@misc{EllisBauerBacigalupoetal.2018,
  author    = {Ellis, S. C. and Bauer, S. and Bacigalupo, C. and Bland-Hawthorn, J. and Bryant, J. J. and Case, S. and Content, R. and Fechner, T. and Giannone, D. and Haynes, R. and Hernandez, E. and Horton, A. J. and Klauser, U. and Lawrence, J. S. and Leon-Saval, S. G. and Lindley, E. and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Min, S. -S. and Pai, N. and Roth, M. and Shortridge, K. and Waller, L. and Xavier, Pascal and Zhelem, Ross},
  title     = {PRAXIS: an OH suppression optimised near infrared spectrograph},
  series = {Ground-based and Airborne Instrumentation for Astronomy VII},
  volume    = {10702},
  journal   = {Ground-based and Airborne Instrumentation for Astronomy VII},
  publisher = {SPIE-INT Soc Optical Engineering},
  address   = {Bellingham},
  isbn      = {978-1-5106-1958-6},
  issn      = {0277-786X},
  doi       = {10.1117/12.2311898},
  pages     = {16},
  year      = {2018},
  abstract  = {The problem of atmospheric emission from OH molecules is a long standing problem for near-infrared astronomy. 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. PRAXIS uses the same fibre Bragg gratings as GNOSIS in its first implementation, and will exploit new, cheaper and more efficient, multicore fibre Bragg gratings in the second implementation. The OH lines are suppressed by a factor of similar to 1000, and the expected increase in the signal-to-noise in the interline regions compared to GNOSIS is a factor of similar to 9 with the GNOSIS gratings and a factor of similar to 17 with the new gratings. PRAXIS will enable the full exploitation of OH suppression for the first time, which was not achieved by GNOSIS (a retrofit to an existing instrument that was not OH-Suppression optimised) due to high thermal emission, low spectrograph transmission and detector noise. PRAXIS has 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 the fibre slit, and an optical design that minimises leaks of thermal emission from outside the spectrograph. PRAXIS has low detector noise through the use of a Hawaii-2RG detector, and a high throughput through a efficient VPH based spectrograph. PRAXIS will determine the absolute level of the interline continuum and enable observations of individual objects via an IFU. In this paper we give a status update and report on acceptance tests.},
  language  = {en}
}
@article{EllisBlandHawthornLawrenceetal.2012,
  author    = {Ellis, S. C. and Bland-Hawthorn, Joss and Lawrence, J. and Horton, A. J. and Trinh, C. and Leon-Saval, S. G. and Shortridge, K. and Bryant, J. and Case, S. and Colless, M. and Couch, W. and Freeman, K. and Gers, L. and Glazebrook, K. and Haynes, R. and Lee, S. and L{\"o}hmannsr{\"o}ben, Hans-Gerd and O'Byrne, J. and Miziarski, S. and Roth, M. and Schmidt, B. and Tinney, C. G. and Zheng, J.},
  title     = {Suppression of the near-infrared OH night-sky lines with fibre Bragg gratings - first results},
  series = {Monthly notices of the Royal Astronomical Society},
  volume    = {425},
  journal   = {Monthly notices of the Royal Astronomical Society},
  number    = {3},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0035-8711},
  doi       = {10.1111/j.1365-2966.2012.21602.x},
  pages     = {1682 -- 1695},
  year      = {2012},
  abstract  = {The background noise between 1 and 1.8 ?mu m in ground-based instruments is dominated by atmospheric emission from hydroxyl molecules. We have built and commissioned a new instrument, the Gemini Near-infrared OH Suppression Integral Field Unit (IFU) System (GNOSIS), which suppresses 103 OH doublets between 1.47 and 1.7?mu m by a factor of 1000 with a resolving power of 10?000. We present the first results from the commissioning of GNOSIS using the IRIS2 spectrograph at the Anglo-Australian Telescope. We present measurements of sensitivity, background and throughput. The combined throughput of the GNOSIS fore-optics, grating unit and relay optics is 36?per cent, but this could be improved to 46?per cent with a more optimal design. We measure strong suppression of the OH lines, confirming that OH suppression with fibre Bragg gratings will be a powerful technology for low-resolution spectroscopy. The integrated OH suppressed background between 1.5 and 1.7 mu m is reduced by a factor of 9 compared to a control spectrum using the same system without suppression. The potential of low-resolution OH-suppressed spectroscopy is illustrated with example observations of Seyfert galaxies and a low-mass star. The GNOSIS background is dominated by detector dark current below 1.67 mu m and by thermal emission above 1.67 mu m. After subtracting these, we detect an unidentified residual interline component of 860 +/- 210 photons s-1 m-2?arcsec-2?mu m-1, comparable to previous measurements. This component is equally bright in the suppressed and control spectra. We have investigated the possible source of the interline component, but were unable to discriminate between a possible instrumental artefact and intrinsic atmospheric emission. Resolving the source of this emission is crucial for the design of fully optimized OH suppression spectrographs. The next-generation OH suppression spectrograph will be focused on resolving the source of the interline component, taking advantage of better optimization for a fibre Bragg grating feed incorporating refinements of design based on our findings from GNOSIS. We quantify the necessary improvements for an optimal OH suppressing fibre spectrograph design.},
  language  = {en}
}