Observations of asteroids on the Gaia astrometric focal plane

Gaia will be able to carry out remote observations of unprecedented quality, mainly in terms of astrometric accuracy. The Gaia astrometry will be also complemented by high-quality photometric and spectroscopic capability. The part of the focal plane assembly devoted to astrometric measurements consists of an array of 62 CCDs, each having pixels 10×30 μm in size. As a general rule, the CCDs, working in TDI mode, will not be used to obtain two-dimensional images of the observed sources, but only one-dimensional signals along the direction of scan of the satellite. These signals will be produced by the convolution of the radiation received from the sources with the Point Spread Function of the instrument. In this paper we focus on the processing of CCD signals produced by observations of asteroids. We show what information will be extracted from the recorded asteroid signals, and we explain the general approach which will be adopted to build an efficient data reduction pipeline. Finally, we describe the most challenging problems encountered in the CCD processing task for asteroid science applications, and the expected limitations which will affect the performances of data analysis.