Basic Information on mfboot

Task: mfboot
Purpose: Set the flux scale of a visibility dataset.
Categories: calibration

        MFBOOT is a MIRIAD program that corrects the flux scale in
        visibility datasets. In doing this, it assumes that the flux
        density scale is out by a constant scale factor. MFBOOT computes
        and applies a scale factor to the calibration tables of visibility
        datasets to account for this.
 
        To determine this factor, MFBOOT compares the flux
        density of measured visibilities with models of the expected
        visibility. The visibilities can correspond to measurements of
        planets or point sources. For point sources, they can be either
        standard calibrators with known flux density, or others. In the
        latter case the user must specify its flux density.
 

Key: vis
        Input visibility datasets. Several datasets can be given (wildcards
        are supported).  The scale factor will be applied uniformly to all
        datasets whether or not they contain the source used to determine it.

Key: line
        Normal uv data line parameter, with the normal defaults. See
        the help on line for more information.

Key: select
        Normal uv-selection parameter. This selects the data in the input
        datasets to analyse. The data selected should consist of
        a single planet or point source. See the help on ``select'' for more
        information. For planets, you may wish to select just the shortest
        spacing, where the planet is strongest.

Key: flux
        Three to five numbers, giving the source flux density, a reference
        frequency (in GHz), the source spectral index and optionally two
        higher order terms. The flux and spectral index are at the reference
        frequency. If no values are given, then MFBOOT checks whether the
        source is one of a set of known sources or a planet, and uses
        the appropriate flux variation with frequency.
        MFBOOT has built-in models for a few calibrators as well as the
        planets - see calplot and plplt.
 
        For a point source, this parameter gives the flux density of the
        calibrator in Janskys. For a planet, this parameter gives the
        brightness temperature of the planet in Kelvin.

Key: mode
        MFBOOT can process the data in one of three modes: "triple", "scalar"
        and "vector". The default is "triple" for point sources and "scalar"
        for planets.
 
        In "triple" mode, MFBOOT compares the triple product of the data
        and model. The advantage of comparing triple products is that the
        process is robust to phase errors, and the data do not need to be
        phase calibrated. Because planets can be significantly resolved,
        triple mode is often not appropriate for them. However if the
        resolution is modest on the selected baselines, triple mode can
        be used.
 
        In "scalar" mode, the amplitude of the data and model are compared.
        This is also robust to phase errors, but will experience a noise
        bias when the signal to noise is poor. Planets are often sufficiently
        strong that noise bias is not an issue.
 
        In "vector" mode, the real part of the data is compare with the model.
        The data need to be phase calibrated.

Key: clip
        For planets, this parameter can be used to discard data for baselines
        that are significantly resolved. Data for a particular baseline will
        be discarded when the expected flux density on that baseline is
        less than the clip factor times the total flux density. The clip
        parameter takes on values between 0 to 1.0, with the default being 0
        (ie the default is to accept all data).

Key: device
        PGPLOT device to plot the model data as well as the visibility
        data. The default is to not produce a plot. No plot is produced
        in triple mode.

Key: options
        Extra processing options. Several can be given, separated by commas.
          noapply Do not apply the scale factor - just evaluate it.
          nospec Do not try to determine and correct the spectral index across
                 the band.
 
Revision: 1.15, 2014/06/05 03:49:06 UTC