We present the first results from the MALT-45 (Millimetre Astronomers Legacy Team - 45 GHz) Galactic Plane survey. We have observed 5 square-degrees ($l = 330 - 335$, $b = pm0.5$) for spectral lines in the 7 mm band (42-44 and 48-49 GHz), including $
text{CS}$ $(1-0)$, class I $text{CH}_3text{OH}$ masers in the $7(0,7)-6(1,6)$ $text{A}^{+}$ transition and $text{SiO}$ $(1-0)$ $v=0,1,2,3$. MALT-45 is the first unbiased, large-scale, sensitive spectral line survey in this frequency range. In this paper, we present data from the survey as well as a few intriguing results; rigorous analyses of these science cases are reserved for future publications. Across the survey region, we detected 77 class I $text{CH}_3text{OH}$ masers, of which 58 are new detections, along with many sites of thermal and maser $text{SiO}$ emission and thermal $text{CS}$. We found that 35 class I $text{CH}_3text{OH}$ masers were associated with the published locations of class II $text{CH}_3text{OH}$, $text{H}_2text{O}$ and $text{OH}$ masers but 42 have no known masers within 60 arcsec. We compared the MALT-45 $text{CS}$ with $text{NH}_3$ (1,1) to reveal regions of $text{CS}$ depletion and high opacity, as well as evolved star-forming regions with a high ratio of $text{CS}$ to $text{NH}_3$. All $text{SiO}$ masers are new detections, and appear to be associated with evolved stars from the $it{Spitzer}$ Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE). Generally, within $text{SiO}$ regions of multiple vibrational modes, the intensity decreases as $v=1,2,3$, but there are a few exceptions where $v=2$ is stronger than $v=1$.
We introduce the MALT-45 (Millimetre Astronomers 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 observati
onal 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.
