The FOS functioned well to the end of its operational life onboard HST. The instrument was removed from HST on 13 February 1997 during the Second Servicing Mission and was replaced by NICMOS. Any instrumental problems or issues of general community interest will be published here with a dated entry.
The Post-Operational Archives (POA) branch of the Space Telescope - European Coordinating Facility (ST-ECF) has taken over the main responsibility of FOS (re-)calibration. Their web pages contain all of the information that was previously on the STScI FOS pages, supplemented with more recent FOS news including a new and improved version of the FOS calibration pipeline (POA_CALFOS), which replaces CALFOS in the standard IRAF/STSDAS FOS calibration. We invite you to check out their web pages.
(9Dec97) The post-COSTAR, FOS/RED, observed PSF provided in CAL/FOS ISR-148 includes artifacts. The image was created by co-addition of 30 separate data sets. Several of these data sets have been found to contain possible reflection and diffraction effects due to the target's proximity to the edge of the aperture. Therefore the FOS/RED PSF, in particular, should not be used.
ABSTRACT: (30 January 1998) We wish to remind observers that FOS instrumental sensitivity is a very steep function of wavelength shortward of 1200 Anstroms. Although instrumental sensitivity is determined to 3% accuracy in this region, this steep sensitivity gradient requires accurate knowledge of observed wavelengths to insure accurate flux calibration. Common instrumental uncertainties can produce important systematic errors in pipeline processing. See the linked page for the full text of this advisory.
Text listing of older advisories and summaries provided to FOS
observers and archival researchers.
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Maintained by the STScI Spectrographs Group
30 September 1998