1 The MSTransform framework

The mstransform task has been designed to be a single place for many common operations used in the pre-imaging steps of interferometric data reduction. It does almost everything done by hanningsmooth, partition, split and cvel, and more. The task has the following capabilities, which can be done independently or combined. Except for split which is the default state of the task, each transformation has a boolean parameter to switch it on or off.

1. Split into a new MS using data selection parameters.
2. Partition into a new Multi-MS using data selection parameters.
3. Combination of spectral windows.
4. Channel averaging using channelized FLAG and WEIGHT/SIGMA_SPECTRUM (if present) as the weights.
5. Hanning smoothing.
6. Reference frame transformation, similar to cvel.
7. Separation of spectral windows, which does not have an independent boolean switch, but it can be independently applied when regridms=True and the nspw parameter is set to > 1.
8. Time averaging using channelized FLAG and WEIGHT/SIGMA_SPECTRUM (if present) as the weights.

Mapping of parameters between split-mstransform and cvel-mstransform.

    split               mstransform                                      Comments
 -----------------------------------------------------------------------------------------------------
    width               chanaverage=True, chanbin                        perform channel averaging
    timebin             timeaverage=True, timebin                        perform time averaging
    combine             timeaverage=True, timespan                       time averaging with time spanning
    keepflags           keepflags                                        keep or drop flags in output

    cvel                mstransform                                      Comments
 -----------------------------------------------------------------------------------------------------
    hanning             hanning=True                                     Hanning smoothing
    other parameters    combinespws=True, regridms=True, cvel parameter  regrid the MS
    ---                 regridms=True, nspw                              does not exist in cvel

Documentation for the task and tool can be found in: Task Documentation Tool Documentation