WFPC2 Technical Instrument Report 02-03:
SMOV3B WFPC2 UV Contamination Monitoring and Throughput Check
-A. M. Koekemoer, S. Gonzaga, L. Lubin, B. Whitmore, I. Heyer
The throughput of the WFPC2 cameras in the UV is potentially susceptible to significant decreases as a result of contaminants deposited on the cold CCD windows, once the instrument has been cooled down to -88 C. An important part of our SMOV3B checkout involved intensive monitoring of this contamination using the F170W filter, to ensure that the throughput never dropped below levels that can safely be removed by the regular decontamination procedures. We report here the results of these measurements, showing that the throughput remained at safe levels throughput SMOV3B, and in addition demonstrating that the decontamination procedures during SMOV3B returned the throughput to its nominal levels. We also find that the daily contamination rates have now returned to their pre-SMOV3B levels.