The micro-Jansky radio source population at 5 GHz

A field of area 0.000015 sr with unprecedented sensitivity was imaged in order to compile a complete catalog of 62 microJy radio sources with a peak flux density at 5 GHz greater than 16 microJy at 8 arsec resoluton and a typical positional accuracy of 0.2 arcsec. An analysis of the image intensity distribution below the detection limit indicates that the slope of the integral count between 2 and 16 microJy is -1.3 + or - 0.2. Thus, the slope of the count between 2 and 1000 microJy is nearly constant and close to the Euclidean value of -1.5. It is found that the average angular size of the sources appears to increase at flux densities below 60 microJy. Fifteen of the 16 radio sources between 60 and 800 mJy have extended emission with a median size of 4 arcsec, often in addition to a radio core. Nearly all sources have optical counterparts brighter than about 27.5 mag, and most weak radio sources identified with faint blue galaxies with a median magnitude of about 23.