Mosaicing with interferometers: An efficient algorithm for imaging and image plane corrections

The imaging dynamic range of an aperture synthesis telescope for mosaicing and for fields with significant flux throughout the antenna primary beams can be limited by the knowledge of the individual primary beams projected on the sky. For high dynamic range imaging of such fields, one requires an accurate measurement of the shape of the primary beams and the pointing offsets as a function of time. The effect of antenna pointing errors remain separable in the visibility domain. With at least two, well separated sources along the RA and Dec axis each to constrain the solutions, it is possible to solve for these errors in an antenna based fashion in the visibility domain. Here we describe an algorithm to solve for these errors using a model for the sky brightness distribution. For a typical L-band eVLA simulation with typical pointing errors for the VLA antennas, the RMS noise can be reduced by a factor of similar to 10 using this algorithm. The improvement in the image fidelity is even larger.