Improved Measurement of the Spectral Index of the Diffuse Radio Background Between 90 and 190 MHz

Understand

We report absolutely calibrated measurements of diffuse radio emission between 90 and 190 MHz from the Experiment to Detect the Global EoR Signature (EDGES).

• EDGES employs a wide beam zenith-pointing dipole antenna centred on a declination of -26.7$^\circ$.
• We measure the sky brightness temperature as a function of frequency averaged over the EDGES beam from 211 nights of data acquired from July 2015 to March 2016.
• We derive the spectral index, $\beta$, as a function of local sidereal time (LST) and find -2.60 > $\beta$ > -2.62 $\pm$0.02 between 0 and 12 h LST.