The H I Parkes All Sky Survey: southern observations, calibration and robust imaging

TLDR

HIPASS data acquisition began at the Parkes 64‑m telescope in February 1997 and finished in March 2000. The paper aims to describe the HIPASS survey observations and the calibration and imaging techniques employed. The authors use statistically robust processing algorithms, including a median‑gridding technique that replaces the mean estimator, to mitigate interference and enhance imaging of point sources. HIPASS is the deepest southern H I survey, detecting emission out to 170 h75⁻¹ Mpc with a typical rms noise of 13.3 mJy.

Abstract

The acquisition of H i Parkes All Sky Survey (HIPASS) southern sky data commenced at the Australia Telescope National Facility's Parkes 64-m telescope in 1997 February, and was completed in 2000 March. HIPASS is the deepest H i survey yet of the sky south of declination +2°, and is sensitive to emission out to 170 h75−1 Mpc. The characteristic root mean square noise in the survey images is 13.3 mJy. This paper describes the survey observations, which comprise 23 020 eight-degree scans of 9-min duration, and details the techniques used to calibrate and image the data. The processing algorithms are successfully designed to be statistically robust to the presence of interference signals, and are particular to imaging point (or nearly point) sources. Specifically, a major improvement in image quality is obtained by designing a median-gridding algorithm which uses the median estimator in place of the mean estimator.