Precision Beam Mapping for 21cm Cosmology

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Understanding the epoch of early galaxy formation is a key objective of astronomy in the coming decade. This distant, early phase of the Universe is revealed by radio-wave emissions from hydrogen atoms. Detecting such emission is the goal of radio interferometer arrays. This project is an innovative method of calibrating one such experiment. Jacobs and collaborators will use a remote controlled drone octocopter to fly a calibration source over the array and directly measure its response. Preliminary results demonstrate that this approach is superior to more established methods. However, drone calibration has not yet been proven for entire arrays. This project is notable for student participation and the popularity that drone flights achieve in the public imagination. It will set a new and inexpensive standard for array calibration. This use of drones captivates students and the general public at outreach events and sets an example of the careful, methodical process of scientific investigation.This project supports the broad objective of understanding early galaxy formation by detecting redshifted 21cm hydrogen emission using radio telescope arrays. The Hydrogen Epoch of Reionization Array (HERA), supported by NSF in the Mid-Scale Innovations Program, is one such initiative. This project seeks to directly map the primary beams of HERA using a calibrated transmitter mounted to a computer controlled drone octocopter. Drone-based calibration of radio telescopes is gaining popularity, but the method is still experimental. This project is an outgrowth of a previous, successful award that demonstrated drone-based beam mapping at the Green Bank Observatory. Results of that work demonstrated comparable accuracy and superior beam coverage to other calibration methods. This project will extend the methodology previously done on a single antenna to an entire array.