A MEASUREMENT OF THE SUNYAEV-ZELDOVICH EFFECT IN THE COMA CLUSTER OF GALAXIES

We report the detection of the Sunyaev-Zel'dovich effect in the Coma c luster of galaxies with the 5.5 m telescope at the Owens Valley Radio Observatory. The measured decrement of the temperature of the cosmic m icrowave background is Delta T-0,T-obs,obs -270 +/- 29 mu K After corr ecting for the effect of discrete radio sources and applying current m odels for the X-ray atmosphere of the cluster, we calculate the peak o f the effect to be Delta T-0(0) = -505 +/- 92 mu K. Using the same X-r ay models, and assuming spherical symmetry for the gas atmosphere, we derive a Hubble constant of H-0= 71(-25)(+30) km s(-1) Mpc(-1). This i s the first detection of the Sunyaev-Zel'dovich effect in a nearby clu ster of galaxies.