV Relative Photometry Check
-Whitmore, Gonzaga, and Heyer
The photometric throughput of the WFPC2 was essentially unaffected by the 1997 servicing mission. The mean change in throughput is observed/predicted = 0.9984+/-0.0023. The largest deviation is a decline of 0.4+/-0.2% in the PC1. Even this should be considered tentative until new observations become available during the next few months, since it represents only a 2-sigma deviation.