The case of 3C326: VLA 74 MHz observations during a geomagnetic storm

TL;DR

This paper discusses advanced calibration techniques for low-frequency radio observations, demonstrating their application on VLA data of 3C326 during a geomagnetic storm to improve data quality.

Contribution

It compares various calibration methods and showcases their effectiveness on real data under challenging ionospheric conditions.

Findings

Successful application of calibration methods during geomagnetic disturbances

Improved data quality at 74 MHz with advanced calibration techniques

Insights into ionospheric effects on low-frequency radio observations

Abstract

Reaching the thermal noise at low frequencies with the next generation of instruments (e.g. SKA, LOFAR etc.) is going to be a challenge. It requires the development of more advanced techniques of calibration compared to those used from the traditional radio astronomy until now. This revolution has slowly started, from self-cal, going through field based correction and SPAM up to the formulation and application of a general Measurement Equation. We will describe and compare the several approaches of calibration used so far to reduce low frequency data. We will present some results of a 74 MHz VLA observation in exceptional ionospheric conditions of the giant radio galaxy 3C326 for which some of these methods have been successfully applied.