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MMA Memo #169

Atmospheric Coherence Times at Chajnantor

M.A. Holdaway

April 21, 1997

Keywords: coherence, decorrelation, phase stability, site testing

We investigate the distribution of atmospheric coherence times for long baselines and the fraction of time a given baseline will be phase stable during the months of best phase stability. The coherence times set a lower limit to the time over which the MMA electronics must allow stable integration. It is probable that radiometric phase compensation will further increase the requirements on the MMA electronics. The best quartile coherence time (at 90\% sensitivity) at 100~GHz is about 4~minutes, while best quartile coherence time at 650~GHz is only 8~s.

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Last modified: 09 December, 1999