FOS Full Form

FOS Full Form


FOS stand for the Faint Object Spectrograph. The Faint Object Spectrograph (FOS) is one of five scientific instruments under development for use with the Optical Telescope Assembly (OTA) of NASA's Space Telescope. It is a dual-channel spectrograph that operates with two independent 512-channel pulse-counting Digicon. FOS will be employed in connection with the study of scientific questions involving quasars, active galaxies, common distant and local group galaxies, a wide range of objects within the Milky Way and neighboring galaxies, and objects within the Solar System. The FOS consists of an optical bench that supports all optical elements. Dimensional stability was the primary design requirement for the optical bench. It selected a graphite/epoxy structure using laminates with very low coefficients of thermal expansion and high stiffness. Technical requirements are considered and construction details discussed. This handbook describes the faint object spectrograph (FOS) and its use for Cycle 6 of the Hubble Space Telescope General Observer Program. Several presentations have been updated from previous versions, particularly those relating to target acquisition, brightness range, and instrument sensitivity required for exposure and S/N calculations.

This handbook is based on discussion from earlier editions of the handbook, particularly the version 1.0 FOS Instrument Handbook (Ford 1985), the supplement to the version 1.0 instrument handbook (Hartig 1989), and the version 5.0 handbook (Kinney, 1994). For cycle 6 only the current document should be used. The detectors have been described in detail by Harms et al (1979) and Harms (1982). This edition of the FOS Instrument Handbook is for the post-COSTAR refurbished tele-scope. The change in focal length introduced by adding COSTAR affects the size of the aperture as projected onto the sky. However, the pre-costar aperture designations used in the Remote Proposal Submission System, Version 2 (RPS2) and Project Data Base (PDB) have not changed. Apertures throughout this document are referred to by their size in parentheses by their RPS2 exposure level designation (in courier typeface). Indeed, all RPS2 designs used to prepare proposals will be represented in this handbook in Courier typeface. For example, the largest circular aperture is referred to as a 0.9'' (1.0) aperture, while the smallest coupled aperture is referred to as a 0.09'' coupled (0.1-PAIR) aperture.