Besides developing the pipeline to reduce the astrometric data from the Hubble Space Telescope, we produced two more general use computer programs, GaussFit and Pickles.
GaussFit was developed as a platform to facilitate the solution of least squares and robust estimation problems for astrometric data reduction with data from the Hubble Space Telescope. It provides an easy and natural way to formulate general nonlinear problems; problems where the observation equations (equations of condition) contain more than one observation (the errors-in-variables case); problems with correlated observations; problems where exact constraints among parameters must be enforced. Certain robust estimation methods that generalize least squares to non-euclidian metrics and provide greater immunity against "outliers" than does the classical least squares method are available. GaussFit runs both under UNIX and VMS and there is a Macintosh version.
Pickles is a Macintosh program that was first developed by the HST Astrometry Team as a tool for determining pointings and rolls of the Hubble Space Telescope when desired target and guide stars were in the fine guidance sensor "pickles". Because of its ability to extract and display star positions from the Guide Star Catalog, ACRS, SAO, AGK3 catalog CD ROMs, pickles is also being used in other astronomical proj ects. Pickles is a powerful, easy-to-use tool for visualization of star positions for any purpose.
