Correlation Calibration: A Hybrid Calibration Tool for Next-Generation Radio Interferometers

Precise and accurate calibration has historically been, and remains, one of the chief concerns for all applications of radio interferometry. Correctly characterizing and removing direction-independent gains is a necessary first step for producing science-quality data, as it establishes an absolute flux scale and ensures accurate relative phases between antennas. Many current and next-generation radio interferometers adopt a drift-scan approach, where array elements cannot be steered. In this regime the traditional approach of calibrating to known sources is much more challenging, and novel calibration techniques are needed for reliable calibration. This need is exacerbated by the growing interest in 21-cm cosmology, where exquisite calibration solutions are required to enable analysts to recover the faint cosmological signal lurking behind the overwhelmingly bright astrophysical foregrounds.