A Technique for Primary Beam Calibration of Drift-Scanning, Wide-Field Antenna Elements

TL;DR

This paper introduces a novel calibration technique for wide-field, drift-scanning antenna beams that uses crossing points and rotational symmetry to model the beam and source fluxes with minimal calibrator sources.

Contribution

It presents a new method leveraging crossing points and rotational symmetry to calibrate primary beams without extensive source spectra or standard routines.

Findings

Successfully applied to PAPER data and simulations.

Achieves beam calibration with only a few tens of sources.

Circumvents the need for many well-characterized calibrators.

Abstract

We present a new technique for calibrating the primary beam of a wide-field, drift-scanning antenna element. Drift-scan observing is not compatible with standard beam calibration routines, and the situation is further complicated by difficult-to-parametrize beam shapes and, at low frequencies, the sparsity of accurate source spectra to use as calibrators. We overcome these challenges by building up an interrelated network of source "crossing points" -- locations where the primary beam is sampled by multiple sources. Using the single assumption that a beam has 180 degree rotational symmetry, we can achieve significant beam coverage with only a few tens of sources. The resulting network of crossing points allows us to solve for both a beam model and source flux densities referenced to a single calibrator source, circumventing the need for a large sample of well-characterized calibrators. We illustrate the method with actual and simulated observations from the Precision Array for Probing the Epoch of Reionization (PAPER).