Abstract.
To achieve the science goals of the upcoming ESA space astrometry mission Gaia, it is important that possible disturbing effects on the astrometric measurements are well understood. For example, the accurate measurements of a target star may be disturbed by faint stars, apparently close to the target and therefore not normally detected.
In this work I investigate the detectability of those faint stars by means of computer simulations of a two-dimensional image reconstruction technique. Using the actual scanning law proposed for the Gaia, one-dimensional (1D) images are first simulated, and then, the two-dimensional (2D) images are produced by stacking the 1D images, using a proposed accurate stacking algorithm.
The resulting 2D images are strongly affected by artifacts from the original pixel geometry and the non-uniform distribution of scanning directions, and must be corrected by deconvolution. Using the CLEAN method, the positions as well as the Gaia magnitudes of the point-source objects down to a computed threshold level are precisely obtained and using Monte Carlo simulations, the detection probability as well as the limits for apparent separation and magnitudes are investigated.