October 5-9, 2014


P4.9 Direction Dependent Effects In Widefield Wideband Full Stokes Radio Imaging - A Challenge For The Next Generation Radio Telescope Surveys.

Preshanth Jagannathan (National Radio Astronomy Organization)

Sanjay Bhatanagar, Urvashi Rau, Russ Taylor

Synthesis imaging in radio astronomy is affected by instrumental and atmospheric effects which introduce direction-dependent(DD) gains.The antenna power pattern varies both as a function of time and frequency. The broad band time varying nature of the antenna power pattern when not corrected leads to gross errors in full stokes imaging and flux estimation. In this poster we explore the errors that arise in image deconvolution while not accounting for the time and frequency dependence of the antenna power pattern. Simulations were conducted with the wideband full stokes power pattern of the Very Large Array(VLA) antennas to demonstrate the level of errors arising from direction-dependent gains and their non-neglible impact on upcoming sky surveys such as the VLASS. Direction dependent corrections through hybrid projection algorithms are computationally expensive to perform. A highly parallel implementation through high performance computing architectures is the only feasible way of applying these corrections to the large data sizes of these upcoming surveys.

Mode of presentation: poster

Applicable ADASS XXIV theme category: Large surveys