Dipole projection

This log demonstrates the effects of dipole projection. It uses the WSRT_le.MS ("low elevation") Measurement Set from Oleg, and the sky model is generated using the Siamese.OMS.gridded_sky module.

The first part shows images created without dipole projection taken into account, and the second part shows images with the L-Jones matrix included.

This uses the Cattery/Siamese/example-sim.py script. Compile-time and run-time options were set up as in the screenshots below.

The output MS column was set to MODEL_DATA before pressing 'Simulate MS'.

The imaging options were set up as in the screenshot before pressing 'Make a dirty image' - note that the full Stokes parameters were selected.

The image shows that there is no polarization leakage, since the sky model contained unpolarized sources, and they only show up in the Stokes I image. The simulated Stokes Q, U and V images are all blank.

Now I'll try to simulate the measurement set with dipole projection (the L-Jones) included. Opened 'TDL Options' and set up the compile-time settings as in the screenshot below. Note that 'Use L Jones' is now selected, as is 'Per-source projection'.

'Simulate MS' was then selected from the run-time options.

To image the new measurement set, I opened the 'TDL Exec' window, and made a dirty image with the same settings as in the previous step (see screenshot).

Instrumental polarization is now present, as can be seen from the non-zero fluxes in the Q and U images.