There have been significant improvements in our understanding of the FOS. All FOS data should be recalibrated fully to assure that the latest and most accurate calibration files and the best algorithms are used.
This part of the HST Data Handbook describes the basics of the FOS and is the main source of modern information for understanding, recalibrating, and analyzing FOS spectra. References to more detailed information from other sources-appropriate only for the most expert users and unusual situations-are also provided.
We expect that, as more time passes since the removal of the FOS from HST in February 1997, the predominate users of these chapters will be archival researchers. These investigators may not be as familiar with FOS data and its assessment, calibration, and analysis as the original General Observers (GOs). Accordingly, we have included more detail about instrument operation, data assessment, and calibration than in previous versions of this handbook.
Five chapters are included in the FOS section: