FOC Instrument Science Report #098 June 9, 1997 "FOC f/48 Spectrophotometric Calibration" by M. Voit and R. Jedrzejewski Abstract excerpted from the report: This report describes the effort to calibrate the spectrophotometric efficiency of the f/48 long-slit spectrograph. Our calibration target was the white dwarf star LDS 749B. We stepped the target across the slit at two different positions, three arcseconds apart, in order to characterize the throughput as a function of target location with respect to the slit. The target fell directly into the slit during one exposure at each of the two slit positions, and we used these observations to calibrate the instrument's spectrophotometric efficiency. Vignetting affects the spectrograph's throughput at both of these locations along the slit, and the difference in efficiency between them agrees with the expected vignetting. Measurements of the spectrograph's efficiency when the centroid lies slightly off the slit unexpectedly shows greater throughput in the blue.
