Linear map-making with LuSEE-Night

TL;DR

LuSEE-Night is a lunar far side radio telescope that uses linear map-making techniques to produce low-resolution sky maps in the 1-50 MHz range, effectively handling systematic uncertainties.

Contribution

This paper introduces a linear map-making approach using Wiener filtering for the LuSEE-Night radio telescope to produce sky maps while marginalizing systematic effects.

Findings

Able to produce ~5-degree resolution sky maps below 50 MHz

Systematic effects like beam uncertainty and gain fluctuations can be marginalized

Method demonstrates effective deconvolution of large sky areas from correlation data

Abstract

LuSEE-Night is a pathfinder radio telescope on the lunar far side employing four 3-m monopole antennas arranged as two horizontal cross pseudo-dipoles on a rotational stage and sensitive to the radio sky in the 1-50 MHz frequency band. LuSEE-Night measures the corresponding 16 correlation products as a function of frequency. While each antenna combination measures radiation coming from a large area of the sky, their aggregate information as a function of phase in the lunar cycle and rotational stage position can be deconvolved into a low-resolution map of the sky. We study this deconvolution using linear map-making based on the Wiener filter algorithm. We illustrate how systematic effects can be effectively marginalised over as contributions to the noise covariance and demonstrate this technique on beam knowledge uncertainty and gain fluctuations. With reasonable assumptions about instrument performance, we show that LuSEE-Night should be able to map the sub-50 MHz sky at a ~5-degree resolution.