A Variable Source

Many sources are variable on the time scales of a typical observation. This challenge deals with such a source. It's based on the source from SSSC1 but has the following characteristics:

1. A relatively constant unpolarised quiesent level of emission.

2. Strong highly (cicularly) polarised periodic bursts every 2 hours.

A modified LSM module is provided below. This allows the addition of variable characterisics to components of the LSM model. An additional "Variable" option appears in the LSM sky model section in which you can specify a file containing these characteristics. The variablity this simulates is periodic bursting rather than sin like periodicity. To use it, it's useful to create your own copy of the Cattery and replace the file Mewo/LSM.py with the attached file. Set the environment variable MEQTREES_CATTERY_PATH to point to your private cattery.

The same template Measurement as used in SSSC1 can be used here. When we use the Meow LSM option there is the additional options to specify if the source is variable and we can specify a file which gives the source parameters. This will produce a source with a constant unpolarised 10Jy flux and periodic (2hr) bursts of circular 100Jy emission.

If we image the dataset we can see it is dominated by the variable component.