A Study on Non-coplanar Baseline Effects for Mingantu Spectral Radioheliograph

TL;DR

This paper provides a comprehensive quantitative analysis of the w-term effects in solar radio imaging with the MingantU SpEctral RadioHeliograph, highlighting its significance for high-resolution solar observations.

Contribution

It systematically investigates the baseline variations and w-term effects over a year, emphasizing their impact on solar radio imaging accuracy.

Findings

W-term significantly affects high-resolution solar imaging.

Baseline variations correlate with w-term fluctuations.

Simulations show image distortion due to w-term effects.

Abstract

As a dedicated solar radioheliograph, the MingantU SpEctral RadioHeliograph (MUSER) has a maximum baseline of more than 3000 meters and a frequency range of 400 MHz -- 15 GHz. According to the classical radio interferometry theory, the non-coplanar baseline effect (i.e., w-term effect) would be considered and calibrated for such a radio instrument. However, little previous literature made the qualitative or quantitative analyses on w-term effects of solar radioheliograph in-depth. This study proposes a complete quantitative analysis of w-term effects for the MUSER. After a brief introduction of the MUSER, we systematically investigate the baseline variations over a year and analyze the corresponding variations of w-term. We further studied the effects of the w-term in the imaging for the specified extended source, i.e., the Sun. We discussed the possible effects of the w-term, such as image distortion and so on. The simulated results show that the w-term is an essential and unavoidable issue for solar radio imaging with high spatial resolution.