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A partial work around for this situation is to use the two ATCA frequency bands to observe in adjacent somewhat overlapping windows, and using the same bandwidths and channel counts for the two windows. With the ATCA this is possible with some correlator configurations when observing with bandwidths of 16, 64 or 128 MHz. Miriad allows you to stitch these two spectral windows together in a reasonably straightforward fashion (although some quirks do become apparent). In so doing, it handles any overlap region between the two windows in a sensible fashion. The steps to achieve this are as follows:
edge
parameter is the easiest way to flag these channels.
Task uvlin processes each frequency band separately. You will want to give some thought when setting the range of channels to use in the fitting of the continuum. If the spectral of interest in near the edge of the individual spectra, you will want to set the channels to use in uvlin's fitting process carefully. You may wish to use a zeroth order fit, and just fit using channels at the edges away from the overlap region. Alternatively you may wish to run uvlin after the two spectra are stitched together instead. Some experimentation (and certainly thought) will be required.
Note that
when handling multiple bands, both Miriad's line
and uvlin's
chans
parmaters number channels consecutively from 1 to the total
number of simultaneous channels. The distinction between simultaneous bands is
ignored in this numbering. But when fitting to the continuum, the
boundaries between bands act as a break point.
Miriad manager