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Basic Information on gpedit


Task: gpedit
Purpose: Edit the gain table.
Categories: calibration

        Gpedit is a MIRIAD task which modifies calibration tables.

Key: vis
        The input visibility file, containing the gain file to modify.
        No default.

Key: select
        Normal uv data selection commands. See the help on select for
        more information. Currently only antenna, time, and amplitude
        selection is supported. The amplitude selection applies to the
        gains, not the uv-data, and can be used to flag or replace bad
        gain amplitudes. The default is to select everything.

Key: feeds
        The polarisation feeds affected (e.g. R, L, X or Y). Default is
        all feeds.

Key: gain
        This gives the complex-valued gain used in the `multiply' and
        `replace' options (see below). It is given as an amplitude
        and phase (in degrees). For example gain=2,90 produces a gain
        with a amplitude of 2 and phase of 90 degrees.
        The first two values specify the continuum solution, if there is
        a gain table with n binned solutions, another n*2 values can be
        specified. The default is 1,0 for all gains.

Key: options
        This gives extra processing options. Several values can be given,
        separated by commas. Option values can be abbreviated to
        uniqueness.
 
        The following options operate on the gains:
          replace   The existing gains are replaced by the value
                    given by the `gain' keyword. NOTE: If no other
                    options are given, the replace option is performed.
          multiply  The existing gains are multiplied by the gain
                    given by the `gain' keyword.
          flag      The existing gains are flagged as bad.
          amplitude The phases of the existing gains are set to 0.
          phase     The amplitudes of the existing gains are set to 1.
          scale     The phase of the gains is multiplied by the factor
                    given by the `gain' keyword.
          dup       Convert a single-polarization gain table into a dual
                    polarization table.
          invert    The existing gains are inverted (1/gain, phase
                    negated) to allow undoing calibration that has been
                    applied to the uvdata with uvaver.
 
        The following option operates on the polarization leakages:
          reflect   The existing leakages are made to possess a
                    symmetry: For each antenna, we make
                    DX = -conjg(DY).
          zmean     Subtract an offset, so that the mean leakage is 0.
 
        The following option operates on the bandpass table:
          extend    Extend the bandpass table to cover the full range of
                    channels in the data. Use gain=0 to extend the
                    range by replicating the edge value and gain=1 to use
                    linear extrapolation of the edge values.
          hanning   Hanning smooth the bandpass. (Miriad actually uses
                    binomial smoothing when it claims to use hanning)
          boxcar    Boxcar smooth the bandpass (i.e., running average)

Key: width
        The smoothing width for hanning or boxcar smoothing of the
        bandpass. Width will be increased to next odd number if even.
        Default and minimum value is 3. Maximum is 33 for hanning,
        and 257 for boxcar smoothing.
 
        Example:
          gpedit vis=cyga gain=14.4,90 select=ant(1,2) feeds=X
          gpedit vis=cyga options=boxcar width=15

Generated by miriad@atnf.csiro.au on 21 Jun 2016