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Configure the spectral setup

In Cycle 2 you have three main options for the spectral setup, which are described in some detail in the following subsections. Depending on the spectral setup selected you will specify a frequency on sky or in the rest frame of the source(s). A conversion between rest and sky frequency is performed by the OT using the source velocity specified in Step 3.4. Of course, the frequencies on sky of the proposed observations must fall within one of the ALMA bands offered (Bands 3, 4, 6, 7, 8 and 9 for Cycle 2). You can visualise your chosen spectral setup using the spectral viewer in the Visualisation section of the Spectral tab. By default, the spectral viewer will show the ALMA bands available, as well as the atmospheric transmission curve. You can let the OT automatically choose the water vapour column density as appropriate for the ALMA band selected, or change it manually for visualization purposes only. Once you provide information on your spectral setup, it will also show the Local Oscillator (LO1) frequency and the sidebands as well as your spectral window(s). You can move around the spectral windows (e.g. to avoid strong atmospheric lines) by changing the input frequency. Moving the sidebands by dragging the LO in the spectral editor does not change the spectral setup, but is for visualisation purposes only. For this reason, the sidebands will automatically ``spring back'' to any valid spectral setup actually specified after you move them in the viewer. You can zoom in/out by left/right-clicking when the cursor becomes a magnifying glass symbol or using the Zoom to Band and Reset buttons. Panning (i.e. horizontally shifting the frequency range viewed) is achieved by dragging the green sliding bars that appear when moving the cursor near the frequency axes, or using Pan to Line. For a practical demonstration of the spectral editor please refer to OT video tutorial 2: The Spectral Setup.

Figure 3.3: Visualisation of continuum observations in the spectral editor pane.
Image fig4

Select the Polarization Products desired using the appropriate radio buttons in the Spectral Type section. In Cycle 2 both XX (Single) and Dual polarizations are available for all correlator setups and bands offered. You will generally select XX polarization only when attempting to achieve the highest possible spectral resolution. Full polarization is now offered in Bands 3, 6 and 7 for continuum measurements at standard frequencies and single pointings of well-centred targets filling no more than 1/3 of the 12-m Array primary beam.



Subsections
next up previous contents
Next: Single Continuum Up: Proposal creation and submission Previous: Add the source information   Contents
The ALMA OT Team, 2014 May 21