Accurate Astrometry and Photometry of Saturated and Coronagraphic Point Spread Functions

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For ground-based adaptive optics point source imaging, differential atmospheric refraction and flexure introduce a small drift of the point spread function (PSF) with time, and seeing and sky transmission variations modify the PSF flux. These effects need to be corrected to properly combine the images and obtain optimal signal-to-noise ratios, accurate relative astrometry and photometry of detected companions as well as precise detection limits. Usually, one can easily correct for these effects by using the PSF core, but this is impossible when high dynamic range observing techniques are used, like coronagraphy with a non-transmissive occulting mask, or if the stellar ... continued below

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Marois, C; Lafreniere, D; Macintosh, B & Doyon, R February 7, 2006.

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For ground-based adaptive optics point source imaging, differential atmospheric refraction and flexure introduce a small drift of the point spread function (PSF) with time, and seeing and sky transmission variations modify the PSF flux. These effects need to be corrected to properly combine the images and obtain optimal signal-to-noise ratios, accurate relative astrometry and photometry of detected companions as well as precise detection limits. Usually, one can easily correct for these effects by using the PSF core, but this is impossible when high dynamic range observing techniques are used, like coronagraphy with a non-transmissive occulting mask, or if the stellar PSF core is saturated. We present a new technique that can solve these issues by using off-axis satellite PSFs produced by a periodic amplitude or phase mask conjugated to a pupil plane. It will be shown that these satellite PSFs track precisely the PSF position, its Strehl ratio and its intensity and can thus be used to register and to flux normalize the PSF. This approach can be easily implemented in existing adaptive optics instruments and should be considered for future extreme adaptive optics coronagraph instruments and in high-contrast imaging space observatories.

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PDF-file: 25 pages; size: 1.2 Mbytes

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  • Journal Name: Astrophysical Journal, vol. 647, no. 1, August 10, 2006, pp. 612

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  • Report No.: UCRL-JRNL-218773
  • Grant Number: W-7405-ENG-48
  • Office of Scientific & Technical Information Report Number: 899092
  • Archival Resource Key: ark:/67531/metadc888469

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Office of Scientific & Technical Information Technical Reports

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  • February 7, 2006

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  • Sept. 22, 2016, 2:13 a.m.

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  • Dec. 2, 2016, 7:04 p.m.

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Marois, C; Lafreniere, D; Macintosh, B & Doyon, R. Accurate Astrometry and Photometry of Saturated and Coronagraphic Point Spread Functions, article, February 7, 2006; Livermore, California. (digital.library.unt.edu/ark:/67531/metadc888469/: accessed June 24, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.