Basic Information on uvfmeas

Task: uvfmeas
Purpose: Calculate the fluxes of a point source at the phase
Categories: uv analysis

        UVFMEAS plots averaged spectra of a visibility dataset. It is
        used to measure the spectral behaviour of a continuum source,
        and can perform high order polynomial fits to the data. In this
        way, a flux density at a particular frequency can be more
        accurately determined. Multiple sets at different frequencies
        can be simultaneously plotted, allowing you to make a global
        fit over a wider range of frequencies, which may be more accurate.

Key: vis
        The name of the input uv data sets. Several can be given (wild
        cards are supported). No default.

Key: select
        The normal uv selection commands. The default is plot everything.

Key: line
        The normal uv linetype in the form:
          line,nchan,start,width,step
        The default is all channels (or all wide channels if there are no
        spectral channels).

Key: stokes
        The Stokes/polarization types to be plotted. The default is to
        plot those polarizations present in the input files. Stokes
        parameters will not however be overplot on each other; only one
        polarization will be plotted at a time.

Key: hann
        Hanning smoothing width (an odd integer).  Smoothing is
        applied after averaging. Default is 1 (no Hanning smoothing).

Key: offset
        An offset (in arcsec) to shift the data. Positive values result in
        the data center being shifted to the North and East. Two values
        should be given, being the shift in the RA and DEC directions.
        The default is 0,0 (i.e. no shift).

Key: order
        The order of the highest term in the polynomial fit this task
        should make to the spectrum it plots.

Key: options
        This gives extra processing options. Several options can be given,
        each separated by commas. They may be abbreviated to the minimum
        needed to avoid ambiguity. Possible options are:
           'nocal'       Do not apply the gains file. By default, UVSPEC
                         applies the gains file in copying the data.
           'nopass'      Do not apply bandpass corrections. By default,
                         UVSPEC corrects for the bandpass shape if the
                         required information is available.
           'nopol'       Do not apply polarization corrections. By default
                         UVSPEC corrects for polarization cross-talk.
           'log'         Do the spectral fitting in log space. By default
                         the fitting is done with the raw values. The plots
                         will still show the raw values when this option
                         is used. This option will be overridden, and a
                         warning displayed, if there are negative raw
                         values that make it impossible to do a log fit.
           'plotvec'     Use the vector average values for the plot and
                         the fit. By default, the scalar average values
                         are used.
           'uvhist'      Plot the uvdistance vs spectrally-corrected
                         amplitudes after plotting the spectrum and fit.
                         This will also show the histogram fit to the
                         data used to estimate the usability of the source
                         as a calibrator.
           'plotfit'     Plot a user-specified fit over the spectrum. The
                         coefficients of the fit are given with the fitp
                         parameter.
           'machine'     Output the fit coefficients on a single line,
                         separated by spaces, suitable for parsing by
                         another program.
           'mfflux'      Output the fit coefficients in a way that can be
                         input as the flux parameter in mfcal. Only really
                         works for order=1 (linear fit).
           'malpha'      Output the alpha coefficients on a single line,
                         separated by spaces, suitable for parsing by
                         another program.
           'reshist'     Plot a histogram of the normalised residuals
                         from the fit.
           'nolines'     Do not plot the vector and scalar average lines.

Key: yrange
        The min and max range along the y axis of the plots. The default
        is to autoscale.

Key: device
        PGPLOT plot device/type. No default.

Key: nxy
        Number of plots in the x and y directions. The default is
        determined from the number of plots that are requested.

Key: log
        Log file into which the averaged data are dumped. If the option
        'uvhist' is specified, the log file will contain the bin values:
        uvdist val Np
        Otherwise, the log file will contain the spectral values and fit:
        freq fluxdensity fluxfit

Key: fitp
        The coefficients of a fit that you would like this task to
        overplot onto the spectrum. The coefficients must relate to the
        same type of fit (ie. log space or raw values) as the main fit
        would use.

Key: feval
        A frequency (in GHz) at which to evaluate the fit, and output
        the flux density in Jy.
 
Revision: 1.21, 2014/09/22 01:33:27 UTC