[ Basic Info | User Guide ]

Basic Information 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 responses) 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 set 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: stokes
        Stokes parameters to process. The default is to process the parallel
        hand polarisations.

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 of each window. The default
        value is 0.

Key: select
        Standard uv selection. The default is to select all data.

Key: flux
        Three to five numbers, giving the source flux density, a reference
        frequency (in GHz) and the source spectral index parameters.
        The flux and spectral index parameters are at the reference frequency.
        If no values are given, then MFCAL checks whether the source is one
        of a set of 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, two or three numbers, all in units of minutes, being
        used to determine the lengths of the antenna gain and passband
        calibration solution interval.
        The first gives the maximum length of a gain solution interval.
        The default is 5 minutes.
        The second gives the maximum gap size in a gain solution interval.
        A new solution interval is started when either the max length is
        exceeded, or a gap larger than the max gap size is encountered.
        The default default max gap size is the same as the max length.
        The third number specifies the passband solution interval.
        The default is a single passband solution for the entire observation.
        Each passband solution interval will consist of one or more
        full gain solution intervals.

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. This option rarely works and
                    should be used with caution.
          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. This is commonly used because
                    a set of channels are flagged, possibly because of RFI or
                    spectral features in the bandpass calibrator.  If
                    less than 50% of the channels are good, the
                    interpolation (extrapolation) is not done and those
                    channels will not have a bandpass solution
          oldflux   This causes MFCAL to use the pre-August 1994 ATCA flux
                    density scale below 11 GHz and and the pre-May 2016 mm
                    fluxscale above 11 GHz.
                    See the help on oldflux for more information.

Key: tol
        Solution convergence tolerance. Default is 0.001.
Revision: 1.20, 2017/05/08 02:31:10 UTC

Generated by miriad@atnf.csiro.au on 08 May 2017