1. The MWA is located at Boolardy Station in outback Western Australia, 800 kilometers to the 

north of Perth. It is located there because it is a very remote location, so there are not a 

lot of human-generated radio signals around, so it's a good place for a radio telescope (the 

use of which is obviously hampered if there are a lot of intense human-generated signals 

around).

2. The Epoch of Reionization was an epoch in the history of the universe in which matter in the 

universe was reionized; it was the 2nd phase transition of gas. At first, the universe was 

filled with ionized gas; it was very opaque. Afterwards, it became neutral and homogenous and 

transparent; after that came the Epoch of Reionization, which marked the beginning of formation 

of galaxies and quasars.

3. A power spectrum measures the dynamics of "bubbles" of ionized gas during the epoch of 

reionization. Through Fourier analysis of these dynamics one can determine the 

expansion/compression oscillations of bubbles of matter.

4. HERA stands for Hydrogen Epoch of Reionization Array. It is the next generation of radio 

telescopes, following the MWA, and it is to be built collaboratively, using experience gained 

from the MWA and the PAPER telescope arrays. It will provide some of the first images of 

large-scale hydrogen ion structure.