@article{BlandHawthornEllisLeonSavaletal.2011,
  author    = {Bland-Hawthorn, Joss and Ellis, S. C. and Leon-Saval, S. G. and Haynes, R. and Roth, Martin M. and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Horton, A. J. and Cuby, J. -G. and Birks, T. A. and Lawrence, J. S. and Gillingham, P. and Ryder, S. D. and Trinh, C.},
  title     = {A complex multi-notch astronomical filter to suppress the bright infrared sky},
  series = {Nature Communications},
  volume    = {2},
  journal   = {Nature Communications},
  number    = {50},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {2041-1723},
  doi       = {10.1038/ncomms1584},
  pages     = {7},
  year      = {2011},
  abstract  = {A long-standing and profound problem in astronomy is the difficulty in obtaining deep near-infrared observations due to the extreme brightness and variability of the night sky at these wavelengths. A solution to this problem is crucial if we are to obtain the deepest possible observations of the early Universe, as redshifted starlight from distant galaxies appears at these wavelengths. The atmospheric emission between 1,000 and 1,800 nm arises almost entirely from a forest of extremely bright, very narrow hydroxyl emission lines that varies on timescales of minutes. The astronomical community has long envisaged the prospect of selectively removing these lines, while retaining high throughput between them. Here we demonstrate such a filter for the first time, presenting results from the first on-sky tests. Its use on current 8 m telescopes and future 30 m telescopes will open up many new research avenues in the years to come.},
  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}
}