Summary: A parametrisation of the quasi-monochromatic line-spread function (LSF) for GAIA is proposed, using an analytical function describing the diffraction wings plus a 'bi-quartic' spline representation of the core. The quasi-monochromatic point-spread function (PSF) is modelled as the product of the along-scan and across-scan LSFs. Two appendices give details on the numerical PSF calculation and on bi-quartic B-splines.

Bibtex entry for this abstract:

@UNPUBLISHED{LL:LL-046,
author = {L.~Lindegren},
title={{N}epresentation of {L}{S}{F} and {P}{S}{F} for {G}{D}{A}{A}{S}-2},
institution={},
year={2003},
month={May},
url={http://www.rssd.esa.int/doc_fetch.php?id=357835},
note={GAIA-LL-046}
}