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Proceedings Paper

ALMA fast switching phase calibration on long baselines
Author(s): Yoshiharu Asaki; Satoki Matsushita; Ryohei Kawabe; Ed Fomalont; Denis Barkats; Stuartt Corder
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Paper Abstract

We present results of feasibility studies of Atacama Large Millimeter/submillimeter Array (ALMA) interferom- eter phase calibration scheme combined with the Fast Switching (FS) phase referencing and the Water Vapor Radiometer (WVR) phase correction (FS+WVR phase correction). With FS scheme, ALMA antennas observe a scientific target source and a nearby calibrator by turn very quickly. Because interferometer phase errors of the target due to the water vapor contents commonly exist in those of the calibrator, the target phase is corrected with the calibrator phase. We have demonstrated the FS+WVR phase correction for ALMA with baselines up to 2.7 km for various switching cycle times and separations between sources. For instance, in the case of sources with the 1° separation, root-mean-square phases of the target were reduced from 300 to 40 microns in path length for 1 km baselines, and the target interferometer phases could be stabilized to an ALMA specification requirement level for the interferometer phase stability. We also analytically evaluated the root-mean-square phase corrected with the FS+WVR phase correction to predict the performance as a function of the separation and switching cycle time.

Paper Details

Date Published: 22 July 2014
PDF: 12 pages
Proc. SPIE 9145, Ground-based and Airborne Telescopes V, 91454K (22 July 2014); doi: 10.1117/12.2055824
Show Author Affiliations
Yoshiharu Asaki, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (Japan)
Japan Aerospace Exploration Agency (Japan)
Satoki Matsushita, Academia Sinica Institute of Astronomy and Astrophysics (Taiwan)
Ryohei Kawabe, National Astronomical Observatory of Japan (Japan)
Ed Fomalont, National Radio Astronomy Observatory (United States)
Joint ALMA Observatory (Chile)
Denis Barkats, Joint ALMA Observatory (Chile)
Stuartt Corder, Joint ALMA Observatory (Chile)

Published in SPIE Proceedings Vol. 9145:
Ground-based and Airborne Telescopes V
Larry M. Stepp; Roberto Gilmozzi; Helen J. Hall, Editor(s)

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