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We demonstrate the effectiveness and robustness of photometric correction algorithms for satellite pointing jitter in the upcoming space mission COROT, which will study asteroseismology and search for exoplanets. Two algorithms based on model-based estimation and decorrelation are tested in two ways: (1) with artificial light sources in the COROTCCD test bench, and (2) with on-orbit photometry from the Canadian MOST(Microvariability and Oscillations of Stars) satellite. Both algorithms effectively correct for pointing jitter to yield the expected results based on the inputs. The test with MOSTdata on a multiperiodic pulsating star demonstrates that the model-based estimation method recovers the oscillation signals better, while the decorrelation technique is more reliable if a poor model of the point-spread function is applied to the data. Therefore, the two algorithms complement one another and should both be applied to COROTphotometry.

The COROTsatellite 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.