HARP/ACSIS: A submillimetre spectral imaging system on the James Clerk Maxwell Telescope

TL;DR

The paper introduces HARP/ACSIS, a new submillimetre spectral imaging system on the JCMT, enabling rapid, high-resolution large-scale mapping for astrophysical research.

Contribution

It presents the design, capabilities, and advantages of the HARP/ACSIS system, including its high mapping speed and suitability for large-scale surveys.

Findings

Enables large-scale maps of 1 square degree in under 1 hour.

Provides high spatial and spectral resolution imaging.

Improves calibration and image quality over single-detector systems.

Abstract

This paper describes a new Heterodyne Array Receiver Programme (HARP) and Auto-Correlation Spectral Imaging System (ACSIS) that have recently been installed and commissioned on the James Clerk Maxwell Telescope (JCMT). The 16-element focal-plane array receiver, operating in the submillimetre from 325 to 375 GHz, offers high (three-dimensional) mapping speeds, along with significant improvements over single-detector counterparts in calibration and image quality. Receiver temperatures are $\sim$120 K across the whole band and system temperatures of $\sim$300K are reached routinely under good weather conditions. The system includes a single-sideband filter so these are SSB figures. Used in conjunction with ACSIS, the system can produce large-scale maps rapidly, in one or more frequency settings, at high spatial and spectral resolution. Fully-sampled maps of size 1 square degree can be observed in under 1 hour. The scientific need for array receivers arises from the requirement for programmes to study samples of objects of statistically significant size, in large-scale unbiased surveys of galactic and extra-galactic regions. Along with morphological information, the new spectral imaging system can be used to study the physical and chemical properties of regions of interest. Its three-dimensional imaging capabilities are critical for research into turbulence and dynamics. In addition, HARP/ACSIS will provide highly complementary science programmes to wide-field continuum studies, and produce the essential preparatory work for submillimetre interferometers such as the SMA and ALMA.