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Hubble Space Telescope
FOC Instrument Science Report #090

FOC Instrument Science Report #090
							15 Jan 1996
"Results of the Cycle 4 FOC UV Throughput Monitoring Program"
by R. Jedrzejewski

Abstract excerpted from the report:

This report describes the monitoring of the UV throughput of the
FOC by observing a spectrophotometric standard star through four
filter combinations. It is found that the observations through
the F210M filter show a slight decline in senstivity with time of
approximately 4%/year. Observations through the other filters
(F120M, F140M, F170M) show no significant trend. Comparison with
measurements of the UV reflectivity of the WF/PC-1 pickoff mirror
shows that the timescale for decay of contaminants in the hub region
is of order 1 year.