Documentation on gpboot

Task: gpboot
Purpose: Correct the gains table of a visibility data-set.
Categories: calibration

        GpBoot is a MIRIAD program which corrects a visibility data-set's
        gain table.

        GpBoot works by comparing the amplitudes in the gain table of one
        data-set with those of another. The gains are assumed to differ
        by a constant factor. It is assumed that the
        instrumental gain and atmospheric attenuation of the two data-sets
        were the same, and so the difference in gain is due to an
        arbitrary or incorrect flux being specified when initially
        determining the gains.

        GpBoot will also correct for differences in the XY phase offsets
        between the two data-sets, and copy across the polarization
        leakage parameters.

Key: vis
        The input visibility file, containing the gain file to correct.
        The gains and XY phases are assumed to be out by a constant
        factor.

Key: cal
        This is a visibility data-set, which is assumed to contain a
        gain table which scales the data to absolute flux units, and
        contains correct XY phases.

Key: select
        Normal uv-selection parameter. This selects the gains in the
        ``vis'' that are compared against the ``cal'' gains (note that
        all the ``cal'' gains are involved in the comparison). Currently
        ONLY time selection is permitted. You will use this parameter
        to select which time(s) the instrumental/atmospheric amplitude
        gains for ``vis'' are comparable to the observation in ``cal''.

Key: options
        This gives task enrichment parameters. Several can be given,
        separated by commas. Minimum match is used.
          "noxy"      Do not correct for XY phase differences. The
                      default is to correct for this if the ``gains''
                      item is present in both data-sets.
          "nocal"     Do not correct the flux scale. The default is to
                      correct the flux scale if the ``gains'' item is
                      present in both data-sets.