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