AAS 197, January 2001
Session 55. The Cosmic Microwave Background
Oral, Tuesday, January 9, 2001, 10:30am-12:00noon, Golden Ballroom

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[55.02] Polarization Observations with the Cosmic Background Imager

J. K. Cartwright, S. Padin, T. J. Pearson, A. C. S. Readhead, M. C. Shepherd (California Institute of Technology), G. B. Taylor (National Radio Astronomy Observatory)

The linear polarization of the Cosmic Microwave Background Radiation is a fundamental prediction of the standard model. We report a limit on the polarization of the CMBR for l~660. This limit was obtained with the Cosmic Background Imager, a 13 element interferometer which operates in the 26-36 GHz band from a site at 5000m in northern Chile. The array consists of 90-cm Cassegrain antennas mounted on a single, fully steerable platform; this platform can be rotated about the optical axis to facilitate polarization observations. The CBI employs single mode circularly polarized receivers, of which 12 are configured for LCP and one is configured for RCP. The 12 cross polarized baselines sample multipoles from l~600 to l~3500. The instrumental polarization of the CBI was calibrated with observations of 3C279, a bright polarized source which is unresolved by the CBI. Because the centimeter flux of 3C279 is variable, it was monitored twice per month for 8 months in '00 with the VLA at 22 and 43 GHz. These observations also established the stability of the polarization characteristics of the CBI. This work was made possible by NSF grant AST-9802989

The author(s) of this abstract have provided an email address for comments about the abstract: jkc@astro.caltech.edu

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