PLATFORM DEFORMATION PHASE CORRECTION FOR THE AMiBA-13 COPLANAR INTERFEROMETER

Journal Article · Mon May 20 00:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/769/1/71· OSTI ID:22126607

Liao, Yu-Wei; Lin, Kai-Yang; Huang, Yau-De; Ho, Paul T. P.; Chen, Ming-Tang; Locutus Huang, Chih-Wei; Koch, Patrick M.; Nishioka, Hiroaki; Umetsu, Keiichi; Han, Chih-Chiang; Li, Chao-Te; Martin-Cocher, Pierre; Oshiro, Peter ^[1]; Proty Wu, Jiun-Huei; Cheng, Tai-An; Fu, Szu-Yuan; Wang, Fu-Cheng ^[2]; Liu, Guo-Chin ^[3]; Molnar, Sandor M. ^[4]; Chang, Yu-Yen ^[5]

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1. Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China)
2. Department of Physics, Institute of Astrophysics, and Center for Theoretical Sciences, National Taiwan University, Taipei 10617, Taiwan (China)
3. Department of Physics, Tamkang University, 251-37 Tamsui, New Taipei City, Taiwan (China)
4. Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei 10617, Taiwan (China)
5. Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)

We present a new way to solve the platform deformation problem of coplanar interferometers. The platform of a coplanar interferometer can be deformed due to driving forces and gravity. A deformed platform will induce extra components into the geometric delay of each baseline and change the phases of observed visibilities. The reconstructed images will also be diluted due to the errors of the phases. The platform deformations of The Yuan-Tseh Lee Array for Microwave Background Anisotropy (AMiBA) were modeled based on photogrammetry data with about 20 mount pointing positions. We then used the differential optical pointing error between two optical telescopes to fit the model parameters in the entire horizontal coordinate space. With the platform deformation model, we can predict the errors of the geometric phase delays due to platform deformation with a given azimuth and elevation of the targets and calibrators. After correcting the phases of the radio point sources in the AMiBA interferometric data, we recover 50%-70% flux loss due to phase errors. This allows us to restore more than 90% of a source flux. The method outlined in this work is not only applicable to the correction of deformation for other coplanar telescopes but also to single-dish telescopes with deformation problems. This work also forms the basis of the upcoming science results of AMiBA-13.

• OSTI ID: 22126607
• Journal Information: Astrophysical Journal, Vol. 769, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ANISOTROPY
CORRECTIONS
DEFORMATION
ERRORS
GRAVITATION
INTERFEROMETERS
LEVELS
LOSSES
MICROWAVE RADIATION
POINT SOURCES
SIMULATION
SPACE DEPENDENCE
TELESCOPES
VISIBILITY