THE ASTRO OPTICAL RESPONSE MODEL

摘要

We define a numerical description of the signal model for the Gaia astrometric instrument, encoded in the focal plane to sky mapping (FPSM) function, i.e., the transformation between object and image space, and encoded in terms of discrepancy with respect to the geometric optics. We calculate the FPSM for several spectral types, also deriving the chromaticity map. This model can be extended to take into account dynamic contributions, e.g., attitude or TDI errors. The signal distribution is evaluated to estimate the systematic and random error at the elementary exposure level, and scaled to equivalent final mission performance by means of a simple transformation. We describe the possible future development of the model into a more detailed realistic representation of the Gaia astrometric measurement.