Jitter Correction Algorithms for the COROT Satellite Mission

Abstract

The COROT satellite contains a highly accurate stellar photometer with two channels that are respectively optimized for asteroseismology and terrestrial planet finding. The asteroseismology channel can observe 10 bright objects per field for 150 days (long run). At least five different long-run fields will be observed over the spacecraft's lifetime. In order to sample every second, the data that are downloaded must be restricted to fit within the telemetry rate. Each object is therefore assigned a digital mask. The downloaded data will consist of the total electron count within this mask and the barycenter of each star image. Small satellite motions (or jitter) cause some of the flux to fall outside the mask and also cause changes in the position of the barycenter. Here we provide a methodology for using the change in position to correct for flux loss. Different methods are presented, their quality is examined, and the results of the best method(s) are discussed. While our methodology is designed for COROT, it is sufficiently general to be used for any satellite mission with aspirations to long-term, high-precision photometry, such as Kepler.