1.4 Combination of spectral windows

Task mstransform can combine spectral windows independently or with a reference frame transformation. When combinespws is set to True, the task will combine all the selected spectral windows into one. The index of the output spw will be 0. When there are overlapping channels, they will be averaged to form one output channel.

    mstransform('uid.ms', outputvis='myout.ms', datacolumn='data', spw='1,3,5', combinespws=True)

1.4.1 Handling spectral windows with different sensitivities

Whenever the data to be combined has different EXPOSURE values in the spectral windows, mstransform will use the WEIGHT_SPECTRUM for the combination. If WEIGHT_SPECTRUM is not available, it will use the values from the WEIGHT column. Each output channel is calculated using the following equation:

outputChannel_j = SUM(inputChannel_i*contributionFraction_i*inputWeightSpectrum_i) 
                --------------------------------------------------------------------
                        SUM(contributionFraction_i*inputWeightSpectrum_i)

where:
    contributionFraction_i are geometrical factors to take into account any gaps or overlaps in the spws.