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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: 1.25, 2019/05/07 04:06:41 UTC
Generated by miriad@atnf.csiro.au on 13 Sep 2019