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The NIR Upgrade to the SALT Robert Stobie Spectrograph

Andrew I. Sheinis·Marsha J. Wolf·Matthew A. Bershady·David A. H. Buckley·Kenneth H. Nordsieck·Ted B. Williams
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Abstract

The near infrared (NIR) upgrade to the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT), RSS/NIR, extends the spectral coverage of all modes of the visible arm. The RSS/NIR is a low to medium resolution spectrograph with broadband imaging, spectropolarimetric, and Fabry-Perot imaging capabilities. The visible and NIR arms can be used simultaneously to extend spectral coverage from approximately 3200 A to 1.6 um. Both arms utilize high efficiency volume phase holographic gratings via articulating gratings and cameras. The NIR camera is designed around a 2048x2048 HAWAII-2RG detector housed in a cryogenic dewar. The Epps optical design of the camera consists of 6 spherical elements, providing sub-pixel rms image sizes of 7.5 +/- 1.0 um over all wavelengths and field angles. The exact long wavelength cutoff is yet to be determined in a detailed thermal analysis and will depend on the semi-warm instrument cooling scheme. Initial estimates place instrument limiting magnitudes at J = 23.4 and H(1.4-1.6 um) = 21.6 for S/N = 3 in a 1 hour exposure well below the sky noise.

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Andrew I. Sheinis, Marsha J. Wolf, Matthew A. Bershady, David A. H. Buckley, Kenneth H. Nordsieck, Ted B. Williams. 2006-06-05. The NIR Upgrade to the SALT Robert Stobie Spectrograph. https://doi.org/10.1117/12.673533

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