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).