Effect of gain and phase errors on SKA1-low imaging quality from 50-600 MHz

TL;DR

This study uses simulations to evaluate how gain and phase errors affect SKA1-low's imaging quality across 50-600 MHz, revealing frequency-dependent noise behaviors and residual sidelobe noise reduction.

Contribution

It provides the first comprehensive analysis of gain and phase error impacts on SKA1-low imaging quality over an extended frequency range, including noise level estimations.

Findings

Residual sidelobe noise decreases with frequency, by a factor of ~5 from 50 to 100 MHz.

RMS deviations between ideal and error-affected images decrease as frequency increases.

Thermal noise limit is between ~0.3 to 10 μJy, depending on integration time and frequency.

Abstract

Simulations of SKA1-low were performed to estimate the noise level in images produced by the telescope over a frequency range 50-600 MHz, which extends the 50-350 MHz range of the current baseline design. The root-mean-square (RMS) deviation between images produced by an ideal, error-free SKA1-low and those produced by SKA1-low with varying levels of uncorrelated gain and phase errors was simulated. The residual in-field and sidelobe noise levels were assessed. It was found that the RMS deviations decreased as the frequency increased. The residual sidelobe noise decreased by a factor of ~5 from 50 to 100 MHz, and continued to decrease at higher frequencies, attributable to wider strong sidelobes and brighter sources at lower frequencies. The thermal noise limit is found to range between ~10 - 0.3 $\mu$Jy and is reached after ~100-100 000 hrs integration, depending on observation frequency, with the shortest integration time required at ~100 MHz.