Particularly at the shorter wavelengths, the ALMA will need to do mosaic observing to cover large fields of view. Along with the mosaic pointing, there will need to be total power maps to fill in the interferometric short spacings and produce complete images. It is well known that this is best done with a single antenna that is two to three times the diameter of the interferometer antennas. However, that will not be possible for ALMA; there are no 24m - 36m antennas available that will work well to 0.35mm wavelength. As long as a mosaic of pointings is employed in the interferometry, a single antenna map made with one of the interferometer antennas will suffice in principle. This is rarely done, largely because the interferometer antennas are not usually equipped to do it. This capability must be in place for the ALMA antennas. How it is best done may be studied with the prototype antennas.
View a pdf version of ALMA Memo #454.
Last modified: 2003-04-21
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