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gimpcor stsdas.hst_calib.fos



gimpcor -- Calculate and display GIMP magnitude for FOS observations.


gimpcor input


The gimpcor task uses the same algorithm as the calibration pipeline task calfos to determine the magnitude of the correction needed to compensate for the Geomagnetic Induced Motion Problem (GIMP) of the FOS instrument.

The task calculates the correction factor that would have been used by calfos and writes its output to standard output (STDOUT). This will give you some idea of the correction factor---both for observing modes that can be corrected on the ground (i.e., most spectroscopy modes) and for those that cannot be directly corrected (spectropolarimetry).

Because this task is a small version of calfos, the output of the two tasks is similar, but gimpcor does not actually perform any corrections. gimpcor also produces some additional output, notably, lines containing the following columns:

        XOFF    The correction in X in diodes.
        YOFF    The correction in Y in Y deflection units.
        B(V3)   The magnetic field, in gauss, along the telescope's
                V1, V2, and V3 axes, respectively.

Each output line corresponds to one packet of data sent from the instrument.


input [string]
The image rootname of the observation for which the GIMP will be calculated.


1. Show the magnitude of the GIMP correction for the observation y0nt0303t. This observation is RAPID-READOUT mode, thus each line corresponds to each readout of the science diodes. This would be similar to most ACCUM spectroscopy modes.

        fo> gimpcor y0nt0303t
        *** CALFOS - Version GIMP VER  ***
        Y0NT0303T  Begin CALFOS for input file rootname: y0nt0303t
        Y0NT0303T  Data quality initialization done using yref$b2f1258ry.r5h
        Y0NT0303T  GIMP corrections calculated from model
        Y0NT0303T  GIMP x scale factor =   0.29500000E+01
        Y0NT0303T  GIMP y scale factor =   0.18880000E+03
        Y0NT0303T  WARNING: GIMP y offsets computed but not applied
        Y0NT0303T       XOFF       YOFF        B(V1)      B(V2)      B(V3)
        Y0NT0303T      0.7937   -18.9236    -0.144756  -0.252337  -0.187240
        Y0NT0303T      0.7774   -22.6758    -0.158107  -0.241623  -0.200176
        Y0NT0303T      0.7540   -26.3918    -0.171826  -0.228918  -0.211748
        Y0NT0303T      0.7235   -29.9800    -0.185674  -0.214425  -0.221575


        Y0NT0303T     -0.1363    30.6008    -0.142325  -0.105515   0.195814
        Y0NT0303T     -0.0940    31.9168    -0.134098  -0.119314   0.193947
        Y0NT0303T  Reduction completed for input file y0nt0303t

2. Doing the same as above for spectropolarimetry data would print GIMP corrections for each position of the polarimeter's waveguide plate. Thus each line would be the correction applied for each pair of data.

3. Doing the same as above for IMAGE mode data would produce a single line of output, corresponding to the average GIMP correction for the whole image.


The GIMP routines do not do any checking of the ground mode of the data. You will need to verify the relevance of the correction magnitudes for your particular data.


Howard Bushouse, STSDAS


For assistance using this or any other tasks, please contact or call the help desk at 410-338-1082.


fos, calfos

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