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Paper: 22 GHz Water Vapor Radiometry at the VLA
Volume: 217, Imaging at Radio Through Submillimeter Wavelengths
Page: 338
Authors: Butler, B. J.
Abstract: As part of the VLA Upgrade Project (Bastian & Bridle 1995), new low-noise, high-efficiency K-band (18-26 GHz) receiver systems are being constructed and placed on the antennas of the VLA. Water vapor radiometry (WVR) systems have been designed to be placed alongside these new receivers, in order to attempt to measure and correct for atmospheric phase fluctuations at the higher frequencies of operation of the VLA. These WVR systems are similar to Dave Woody's in design (Marvel & Woody 1998), with minor modifications. The radiation is received through the astronomy receiver in its dewar, then filtered into 3 channels. The intent is to provide the data measured by the WVRs along with the visibility data to post-processing software (AIPS or aips++) in order to correct for atmospheric phase fluctuations in the visibilities. I will present several issues related to WVR at the VLA, including center frequency and width of the WVR channels, effects of liquid water on phase retrieval, and divergence of WVR beam from astronomical receiver beam in the atmosphere.
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