The radio/optical catalog of the SSA 13 field

We present a 1.4 GHz catalog of 810 radio sources (560 sources in the complete sample) found in the SSA 13 field (R.A. = 13^h12^m, decl. = 42°38′). The 1.4 GHz radio image was obtained from a 91 hr VLA integration with an rms noise level of 4.82 μJy beam^-1 at the field center. Optical images in the R band (6300 Å) and z band (9200 Å) with 3 σ detection magnitudes of 26.1 and 24.9, respectively, were obtained from three observing nights on the 8 m Subaru Telescope. We find that 88% ± 2% of the radio sources are identified with an optical counterpart. There is significantly more reddening for the optical counterparts that are fainter than 24 mag, probably caused by the somewhat larger red-shifts of these faint galaxies. The radio and optical parameters are tabulated, and source morphologies are displayed by radio contours overlaid on optical false-color images. The brightness distributions show a wealth of complexity and are classified into a small number of categories. About one-third of the radio sources are larger than 1″.2, and their orientation is often similar to that of the associated galaxy or binary galaxy system. Radio emission is sometimes located outside of the nuclear regions of the galaxy. The density of sources in the SSA 13 field above 75 μJy is 0.40 arcmin^-2, with a slope of -2.43 in the differential counts. This source density is somewhat higher than that in the Hubble Deep Field North. The radio spectral index may steepen for sources below 75 μJy and is consistent with the difference in the slope of the source counts observed between 1.4 and 8.4 GHz. We estimate that at most 40% of the microjansky radio sources are dominated by AGN processes, while the remainder are mostly the consequence of star formation and associated supernova activity.