Application of continuous corrections in widefield imaging obtained with the IDGCAL calibration method

Abstract

Image Domain Gridding (IDG) is an efficient method to evaluate A-projection, a method for correcting for direction dependent effects (DDEs) in radio astronomical imaging. The corrections i.e. the A-terms need to be estimated from the observed data through calibration. IDG-CAL is a calibration algorithm that employs the IDG algorithm in an iterative fashion to estimate A-terms directly. Initial results for low order A-terms are promising, however for deeper images higher order A-terms are needed. Here two improvements to IDG-CAL are proposed to 1) reduce the computational cost of A-terms described by more parameters and 2) optimize the set of basis functions describing the A-terms based on a stochastic model of the gain variations and the model image.

7 pages, 4 figures, SPIE Astronomical Telescopes + Instrumentation 2026, SPIE Paper Number 14153-92