Artificial incoherent speckles enable precision astrometry and photometry in high-contrast imaging

N. Jovanovic, O. Guyon, F. Martinache, P. Pathak, J. Hagelberg, T. Kudo

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    38 Citations (Scopus)
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    State-of-the-art coronagraphs employed on extreme adaptive optics enabled instruments are constantly improving the contrast detection limit for companions at ever-closer separations from the host star. In order to constrain their properties and, ultimately, compositions, it is important to precisely determine orbital parameters and contrasts with respect to the stars they orbit. This can be difficult in the post-coronagraphic image plane, as by definition the central star has been occulted by the coronagraph. We demonstrate the flexibility of utilizing the deformable mirror in the adaptive optics system of the Subaru Coronagraphic Extreme Adaptive Optics system to generate a field of speckles for the purposes of calibration. Speckles can be placed up to 22.5 λ/D from the star, with any position angle, brightness, and abundance required. Most importantly, we show that a fast modulation of the added speckle phase, between 0 and π, during a long science integration renders these speckles effectively incoherent with the underlying halo. We quantitatively show for the first time that this incoherence, in turn, increases the robustness and stability of the adaptive speckles, which will improve the precision of astrometric and photometric calibration procedures. This technique will be valuable for high-contrast imaging observations with imagers and integral field spectrographs alike.

    Original languageEnglish
    Article numberL24
    Pages (from-to)1-5
    Number of pages5
    JournalAstrophysical Journal Letters
    Issue number2
    Publication statusPublished - 10 Nov 2015

    Bibliographical note

    Copyright 2015 The American Astronomical Society. First published in Astrophysical Journal Letters, 813(2), L24, 2015. The original publication is available at, published by IOP Publishing. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


    • astrometry
    • methods: observational
    • techniques: high angular resolution
    • techniques: photometric


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