HERA

The HERA project (https://reionization.org) has recently received US$9.5M from the US National Science Foundation for a three-year effort to build out the array to 240 dishes in the compact core. The HERA partners also contribute resources towards that goal, particularly with support from SKA South Africa. Partner institutions in the collaboration are Arizona State University, Brown University, University of California Berkeley, University of California Los Angeles, University of Cambridge, Massachusetts Institute of Technology, National Radio Astronomy Observatory, University of Pennsylvania, Scuola Normale Superiore de Pisa, SKA-South Africa and the University of Washington. Additional collaborators are Cal Poly Pomona, Imperial College, Harvard-Smithsonian Center for Astrophysics, University of KwaZulu Natal, Rhodes University and University of Western Cape.

The US$9.5M funds the US partners as well as SKA South Africa to purchase most of the equipment. The US funding provides primarily for the post-doctoral researchers and graduate students that will be providing the analysis that will take the data through to the Epoch of Reionization (EOR) science. It also provides for some management and design. The team held its annual workshop in Cambridge, MA in October to start planning on the new scope, as shown below.

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HERA annual workshop team photo in Cambridge, MA.

HERA is currently commissioning the first 19 elements while construction on the next 18 elements is well underway to make the first 37 elements of the hexagonal-packed array. The current efforts also incorporate many of the original PAPER elements, which are well understood. The PAPER elements are in one of several sub-arrays: (1) 19 elements that are in the same configuration as the 19 HERA elements, (2) a redundant grid sub-array, which represents the last PAPER grid configuration, (3) an imaging sub-array, where they have been moved into a semi-random/semi-circle configuration, and (4) a polarisation test sub-array, where some of the grid antennas have been rotated by 45 degrees. Comparative studies are underway.

One current emphasis has been the software infrastructure and monitor and control, which are needed to handle the much larger scope of array. All data transactions are handled by a process called the Librarian, which does what any good librarian does and makes sure data is properly checked out, logged and checked in at the proper branch. A high-level functional overview is shown below, with the software efforts in the shaded area.

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Functional system overview. The primary software elements are shaded.

The three element array in Cambridge, UK, is largely complete and the first testing is underway, which is focused on matching a very detailed electromagnetic model to comprehensive measurements. The test array will also allow testing on feed options, which will be upgraded for the bigger build-out. This will include drone testing for beam patterns.

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HERA test array at Cavendish Laboratory’s Lord’s Bridge location near Cambridge, UK.


Report provided by David de boer, University of Berkeley, HERA Project Manager