Abstract
The Fine Guidance Sensor (FGS) system on the Hubble Space Telescope (HST) has been an extremely productive instrument for binary star astronomy. This paper will briefly describe the instrument and discuss the data format for TRANS mode observations, which is used for relative astrometry observations of close binary stars. The data analysis procedures that are typically used will be covered, and a new Fourier-based technique that may be capable of determining component colors of binaries in certain situations will be introduced.
