Limits of noise and confusion in the MWA GLEAM year 1 survey

TL;DR

This paper investigates the noise and confusion limits in the GLEAM survey, revealing sidelobe confusion as the dominant noise source, which suggests potential for data processing improvements to enhance survey sensitivity.

Contribution

It provides a detailed analysis of noise and confusion contributions in the GLEAM survey, highlighting the dominance of sidelobe confusion across frequencies.

Findings

Sidelobe confusion dominates over system noise and classical confusion.

Understanding noise sources is crucial for optimizing low-frequency radio surveys.

Data processing improvements could significantly reduce noise levels.

Abstract

The GaLactic and Extragalactic All-sky MWA survey (GLEAM) is a new relatively low resolution, contiguous 72-231 MHz survey of the entire sky south of declination +25 deg. In this paper, we outline one approach to determine the relative contribution of system noise, classical confusion and sidelobe confusion in GLEAM images. An understanding of the noise and confusion properties of GLEAM is essential if we are to fully exploit GLEAM data and improve the design of future low-frequency surveys. Our early results indicate that sidelobe confusion dominates over the entire frequency range, implying that enhancements in data processing have the potential to further reduce the noise.