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Proceedings Paper

Near-infrared coronagraph imager on the Subaru 8 m telescope
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Paper Abstract

We introduce a near-infrared camera named coronagraph imager with adaptive optics (CIAO) mounted on the Subaru 8m telescope. Combined with the Subaru 36 elements adaptive optics (AO), CIAO can produce nearly diffraction limited image with approximately 0.07 arcsec FWHM at K band and high dynamic range imaging with approximately 10 mag difference at 1 arcsec separation under typical seeing conditions. We have carried out performance tests of imaging without and with coronagraph mask since its first light observation held on 2000 February. Because of limited weather conditions, the performance under best seeing conditions has not been tested yet. At a typical natural seeing condition of 0.4 - 0.8 arcsec, halo component of PSF using 0.2 - 0.8 arcsec mask can be reduced up to 70% comparing with that without mask using AO. Even after correction, residual wave front error has typically 1.2 rad2 which corresponds to the Strehl ratio of approximately 0.3 at K band. Such wave front errors degrades the image quality; this is a common problem of coronagraph on the ground-based telescope with non high-order AO. Nevertheless we emphasize that there are various advantages on our coronagraph: the clean PSF of CIAO, reduction of readout noise, and less effect of detector memory problem. Compared with coronagraphs on smaller telescopes, the PSF shape is sharper and it brings higher detectability of sources around bright objects.

Paper Details

Date Published: 7 March 2003
PDF: 8 pages
Proc. SPIE 4841, Instrument Design and Performance for Optical/Infrared Ground-based Telescopes, (7 March 2003); doi: 10.1117/12.460762
Show Author Affiliations
Koji Murakawa, Subaru Telescope/NAOJ (Japan)
Hiroshi Suto, Subaru Telescope/NAOJ (Japan)
Motohide Tamura, National Astronomical Observatory of Japan (Japan)
Hideki Takami, Subaru Telescope/NAOJ (Japan)
Naruhisa Takato, Subaru Telescope/NAOJ (Japan)
Saeko S. Hayashi, Subaru Telescope/NAOJ (Japan)
Yoshiyuki Doi, Subaru Telescope/NAOJ (Japan)
Norio Kaifu, National Astronomical Observatory of Japan (Japan)
Yutaka Hayano, National Astronomical Observatory of Japan (Japan)
Wolfgang Gaessler, Max-Planck-Institut fuer Astronomie (Germany)
Yukiko Kamata, National Astronomical Observatory of Japan (Japan)


Published in SPIE Proceedings Vol. 4841:
Instrument Design and Performance for Optical/Infrared Ground-based Telescopes
Masanori Iye; Alan F. M. Moorwood, Editor(s)

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