Western Australian antennas undergoing tests at NRAO
A second antenna array, the Murchison Widefield Array (MWA), is undergoing test runs at the National Radio Astronomy Observatory in Green Bank. This array will be installed at the Shire of Murchison in western Australia, an area that is also a dedicated quiet zone.
MIT Professor of Physics and Director of Kavli Institute for Astrophysics and Space Research Jacqueline Hewitt was in Green Bank last week working on the array, which is also attempting to collect information from the Big Bang.
ﾓThe idea is to measure Hydrogen structures very early in the history of the universe and to do that you need to do low frequency radio observations,ﾔ she said. ﾓThat is something that has never been done before and itﾒs actually a very difficult measurement to make. Itﾒs not clear as to the best way to do it, so right now weﾒre kind of building the exploratory instruments to figure out how to do this measurement.ﾔ
The array is being testing at the NRAO because it is the only National Radio Quiet Zone in the US.
Although the array is collecting the same information as the PAPER (Precision Array to Probe for the Epoch of Re-ionization) antennas, the MWA is a completely different design.
ﾓWeﾒre using different approaches to see what kind of approach works better,ﾔ Hewitt said. ﾓIﾒm working with Rich Bradley, based in Charlottesville, Virginia, and heﾒs developed some calibration techniques which work on any antenna, not just PAPER antennas. We decided to bring our antennas here and apply his techniques.ﾔ
Hewitt said the task of collecting low frequency data is very different that anything ever done.
ﾓPeople built low frequency radio antennas before but they were for measuring bright things like the sun which is very easy to see,ﾔ she explained. ﾓWeﾒre trying to measure very small signals coming from way back in the history of the universe. Itﾒs a difficult measurement.ﾔ
With the two arrays being tested in the same area, Hewitt said there is a possibility of creating an array utilizing both styles of antennas.
ﾓThe two kinds of antennas have different advantages,ﾔ she said. ﾓWe wonder if maybe a combined array will provide results. The PAPER antennas are very nice to calibrate, but these [MWA] have more collecting area.ﾔ
Hewitt said she hopes to operate the test antennas at Green Bank from her office at MIT, making it easier to collect data without leaving the university.
Some antennas are already on site in Western Australia and will grow to include 128 antennas when the test run is finished. Hewitt said all the actual measurements and official data will be collected there.