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Proceedings Paper

Gaia in-orbit realignment: overview and data analysis
Author(s): Alcione Mora; Amir Vosteen
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Paper Abstract

The ESA Gaia spacecraft has two Shack-Hartmann wavefront sensors (WFS) on its focal plane. They are required to refocus the telescope in-orbit due to launch settings and gravity release. They require bright stars to provide good signal to noise patterns. The centroiding precision achievable poses a limit on the minimum stellar brightness required and, ultimately, on the observing time required to reconstruct the wavefront. Maximum likelihood algorithms have been developed at the Gaia SOC. They provide optimum performance according to the Crámer-Rao lower bound. Detailed wavefront reconstruction procedures, dealing with partial telescope pupil sampling and partial microlens illumination have also been developed. In this work, a brief overview of the WFS and an in depth description of the centroiding and wavefront reconstruction algorithms is provided.

Paper Details

Date Published: 21 September 2012
PDF: 14 pages
Proc. SPIE 8442, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, 84421Q (21 September 2012); doi: 10.1117/12.926313
Show Author Affiliations
Alcione Mora, European Space Astronomy Ctr. (Spain)
Aurora Technology (Netherlands)
Amir Vosteen, TNO (Netherlands)

Published in SPIE Proceedings Vol. 8442:
Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave
Mark C. Clampin; Giovanni G. Fazio; Howard A. MacEwen; Jacobus M. Oschmann, Editor(s)

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