Pilot Observations for MALT-45: A Galactic Plane Survey at 7mm

TL;DR

The paper presents initial pilot observations of the MALT-45 Galactic plane survey at 7mm, demonstrating instrumentation capabilities and detecting various molecular lines and masers in targeted regions.

Contribution

It introduces the MALT-45 survey and reports pilot results, showcasing the use of new instrumentation and observational techniques for Galactic plane molecular line studies.

Findings

Detected widespread CS (1-0) emission.

Identified eight Class I CH3OH masers at 44 GHz.

Detected SiO masers and radio recombination lines.

Abstract

We introduce the MALT-45 (Millimetre Astronomer's Legacy Team - 45 GHz) Galactic plane survey and describe pilot survey results with the Australia Telescope Compact Array (ATCA). The pilot survey was conducted to test the instrumentation and observational technique of MALT-45, before commencing the full survey. We mapped two half-square degree regions within the southern Galactic plane around the G333 giant molecular cloud, using fast mosaic mapping. Using the new Compact Array Broadband Backend (CABB) on the ATCA, we were able to observe two 2048 MHz spectral windows, centred on frequencies 43.2 and 48.2 GHz. Although only a coarse spectral resolution of around 7 km/s was available to us, we detect widespread, extended emission in the CS (1-0) ground state transition. We also detect eight Class I CH3OH masers at 44 GHz and three SiO masers in vibrationally excited (1-0) transitions. We also detect the H53a radio recombination line, non-vibrationally excited SiO (1-0) and emission in the CH3OH 1_1-0_0 A+ line.