Summary

Fit a single component source model to the uv-data. Three models are available: P=point; G=Gaussian; D=Disk. Fitting parameters can be held fixed. The results are given in the CASA log and placed in a components file. More information can be found about uvmodelfit here.

Parameter descriptions

vis

Name of input visibility file. Default: none. Examples: vis='ngc5921.ms'

field

Select data based on field id(s) or name(s). Default: '' (all). Examples: field='1'; field='0~2', field IDs inclusive from 0 to 2; field='3C*', all field names starting with 3C

spw

Select data based on spectral window. Default: '' (all). Examples: spw='1'; spw='<2' #spectral windows less than 2; spw='>1', spectral windows greater than 1

selectdata

Select a subset of the visibility using MSSelection. Default: False.  Examples: selectdata=True

timerange

Select data based on time range. Default = '' (all). Examples: timerange = 'YYYY/MM/DD/hh:mm:ss~YYYY/MM/DD/hh:mm:ss'

Further examples: timerange='09:14:0~09:54:0' yields the quoted time range; timerange='09:44:00' yields data within one integration of the specified time; timerange='>10:24:00' yields data after the specified time; timerange='09:44:00+00:13:00' yields data 13 minutes after the specified time

uvrange

Select data within uvrange (default units kilo-lambda). Default: '' (all). Examples: uvrange='0~1000klambda', uvrange from 0-1000 kilo-lambda; uvrange='>4klambda', uvranges greater than 4 kilo lambda; uvrange='0~1000km', uvrange in kilometers

antenna

Select data based on antenna/baseline. Default: '' (all).  Examples: antenna='5&6', baseline 5-6; antenna='5&6;7&8', baselines 5-6 and 7-8; antenna='5', all baselines with antenna 5; antenna='5,6', all baselines with antennas 5 and 6

scan

Select data based on scan number. Default: '' (all). Examples: scan='>3'

msselect

Optional data selection (field,spw,time,etc). Default:'' means select all.  Examples: msselect='FIELD_ID==0'; msselect='FIELD_ID IN [0,1,2]' means select fields 0,1 and 2; msselect='FIELD_ID <= 1' means select fields 0, 1; msselect='FIELD_ID==0 && ANTENNA1 IN [0] && ANTENNA2 IN [2:26]' means select field 0 and antennas 0 to 26, except antenna 1. Other msselect fields are: 'DATA_DESC_ID', 'SPECTRAL_WINDOW_ID', 'POLARIZATION_ID', 'SCAN_NUMBER', 'TIME', 'UVW'.

niter

Number of fitting iterations to execute. Default: 5. Examples: niter=20

comptype

Component model type. Default: 'P'. Options: 'P' (point source), 'G' (elliptical gaussian), 'D' (elliptical disk)

sourcepar

Starting guess for component parameters. Default: [1,0,0] (for comptype='P').

If comptype = 'P', then sourcepar = [flux,xoff,yoff], where flux = flux (Jy), xoff = offset east (arcsec), yoff = offset north (arcsec).

If comptype = 'G' or 'D', then sourcepar = [flux,xoff,yoff,majax,axrat,pos], where majax = FWHM along the major axis (arcsec), axrat < 1 is the ratio of minor to major axis, pos = position angle (deg)

varypar

Control which parameters to let vary in the fit. Default: [ ] (all vary). Examples: varypar=[False,True,True]

Examples with comptype, sourcepar, and varypar

Fit a point: comptype = 'P', sourcepar = [0.4,0.2,-0.3], varypar = [True,True,True]

Fit a circular Gaussian: comptype = 'G', sourcepar = [1.4,0.3,-0.2,0.3, 1, 0], varypar = [ True , True ,  True , True , False, False]

outfile

Optional output component list table. Default: ''. Examples: outfile='componentlist.cl'

How to get the output values: