Faint object spectrograph for the William Herschel Telescope

Jeremy R. Allington-Smith; J. Mike Breare; Richard S. Ellis; Ian Robert Parry; John Webster; David W. Gellatly; Susan P. Worswick

doi:10.1117/12.19116

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1 July 1990 Faint object spectrograph for the William Herschel Telescope

Jeremy R. Allington-Smith, J. Mike Breare, Richard S. Ellis, Ian Robert Parry, John Webster, David W. Gellatly, Susan P. Worswick

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Proceedings Volume 1235, Instrumentation in Astronomy VII; (1990) https://doi.org/10.1117/12.19116
Event: SPIE Astronomical Telescopes and Instrumentation for the 21st Century, 1990, Tucson, AZ, United States

Abstract

The design and performance of the FOS-2 faint-object spectrograph for the Herschel Telescope at the Observatorio del Roque de los Muchachos are described and illustrated with diagrams and drawings. The FOS-2 has an image scale of 223 microns/arcsec at the slit and features a cryostat-cooled 385 x 578-pixel CCD detector with 22-micron-sq pixels, operating with resolution 1.5 pixels and dispersion 8.73 A/pixel at 460-970 nm (first order) or 4.32 A/pixel at 350-490 nm (second order). The high-efficiency optical system is of the type described by Wynne (1982) and operates in the diverging f/11 Cassegrain beam without a collimator. Overall system efficiency in first order with a 5-arcsec slit has a peak at 16 percent at 700 nm and remains above 1 percent at all wavelengths imaged by the CCD; in second order the peak efficiency is about 3 percent at 490 nm and remains above 1 percent except below 370 nm. The mechanical system, the control and data acquisition procedures, and the data-reduction software are briefly discussed.

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Jeremy R. Allington-Smith, J. Mike Breare, Richard S. Ellis, Ian Robert Parry, John Webster, David W. Gellatly, and Susan P. Worswick "Faint object spectrograph for the William Herschel Telescope", Proc. SPIE 1235, Instrumentation in Astronomy VII, (1 July 1990); https://doi.org/10.1117/12.19116

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