Documentation on mfcal

Task: mfcal
Purpose: Multifrequency antenna and passband calibration.
Categories: calibration

        MfCal is a Miriad task which determines calibration corrections
        (antenna gains, delay terms and passband shapes) from a
        multi-frequency observation.  The delays and passband are
        determined from an average of all the selected data.  The gains
        are worked out periodically depending upon the user 
        selected interval.

Key: vis
        Input visibility data file. No default. This can (indeed should)
        contain multiple channels and spectral windows. The frequency
        set-up can vary with time.

Key: line
        Standard line parameter, with standard defaults.

Key: edge
        The number of channels, at the edges of each spectral window, that
        are to be dropped. Either one or two numbers can be given, being the
        number of channels at the start and end of each spectral window to be
        dropped. If only one number is given, then this number of channels
        is dropped from both the start and end. The default value is 0.

Key: select
        Standard uv selection. Default is all data.

Key: flux
        Three numbers, giving the source flux, the reference frequency
        (in GHz) and the source spectral index. The flux and spectral index
        are at the reference frequency. If not values are given, then MFCAL
        checks whether the source is one of its known sources, and uses the
        appropriate flux variation with frequency. Otherwise the default flux
        is determined so that the rms gain amplitude is 1, and the default
        spectral index is 0. The default reference frequency is the mean of
        the frequencies in the input data. Also see the `oldflux' option.

Key: refant
        The reference antenna. Default is 3. The reference antenna needs
        to be present throughout the observation. Any solution intervals
        where the reference antenna is missing are discarded.

Key: minants
        The minimum number of antennae that must be present before a
        solution is attempted. Default is 2.

Key: interval
        This gives one or two numbers, both given in minutes, both being
        used to determine the extents of the gains calibration solution
        interval. The first gives the max length of a solution interval. The
        second gives the max gap size in a solution interval. A new solution
        interval is started when either the max times length is exceeded, or a
        gap larger than the max gap is encountered. The default max length is
        5 minutes, and the max gap size is the same as the max length.

Key: options
        Extra processing options. Several values can be given, separated by
        commas. Minimum match is used. Possible values are:
          delay     Attempt to solve for the delay parameters. This can
                    be a large sink of CPU time.
          nopassol  Do not solve for bandpass shape. In this case if a bandpass
                    table is present in the visibility data-set, then it will
                    be applied to the data.
          interpolate Interpolate (and extrapolate) via a spline fit (to
                    the real and imaginary parts) bandpass values for
                    channels with no solution (because of flagging).  If 
                    less than 50% of the channels are unflagged, the 
                    interpolation (extrapolation) is not done and those
                    channels will not have a bandpass solution
          oldflux   This causes MFCAL to use a pre-August 1994 ATCA flux
                    density scale. See the help on oldflux for more
                    information.

Key: tol
        Solution convergence tolerance. Default is 0.001.