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Proceedings Paper

PRAXIS: a near infrared spectrograph optimised for OH suppression
Author(s): S. C. Ellis; S. Bauer; J. Bland-Hawthorn; S. Case; R. Content; T. Fechner; D. Giannone; R. Haynes; E. Hernandez; A. J. Horton; U. Klauser; J. S. Lawrence; S. G. Leon-Saval; E. Lindley; H.-G. Löhmannsröben; S.-S. Min; N. Pai; M. Roth; K. Shortridge; Nicholas F. Staszak; Julia Tims; Pascal Xavier; Ross Zhelem
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Paper Abstract

Atmospheric emission from OH molecules is a long standing problem for near-infrared astronomy. PRAXIS is a unique spectrograph, currently in the build-phase, which is fed by a fibre array that removes the OH background. The OH suppression is achieved with fibre Bragg gratings, which were tested successfully on the GNOSIS instrument. PRAXIS will use the same fibre Bragg gratings as GNOSIS in the first implementation, and new, less expensive and more efficient, multicore fibre Bragg gratings in the second implementation. The OH lines are suppressed by a factor of ~1000, and the expected increase in the signal-to-noise in the interline regions compared to GNOSIS is a factor of ~ 9 with the GNOSIS gratings and a factor of ~ 17 with the new gratings. PRAXIS will enable the full exploitation of OH suppression for the first time, which was not achieved by GNOSIS due to high thermal emission, low spectrograph transmission, and detector noise. PRAXIS will have extremely low thermal emission, through the cooling of all significantly emitting parts, including the fore-optics, the fibre Bragg gratings, a long length of fibre, and a fibre slit, and an optical design that minimises leaks of thermal emission from outside the spectrograph. PRAXIS will achieve low detector noise through the use of a Hawaii-2RG detector, and a high throughput through an efficient VPH based spectrograph. The scientific aims of the instrument are to determine the absolute level of the interline continuum and to enable observations of individual objects via an IFU. PRAXIS will first be installed on the AAT, then later on an 8m class telescope.

Paper Details

Date Published: 9 August 2016
PDF: 13 pages
Proc. SPIE 9908, Ground-based and Airborne Instrumentation for Astronomy VI, 99084A (9 August 2016); doi: 10.1117/12.2232115
Show Author Affiliations
S. C. Ellis, Australian Astronomical Observatory (Australia)
S. Bauer, Leibniz-Institut für Astrophysik Potsdam (Germany)
J. Bland-Hawthorn, The Univ. of Sydney (Australia)
S. Case, Australian Astronomical Observatory (Australia)
R. Content, Australian Astronomical Observatory (Australia)
T. Fechner, Leibniz-Institut für Astrophysik Potsdam (Germany)
D. Giannone, Leibniz-Institut für Astrophysik Potsdam (Germany)
R. Haynes, Leibniz-Institut für Astrophysik Potsdam (Germany)
E. Hernandez, Leibniz-Institut für Astrophysik Potsdam (Germany)
A. J. Horton, Australian Astronomical Observatory (Australia)
U. Klauser, Australian Astronomical Observatory (Australia)
J. S. Lawrence, Australian Astronomical Observatory (Australia)
S. G. Leon-Saval, The Univ. of Sydney (Australia)
E. Lindley, The Univ. of Sydney (Australia)
H.-G. Löhmannsröben, Univ. Potsdam (Germany)
S.-S. Min, The Univ. of Sydney (Australia)
N. Pai, Australian Astronomical Observatory (Australia)
M. Roth, Leibniz-Institut für Astrophysik Potsdam (Germany)
K. Shortridge, Australian Astronomical Observatory (Australia)
Nicholas F. Staszak, Australian Astronomical Observatory (Australia)
Julia Tims, Australian Astronomical Observatory (Australia)
Pascal Xavier, Australian Astronomical Observatory (Australia)
Ross Zhelem, Australian Astronomical Observatory (Australia)

Published in SPIE Proceedings Vol. 9908:
Ground-based and Airborne Instrumentation for Astronomy VI
Christopher J. Evans; Luc Simard; Hideki Takami, Editor(s)

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