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Overall performance of the system


Table gif in Appendix gif gives sensitivity values for ISIS and FOS-2 measured from wide slit observations of spectrophotometric standards, in the case of ISIS with the low dispersion (158 line/mm) gratings. These measurements give the overall performance for the entire system, including atmosphere, telescope, spectrograph and detectors. The performance is expressed as a magnitude (AB magnitude in Oke's system; see for instance Oke, Astrophys. J. suppl. 27, 21, 1974) which gives a measured count rate of 1 photon/second/Å at the detector.

Tue Aug 15 16:42:46 BST 1995