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Paper: Exploratory Studies on How to Improve Gaia Astrometry for Bright Sources
Volume: 527, Astronomical Data Analysis Software and Systems XXIX
Page: 523
Authors: Delgado, A.; Mora, A.; Crowley, C.; Martín–Fleitas, J.; Hernández, J.; Bombrun, A.; Murphy, C.
Abstract: The ESA Gaia spacecraft was designed to produce an astrometric map of the Milky Way covering a wide range of magnitudes. In Gaia Data Release 2, the astrometric performance at the bright end of the magnitude range is dominated by systematics and there is scope for improvement here for future data releases. This work presents some exploratory analyses that aim to improve the calibration of Gaia observations that contain saturated samples. The first method is based on the analysis of targeted full–frame SkyMapper CCD data, obtained using a special engineering mode of the onboard computers for stars brighter than G = 3, which are not observed nominally by Gaia. These observations are highly saturated and require specific processing to extract high quality astrometric information. We outline an algorithm that has been designed and developed to extract centroids from these data. We also explore some calibration methods that can be applied to saturated observations that are obtained nominally in the Astrometric Field CCDs. Different ad–hoc pixel–masking configurations around the saturated samples are explored with a view to better–controlling the calibration link between saturated and non–saturated observations.
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