12 October 2004 Space all-sky imaging with a high angular resolution
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Large surveys at high angular resolution have a lot of interest for astrophysical studies. Their achievements with space missions imply a significant data transmission if a resolution close to 0.1 arcsec is wished. A satisfying telemetry rate is conceivable thanks to a selection of the significant information on board. An image composed of detected stars is first subtracted. A thresholding is then applied in order to keep significant wavelet coefficients. Coding these bright stars as a catalogue with a position and a magnitude estimated on board is less expensive for the telemetry than the coding of their images on the focal plane. Tests were carried out with the technical features of the European astrometric Gaia mission. The consequence of such a lossly compression on the restored images are illustrated. At the end of the space mission, thanks to a combination of fields with different orientations, an improvement of 2 to 3 magnitudes for the detection and a higher resolution are obtained. Even though this approach showed us some difficulties and limits for the Gaia mission, it allowed us to conceive a specific mission dedicated to a full-sky imaging at high angular resolution.
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Claire Dollet, Claire Dollet, Albert Bijaoui, Albert Bijaoui, Francois Mignard, Francois Mignard, "Space all-sky imaging with a high angular resolution", Proc. SPIE 5487, Optical, Infrared, and Millimeter Space Telescopes, (12 October 2004); doi: 10.1117/12.548397; https://doi.org/10.1117/12.548397

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