Create a Component List for Selfcal

If you want to selfcal on a point source (or a list of point sources) with known position, you may create your own model component list. To do so, you can use the tools like this:

cl.addcomponent(flux=1.25, fluxunit='mJy', polarization='Stokes',
dir='J2000 19h30m00 15d00m00', shape='gaussian', majoraxis='10arcsec',
minoraxis='6arcsec', positionangle='0deg', freq='1.25GHz',
spectrumtype='spectral index', index=-0.8)
###you can add more components if you wish by calling addcomponent repeatedly with different params

##save it to disk
cl.rename('my_1_component.cl')
cl.close()

## write the model into the MODEL_DATA column of your data ('myms')
ft(vis='myms', complist='my_1_component.cl')

Then proceed with the gaincal as in normal selfcal routines.