1.7 Separation of spectral windows

This transformation is done as part of the regridms transformation although it can be done without any frame transformation. The mstransform task can separate the spectral windows into a regular grid of channels specified by the user using the parameter nspw. This is a new feature in CASA 4.1.0+ and can be applied in many use-cases.

If nspw is greater than 1, the input spws will be separated into the given number. Note that internally, the framework will first combine the input spws to take gaps and overlaps into account. It will divide the total number of channels in the combined spw by nspw to create the separated spws. If the total number of channels is not divisible by nspw, it will set the remainder channels to 0 in the last spw. See the following example:

    mstransform('uid.ms', outputvis='myout.ms', spw='0:0~49', regridms=True, nspw=3)
  
  It will create 3 output spws, each with 17 channels. The last channel in the last spw will be set to 0.

If nchan is set, it will refer to the number of channels to have in each separated spw.