Spectral information in CASA - ESO

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Spectral Transformation in the viewer and plotms viewer and plotms offer spectral transformation options: viewer: plotms: a) in the spectral profiler b) in the “axis label properties” item of the Data Display Options in the “Trans” tab All three are pure transformations of the displayed spectral axis! No software Doppler-tracking of visibilities is performed! I.e. only good for (nearly) time-independent transformations of spectra like, e.g., LSRK→BARY. D. Petry, Spectral information in CASA, February 2013 14
Spectral averaging with split When regridding, cvel and clean with with interpolation (cvel also offers fftshift) Good when keeping roughly the same resolution. When increasing the channel width by more than factor 2, i.e. for spectral averaging, better use the split task with parameter width. Example: split(vis='myvis.ms', outputvis='out.ms', width=3) will average to 3 x original resolution. If ref. frame trafo required: first do split, then cvel/clean. split also offers time-averaging via the timebin parameter. Careful with time-averaging before ref. frame trafo! D. Petry, Spectral information in CASA, February 2013 15
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Spectral information in CASA - ESO

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