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27th of October 2017
EDGES - an Experiment to Detect the Global EoR Signature
by Judd Bowman (Arizona State University)
The Experiment to Detect the Global Epoch-of-Reionisaton (EoR) Signature (EDGES) is a radio spectrometer operated at the Murchison Radio-astronomy Observatory by Arizona State University and MIT Haystack Observatory. The experiment aims to detect the global redshifted 21 cm signature of neutral hydrogen gas in the early Universe due to the formation of the first stars and subsequent reionization of the intergalactic medium. It measures the sky-averaged spectrum below 200 MHz using two instruments. Each instrument consists of a zenith-pointed broadband dipole antenna with smooth beam properties and a receiver that has been precisely calibrated to 0.1% absolute accuracy and better than 0.01% relative accuracy across an octave of bandwidth.

Photo caption: Cheap trick! A used brekkie juice bottle protects a capacitive tuning plate on top of the EDGES low-band antenna from condensation and rain water. Excess moisture in narrow gap can change the tuning of the antenna, adversely affecting the sensitive cosmology measurements.

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