You can add spectral windows by selecting spectral lines using theALMA Spectral Line Picker (click on Select Lines to Observe... ). Lines selected using this will automatically beentered into the spectral window table when the tool is closed. TheSpectral Lines Selection tool is discussed in detail inSection 5.6 . Alternatively, click the Add button to define a spectral window and enter the centre frequency (inthe rest frame of the source).
In the spectral window table the basic spectral settings should be specified:
In choosing your spectral window frequencies, it is important torealise that there are restrictions on where a spectral window can belocated. The fundamental restriction is that all spectral windows mustfit into the two sidebands of the receiver (for bands 3-10). Thewidths and separations of these vary from receiver to receiver, butthey are graphically illustrated using the Visual Spectral Editor andwe recommend that this be used when defining spectral windows. Also,there is a peculiarity when observing in ALMA bands 3-8: it iscurrently only possible to put two spectral windows in each sideband,or all of them in one of the sidebands. Again, this restriction willeventually disappear. The OT knows about all of these restrictions andwill complain if you define an illegal spectral window setup.
The allowed correlator modes are also subject to restrictions. Not allcorrelator modes have yet been tested and so the OT restricts yourchoice to those that have been made available for Cycle 0 of EarlyScience. Another restriction for this cycle is that each spectralwindow has to have the same bandwidth and channel spacing! This willalso change in future cycles, but for now, if you wish to performhigh-resolution/narrow bandwidth spectral line observations and alsorequire a continuum measurement, this should be defined in a separateScience Goal.