Precise measurement of the absolute radio sky brightness from 60 MHz to 350 MHz

This precision measurement of the brightness of the diffuse sky from 60 MHz to 350 MHz can be used to improve the absolute calibration of all-sky maps and global sky models at long radio wavelengths [1]. The primary data are measurements of antenna temperature in kelvin versus frequency and local sidereal time (LST), with radio frequency interference masked and with corrections applied for receiver noise waves, bandpass, and impedance mismatch between antenna and receiver. Measurements were collected on 2024 October 23 at Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory in Australia (latitude −27.059 34°, longitude 116.479 561°, height 320.0 m) and cover the LST range between 20 h and 4 h. Frequency-dependent antenna beam patterns are included in machine readable format for the purpose of relating antenna temperature to sky brightness. Ref. [1] gives an example of using these data to derive offset and scale factor corrections for the improved global sky model (GSM) published in 2017 [2].

[1] McKay, L. et al. (2025) “Precise measurement of the absolute sky brightness at 60–350 MHz.” doi:10.48550/arXiv.2509.11846

[2] Zheng, H. et al. (2017) “An improved model of diffuse Galactic radio emission from 10 MHz to 5 THz.” Mon. Not. R. Astron. Soc. 464, 3486–3497. doi:10.1093/mnras/stw2525