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.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Alcione Mora and Amir Vosteen
Gaia in-orbit realignment: overview and data analysis
", Proc. SPIE 8442, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, 84421Q (August 22, 2012); doi:10.1117/12.926313; http://dx.doi.org/10.1117/12.926313