The testfgs package performs analyses that use data from the Fine Guidance Sensors, such as measuring accurate positions of stars or determining the separation and relative magnitudes of close binary stars. FGS files are modified in-place by all of the tasks in this package.
Calibrating an FGS data set involves the following steps (in this order):
1 - Use 'dqmgen' to generate a data quality mask for the FGS file. 2 - Obtain fill values of missing data and the end of the array from the input data file header. Valid data values will be flagged with the value "OKVAL". 3 - Correct photomultplier count rates for deadtime and dark count using the 'pmtcorr' task. 4 - Correct star selector encoder readings using the 'ssecorr' task. 5 - Remove particle events from photomultiplier counts using the 'parthitf' task. After performing this step, the mask file is no longer needed. 6 - Use the 'puttime' task to assign observation times to the FGS data stream. 7 - Compute the centroided encoder positions using the 'centroid' task. 8 - Insert the rotation quaternion into the FGS data table using the 'fquat' task. 9 - Coordinates can now be converted to other forms using the tasks 'fpts' (pickle to spacecraft coordinates), 'fste' (spacecraft to equatorial coordinates), and 'fstg' (spacecraft to gnomonic coordinates).For more information about using the testfgs package, see the individual task help files, or see the "STSDAS User's Guide".