OYSTER procedure `dispcorr` is used to compute group delays and dispersion
corrections for the data read from the *.coh* file.

The dispersion corrections are computed for every data point, as well
as the corrections due to the motions of the siderostat pivots. The
latter are solutions for the X, Y, and Z coordinates done by INCHWORM.
They are transformed into delays and interpolated to the time stamps
of the data points by `metrocorr`. Both are applied when the
point data is averaged. (The delay corrections due to pivot motions
are also available in the data file from INCHWORM, in which case
the `astrocorr` procedure is used to just do the interpolation.
The results of both procedures are stored in the same variable.)

Christian Hummel 2009-10-20