The faintest radio source yet: EVLA observations of the gravitational
  lens SDSS J1004+4112
  We present new radio observations of the large-separation
gravitationally-lensed quasar SDSS J1004+4112, taken in a total of 6 hours of
observations with the Extended Very Large Array (EVLA). The maps reach a
thermal noise level of approximately 7microJy. We detect four of the five
lensed images at the 30-65microJy level, representing a source of intrinsic
flux density, after allowing for lensing magnification, of about 2microJy,
intrinsically probably the faintest radio source yet detected. This reinforces
the utility of gravitational lensing in potentially allowing us to study
nanoJy-level sources before the advent of the SKA. In an optical observation
taken three months after the radio observation, image C is the brightest image,
whereas the radio map shows flux density ratios consistent with previous
optical observations. Future observations separated by a time delay will give
the intrinsic flux ratios of the images in this source.
