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ALMA MEMO #427
Antenna Position Calibration
Radio Astronomy laboratory, University of California, Berkeley
Keywords: Antenna Position, Calibration
This memo summarizes the antenna position calibration used at Hat
Creek, and discusses its application to the CARMA and ALMA telescopes.
Observations of quasars over wide range of HA and DEC
provide data from which the antenna positions are determined. If the
antenna positions are in error by many wavelengths, 2pi phase
ambiguities may make this process difficult, especially when the
atmospheric phase coherence is poor on long baselines. In this case the
antenna positions can be first determined from the phase difference
between the sidebands in a double sideband system, or across
a wideband single sideband. In addition to the antenna
positions, there may be axis offsets on the antennas which can be
fitted from the quasar data or measured mechanically. These offsets
should be stable and not change when the antennas are moved.
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Last modified: 2002-05-29