PRAXIS: an OH suppression optimised near infrared spectrograph

S. C. Ellis*, J. Bland-Hawthorn, S. Bauer, S. Case, R. Content, T. Fechner, D. Giannone, R. Haynes, E. Hernandez, A. J. Horton, U. Klauser, J. S. Lawrence, S. G. Leon-Saval, H. G. Löhmannsröben, S. S. Min, N. Pai, M. Roth, L. Waller, Ross Zhelem

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contributionpeer-review

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The problem of atmospheric emission from OH molecules is a long standing problem for near-infrared astronomy. We are now close to solving this problem for the first time with the PRAXIS instrument. PRAXIS is a unique spectrograph which is fed by fibres that remove the OH background, and is optimised specifically to benefit from OH-Suppression. The OH suppression is achieved with fibre Bragg gratings, which were tested successfully on the GNOSIS instrument. The OH lines are suppressed by a factor of ∼1000, leading to a reduction of the integrated background of a factor 9. A future upgrade to multicore fibre Bragg gratings will further increase this reduction. PRAXIS has had two commissioning runs, with a third commissioning run planned for July 2019, which will be presented at the conference. PRAXIS has a measured throughput of 20 %, demonstrating high efficiency in an OH suppression instrument for the first time. Science verification observations of Seyfert galaxies demonstrate the potential of OH suppression.

Original languageEnglish
Title of host publicationAdvances in Optical Astronomical Instrumentation 2019
EditorsSimon Ellis, Céline d'Orgeville
Place of PublicationBellingham, Washington
Number of pages2
ISBN (Electronic)9781510631472
ISBN (Print)9781510631465
Publication statusPublished - 6 Jan 2020
EventAdvances in Optical Astronomical Instrumentation 2019 - Melbourne, Australia
Duration: 9 Dec 201912 Dec 2019

Publication series

NameProceedings of SPIE
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceAdvances in Optical Astronomical Instrumentation 2019

Bibliographical note

Copyright 2020 Society of Photo-Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.


  • Astrophotonics
  • Fibre Bragg gratings
  • Near infrared
  • OH suppression
  • Spectroscopy


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