4.1	Analysis Tools

Not all of the tools described in the following sections will be required to analyze all FGS observations. Some of the tools (like binary-fit) are specific to the analysis of Transfer Mode observations, while tools like fgsplot are usable to analyze both Position Mode and Transfer Mode observations.

The following list should serve as a general guide to understanding the processes involved in FGS data analysis which tool to use in a given situation. As always, check the STScI FGS Web site for updates.

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fgsplot

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Used to display a variety of FGS quantities (the location of the FGS Instantaneous Field of View in time as a function of x or y, the fine error signal, the photon counts v. time, etc.). Requires the raw GEIS files a input. Essential for analyzing failed observations and for retrieving useful information from marginal observations.

-	FORTRAN and C modules. Runs in a UNIX and UNIX-based environments.

-	Useful for Position Mode and Transfer Mode observations.

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read-fgs

-	Reads the FGS GEIS header and data files and displays the contents of any of the seven groups of data contained in each data file.

-	FORTRAN and C modules. Runs in a UNIX and UNIX-based environments.

-	Useful for Position Mode and Transfer Mode observations.

•	export-fgs

-	Used to generate ASCII output of the six FGS GEIS header and data file combinations produced for each observation. Useful for non-standard processing and analysis.

-	FORTRAN and C modules. Runs in a UNIX and UNIX-based environments.

-	Useful for Position Mode and Transfer Mode observations.

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gaussfit

-	Used primarily in the analysis and reduction of multi-epoch astrometry data, though is applicable to a wide variety of analysis topics - anything requiring robust, least-squares, or other types of estimation.

-	Primarily C modules. Currently only runs under SUN Solaris and SunOS environments.

-	Primarily used for Position Mode plate overlays, but is also applicable to Transfer Mode and Mixed Mode observations.

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plot-rss

-	Tool to display the residuals of an astrometric catalog generated using gaussfit on CALFGSB output files.

-	FORTRAN and C modules. Runs in a UNIX and UNIX-based environments.

-	Useful for Position Mode observations only.

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ptrans

-	Tool for processing CALFGSA output of Transfer Mode scans.

-	FORTRAN and C modules. Runs in a UNIX and UNIX-based environments.

-	Useful for Transfer Mode observations only.

•	binary-fit

-	Used to model and compare Transfer Mode scans of an unresolved point source with scans of an observed (possibly binary) science target. binary-fit attempts to find a least squares solution to fit the observed S-curve morphology with a superposition of calibration S-curves.

-	FORTRAN and C modules. Runs in a UNIX and UNIX-based environments.

-	Useful for Transfer Mode observations only.