A maximum-likelihood approach to removing radio sources from observations of the Sunyaev-Zel'dovich effect, with application to Abell 611

We describe a maximum-likelihood technique for the removal of contaminating radio sources from interferometric observations of the Sunyaev-Zel'dovich (SZ) effect. This technique, based on a simultaneous fit for the radio sources and extended SZ emission, is also compared to techniques previously applied to Ryle Telescope observations and is found to be robust. The technique is then applied to new observations of the cluster Abell 611, and a decrement of -540 +/- 125 μJy beam^-1 is found. This is combined with a ROSAT HRI image and a published ASCA temperature to give an H₀ estimate of 52⁺²⁴_-16 km s^-1 Mpc^-1.