MALT-45: A 7 mm survey of the southern Galaxy - I. Techniques and
  spectral line data
  We present the first results from the MALT-45 (Millimetre Astronomer's 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 $\text{CH}_3\text{OH}$ 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 $\text{CH}_3\text{OH}$ 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 $\text{CH}_3\text{OH}$ masers
were associated with the published locations of class II
$\text{CH}_3\text{OH}$, $\text{H}_2\text{O}$ 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 $v=1$.
