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Proceedings Paper

VXMS: the VISTA extreme multiplex spectrograph
Author(s): Robert Content; Tom Shanks; Ray Sharples; David Bramall; Will Percival
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Paper Abstract

A study for a spectrograph delivering at least 10000 slits for galaxies and 20000 for stars over a 2.5 deg2 field have been completed as an answer to the call for proposal for future VISTA MOS instrumentation. In a single night, 65000 galaxy redshifts can be measured to z~0.7 and beyond for measuring the Baryon Acoustic Oscillation (BAO) scale and many other science goals. The design features ten cloned spectrographs which give a smaller total weight and length than a unique spectrograph to make it placable in the space envelope of the Cassegrain focus. The clones use a transparent design including a grism in which all optics are about the size or smaller than the clone rectangular subfield so that they can be tightly packed with little gaps between subfields. Only low cost glasses are used; the variations in chromatic aberrations between bands are compensated by changing a box containing the grism and two adjacent lenses. Two bands cover the 550nm to 900nm wavelength range at resolution of 1100 for blue end and 3000 for red end while another cover the Calcium triplet at 5000. An optional box does imaging but we studied different innovative methods for acquisition without imaging. A new 2.3° corrector was designed that places the pupil before and relatively near the focal plane which permits to give more space at the back of the spectrographs by placing them in a hedgehog configuration. An offaxis field lens in each spectrograph permits to control the pupil position.

Paper Details

Date Published: 24 September 2012
PDF: 8 pages
Proc. SPIE 8446, Ground-based and Airborne Instrumentation for Astronomy IV, 844664 (24 September 2012); doi: 10.1117/12.927260
Show Author Affiliations
Robert Content, Australian Astronomical Observatory (Australia)
Univ. of Durham (United Kingdom)
Tom Shanks, Univ. of Durham (United Kingdom)
Ray Sharples, Univ. of Durham (United Kingdom)
David Bramall, Univ. of Durham (United Kingdom)
Will Percival, Univ. of Portsmouth (United Kingdom)

Published in SPIE Proceedings Vol. 8446:
Ground-based and Airborne Instrumentation for Astronomy IV
Ian S. McLean; Suzanne K. Ramsay; Hideki Takami, Editor(s)

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