Outputs

The primary output product of MeqSilhouette is a CASA Measurement Set containing the complex visibilities, with all the user-requested corruptions applied to the data. The Measurement Set v2 specification can be found here. The tables and subtables in the MS are filled as follows:

  • The value of ms_datacolumn in the input JSON file must correspond to an existing column in the MAIN table. This column is filled with the corrupted complex visibilities.

  • The MODEL_DATA column is filled with uncorrupted visibilities. It is recommended not to set ms_datacolumn=’MODEL_DATA’ so that the uncorrupted visibilities are available to the user for later inspection.

  • The SIGMA column is filled with the standard deviation of the baseline-based complex visibilities computed using the SEFD. If mulltiple frequency channels are present, then SIGMA_SPECTRUM is also filled with these values.

  • The WEIGHT column is filled with inverse-variance weighting with the variance computed using the SIGMA values. If mulltiple frequency channels are present, then WEIGHT_SPECTRUM is also filled with these values.

  • The ANTENNA subtable is the same as the input antenna table pointed to by ms_antenna_table.

Optionally, there a few other outputs that MeqSilhouette can generate for recording the synthetic data generation process and verifying the contents of the MS.

  • The numerical values of all the Jones matrices are saved as numpy arrays.

  • A number of plots illustrating the properties of the complex visibilities and the various effects applied to them.

  • A preliminary image of the simulated data.

  • Export the MS into UVFITS format, for compatibility with other calibration packages such as eht-imaging and AIPS.