Measurement of the Sunyaev-Zeldovich Effect in A2142 and A2256
Session 125 -- Structure of Clusters of Galaxies
Oral presentation, Saturday, January 15, 2:15-3:45, Crystal Forum Room (Crystal City Marriott)

## [125.02] Measurement of the Sunyaev-Zeldovich Effect in A2142 and A2256

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We present results from the Cosmic Microwave Background program at the Caltech Owens Valley Radio Observatory. Dual-horn switched HEMT receivers on the 5m telescope ($\nu=32$ GHz, $7\pmin4$ FWHM, $22\pmin15$ switching) and the 40m telescope ($\nu=19$ GHz, $2'$ FWHM, $7\pmin15$ switching) were used to look for anisotropy in the microwave background radiation and to measure the Sunyaev-Zeldovich (SZ) effect in a sample of clusters of galaxies.
Several clusters selected from an X-ray flux-limited sample were observed on the 5m and 40m telescopes, including the clusters A399, A2142, and A2256. The preliminary results from these clusters is discussed. The SZ effect was detected in A2142 ($\sim 0.5$ mK) and A2256 ($\sim 0.3$ mK) at the levels expected from the available X-Ray data. Using a grid'' of cluster models, the SZ measurements and the X-Ray data are used to determine the values of the Hubble constant $H_0$. We also present new results from the microwave background anisotropy experiments on the 40m and 5m telescopes.