The Angular Two-Point Correlation Function for the FIRST Radio Survey

The FIRST (Faint Images of the Radio Sky at Twenty centimeters) survey now covers 1550 deg^2^ of sky, where 07^h^16 <~ α <~ 17^h^40 and 28.3^deg^ <~ δ <~ 42^deg^. This yields a catalog of 138,665 sources above the survey threshold of 1 mJy, about one-third of which are in double-lobed and multicomponent sources. We have used these data to obtain the first high-significance measurement of the two-point angular correlation for a deep radio sample. We find that the correlation function between 0.02^deg^ and 2^deg^ is well fitted by a power law of the form Aθ^gamma^, where A ~ 3 x 10^-3^ and γ ~ -1.1. On small scales (θ < 0.2^deg^), double and multicomponent sources are shown to have a larger clustering amplitude than that of the whole sample. Sources with flux densities below 2 mJy are found to have a shallower slope than that obtained for the whole sample, consistent with there being a significant contribution from starbursting galaxies at these faint fluxes. The cross-correlation of radio sources and Abell clusters is determined. A preliminary approach to inferring spatial information is outlined.