Robert Lucas 
November 6, 1997
Keywords: antenna pointing, pointing calibration, anomalous refraction, wind
We investigate the accuracy of pointing measurements for proposed versions of the LSA/MMA array. We show that in interferometric mode, the sensitivity of pointing measurements is governed, expressed as a fraction of the beam width, by the product of the surface of one antenna by the square root of the number of antennas, and thus does not scale like the total collecting power. Frequent pointing calibration to the accuracy needed for mosaics should be possible, relaxing the need for pointing stability on time scales longer than 30 min. In that respect we have checked the pointing performance of the Plateau de Bure antennas; the pointing accuracy in September weather is nearly always limited by atmospheric seeing (independently of operating frequency).
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