A differencing simulation

A differencing simulation

Logged on 25/08/09 14:04:53

A very nice feature of example-sim.py (and MeqTrees in general) is the ability to stick a spigot into one column of the Measurement Set and subtract your predicted data from the existing data, writing the difference to another column of the MS. You will have already encountered this technique if you have read the 'SSSC1 and Calico' PURR log, but it's also very useful for simulation.

In this exercise we'll disable the E-Jones matrix, predict the visibilities and subtract them from the DATA column, which contains visibilities which were generated with the primary beam simulation included.

Click the 'TDL Options' button to bring up the compile time menu. DIsable the 'Use E Jones' option, and set 'Simulation mode:' to 'subtract from MS'. Click compile.

[If you examine the tree at this point you should hopefully see both spigots and sinks under the VisDataMux node.] S For the run time options make sure 'Input MS column' is set to 'DATA', and we'll write the differenced visibilities to the 'CORRECTED_DATA' column. Set up these options and click 'simulate MS'.

Data products

sssc30_compile_time_options_2.png

sssc30_compile_time_options_2.png