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Hubble Space Telescope
FOC Instrument Science Report #094

FOC Instrument Science Report #094
                                                  July 9 1996
"FOC Neutral Density Filter Throughputs"
by W. Hack and M. Voit

Abstract excerpted from the report:

We analyze a series of observations taken with different neutral density
filter combinations yielding new measurements of the neutral density filter
throughputs. This report describes the observation set, the method of
photometry, and how potential problems with the data were avoided. These
new measurements provide a different result from previous internal
calibrations, and various reasons for this discrepancy are discussed at
the end of this report. In general, the 1ND, 2ND and 4ND filters appear to
be within 3% of the expected throughputs for the F430W bandpass. However,
there may be a significant color effect which will be investigated with
further calibration observations.