Advanced Gain Calibration Techniques in Radio Interferometry

TL;DR

This paper discusses advanced gain calibration methods in radio interferometry, emphasizing self-calibration techniques that improve image quality and sensitivity, especially at high frequencies with sparse calibrators.

Contribution

It provides a comprehensive overview of self-calibration methods, practical tips, and examples using ALMA data, including advanced phase transfer techniques for high-frequency observations.

Findings

Self-calibration improves image accuracy and sensitivity.

Examples demonstrate effective calibration in various observational contexts.

Advanced phase transfer techniques are crucial at high frequencies.

Abstract

In this lecture, we describe a number of advanced gain calibration techniques. In particular, self-calibration is an important tool in interferometric imaging at all wavelengths. It allows the observer to determine and remove residual phase and amplitude errors that remain in the data after normal calibration while simultaneously producing a more accurate and more sensitive image of the target source. We describe the basic technique of self-calibration and attempt to dispel some common misconceptions. We proceed to give a range of useful tips, and provide continuum, spectral line, and mosaic self-calibration examples using ALMA data. We also discuss fast switching and radiometric phase correction along with advanced phase transfer techniques that can become advantageous or even essential at high frequency where the density of sufficiently bright phase calibrators becomes sparse.