Search

This study uses archival high frequency continuum data to expand the search for Hypercompact HII regions and determine the conditions at which they appear, as this stage high mass star formation is short-lived and rare. We use 23 GHz continuum data taken towards methanol masers, which are an excellent signpost for very young embedded high-mass protostars. We have searched for high-frequency, optically thick radio sources to identify HC HII region candidates. The data cover 128 fields that include 141 methanol masers identified by the Methanol Multibeam (MMB) survey. We have detected 68 high-frequency radio sources and conducted a multi-wavelength analysis to determine their nature. This has identified 49 HII regions, 47 of which are embedded in dense clumps fourteen of which do not have a 5 GHz radio counterpart. We have identified 13 methanol maser sites that are coincident with radio sources that have a steep positive spectral index. The majority of these are not detected in the mid-infrared and have been classified as protostellar or young stellar objects in the literature and we therefore consider to be good HC HII region candidates, however, further work and higher resolution data are needed to confirm these candidates.

We report the detection of ammonia masers in the non-metastable (6, 3), (7, 5) and (6, 5) transitions, the latter is the first unambiguous maser detection of that transition ever made. Our observations include the first VLBI detection of ammonia maser emission, which allowed effective constrain of the (6, 5) maser brightness temperature. The masers were detected towards G358.931-0.030, a site of 6.7-GHz class~II methanol maser emission that was recently reported to be undergoing a period of flaring activity. These ammonia masers appear to be flaring contemporaneously with the class~II methanol masers during the accretion burst event of G358.931-0.030. This newly detected site of ammonia maser emission is only the twelfth such site discovered in the Milky Way. We also report the results of an investigation into the maser pumping conditions, for all three detected masing transitions, through radiative transfer calculations constrained by our observational data. These calculations support the hypothesis that the ammonia (6, 5) maser transition is excited through high colour temperature infrared emission, with the (6, 5) and (7, 5) transition line-ratio implying dust temperatures >400K. Additionally, we detect significant linearly polarised emission from the ammonia (6, 3) maser line. Alongside our observational and radiative transfer calculation results, we also report newly derived rest frequencies for the ammonia (6, 3) and (6, 5) transitions., Comment: Accepted into MNRAS 2023 April 24. 13 pages, 5 figures, 3 tables

We present the full data release for the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH), a sensitive, unbiased single-dish survey of the Southern Galactic Plane in all four ground-state transitions of the OH radical at 1612, 1665, 1667 and 1720 MHz. The survey covers the inner Galactic Plane, Central Molecular Zone and Galactic Centre over the range $|b|<$ 2$^{\circ}$, 332$^{\circ}$ $< l <$ 10$^{\circ}$, with a small extension between 2$^{\circ}$ $< b <$ 6$^{\circ}$, 358$^{\circ}$ $< l <$ 4$^{\circ}$. SPLASH is the most sensitive large-scale survey of OH to-date, reaching a characteristic root-mean-square sensitivity of $\sim15$ mK for an effective velocity resolution of $\sim0.9$ km/s. The spectral line datacubes are optimised for the analysis of extended, quasi-thermal OH, but also contain numerous maser sources, which have been confirmed interferometrically and published elsewhere. We also present radio continuum images at 1612, 1666 and 1720 MHz. Based on initial comparisons with $^{12}$CO(J=1-0), we find that OH rarely extends outside CO cloud boundaries in our data, but suggest that large variations in CO-to-OH brightness temperature ratios may reflect differences in the total gas column density traced by each. Column density estimation in the complex, continuum-bright Inner Galaxy is a challenge, and we demonstrate how failure to appropriately model sub-beam structure and the line-of-sight source distribution can lead to order-of-magnitude errors. Anomalous excitation of the 1612 and 1720 MHz satellite lines is ubiquitous in the inner Galaxy, but is disabled by line overlap in and around the Central Molecular Zone., Comment: Main paper: 22 pages, 15 figures. Online-only material (appended to ArXiv PDF): 11 pages, 3 figure sets. Accepted to MNRAS. Survey data is available from: https://docs.datacentral.org.au/splash/

We present the most sensitive and detailed view of the neutral hydrogen (HI) emission associated with the Small Magellanic Cloud (SMC), through the combination of data from the Australian Square Kilometre Array Pathfinder (ASKAP) and Parkes (Murriyang), as part of the Galactic Australian Square Kilometre Array Pathfinder (GASKAP) pilot survey. These GASKAP-HI pilot observations, for the first time, reveal HI in the SMC on similar physical scales as other important tracers of the interstellar medium, such as molecular gas and dust. The resultant image cube possesses an rms noise level of 1.1 K (1.6 mJy/beam) per 0.98 km s$^{-1}$ spectral channel with an angular resolution of 30$''$ ($\sim$10 pc). We discuss the calibration scheme and the custom imaging pipeline that utilizes a joint deconvolution approach, efficiently distributed across a computing cluster, to accurately recover the emission extending across the entire $\sim$25 deg$^2$ field-of-view. We provide an overview of the data products and characterize several aspects including the noise properties as a function of angular resolution and the represented spatial scales by deriving the global transfer function over the full spectral range. A preliminary spatial power spectrum analysis on individual spectral channels reveals that the power-law nature of the density distribution extends down to scales of 10 pc. We highlight the scientific potential of these data by comparing the properties of an outflowing high velocity cloud with previous ASKAP+Parkes HI test observations., Comment: Accepted for publication in PASA, 34 pages, 18 figures, 5 tables

We have used catalogues from several Galactic plane surveys and dedicated observations to investigate the relationship between various maser species and Galactic star forming clumps, as identified by the ATLASGAL survey. The maser transitions of interest are the 6.7 & 12.2 GHz methanol masers, 22.2 GHz water masers, and the masers emitting in the four ground-state hyperfine structure transitions of hydroxyl. We find clump association rates for the water, hydroxyl and methanol masers to be 56, 39 and 82 per cent respectively, within the Galactic longitude range of 60{\deg} > $l$ > -60{\deg}. We investigate the differences in physical parameters between maser associated clumps and the full ATLASGAL sample, and find that clumps coincident with maser emission are more compact with increased densities and luminosities. However, we find the physical conditions within the clumps are similar for the different maser species. A volume density threshold of $n$(H$_{2}$) > 10$^{4.1}$ cm$^{-3}$ for the 6.7 GHz methanol maser found in our previous study is shown to be consistent across for all maser species investigated. We find limits that are required for the production of maser emission to be 500 L$_{\odot}$ and 6 M$_{\odot}$ respectively. The evolutionary phase of maser associated clumps is investigated using the L/M ratio of clumps coincident with maser emission, and these have similar L/M ranges (~10$^{0.2}$ - 10$^{2.7}$ L$_{\odot}$/M$_{\odot}$) regardless of the associated transitions. This implies that the conditions required for the production of maser emission only occur during a relatively narrow period during a star's evolution. Lower limits of the statistical lifetimes for each maser species are derived, ranging from ~0.4 - 2 x 10$^{4}$ yrs and are in good agreement with the "straw man" evolutionary model previously presented., Comment: Accepted for publication in the Monthly Notices of the Royal Astronomical Society, 17 pages, 14 figures, 5 tables

We present a study of the association between class I methanol masers and cold dust clumps from the ATLASGAL survey. It was found that almost 100% of class I methanol masers are associated with objects listed in the ATLASGAL compact source catalog. We find a statistically significant difference in the flux density, luminosity, number and column density and temperature distributions of ATLASGAL sources associated with 95/44 GHz methanol masers compared with those ATLASGAL sources devoid of 95 GHz methanol masers. The masers tend to arise in clumps with higher densities, luminosities and temperatures compared with both the full sample of the ATLASGAL clumps, as well as the sample of ATLASGAL sources that were cross-matched with positions previously searched for methanol masers but with no detections. Comparison between the peak position of ATLASGAL clumps and the interferometric positions of the associated class I and II methanol masers reveals that class I masers are generally located at larger physical distances from the peak submillimetre emission than class II masers. We conclude that the tight association between ATLASGAL sources and class I methanol masers may be used as a link toward understanding the conditions of the pumping of these masers and evolutionary stages at which they appear., Comment: Accepted to the Astronomical Journal, 14 pages, 7 figures

The Methanol MultiBeam survey (MMB) provides the most complete sample of Galactic massive young stellar objects (MYSOs) hosting 6.7GHz class II methanol masers. We characterise the properties of these maser sources using dust emission detected by the Herschel Infrared Galactic Plane Survey (Hi-GAL) to assess their evolutionary state. Associating 731 (73%) of MMB sources with compact emission at four Hi-GAL wavelengths, we derive clump properties and define the requirements of a MYSO to host a 6.7GHz maser. The median far-infrared (FIR) mass and luminosity are 630M$_{\odot}$ and 2500L$_{\odot}$ for sources on the near side of Galactic centre and 3200M$_{\odot}$ and 10000L$_{\odot}$ for more distant sources. The median luminosity-to-mass ratio is similar for both at $\sim$4.2L$_{\odot}/$M$_{\odot}$. We identify an apparent minimum 70$\mu$m luminosity required to sustain a methanol maser of a given luminosity (with $L_{70} \propto L_{6.7}^{0.6}$). The maser host clumps have higher mass and higher FIR luminosities than the general Galactic population of protostellar MYSOs. Using principal component analysis, we find 896 protostellar clumps satisfy the requirements to host a methanol maser but lack a detection in the MMB. Finding a 70$\mu$m flux density deficiency in these objects, we favour the scenario in which these objects are evolved beyond the age where a luminous 6.7GHz maser can be sustained. Finally, segregation by association with secondary maser species identifies evolutionary differences within the population of 6.7GHz sources., Comment: Accepted for publication in MNRAS, 30 pages, 28 figures + 2 appendices (2 pages, 3 figures)

From targeted observations of ground-state OH masers towards 702 Multibeam (MMB) survey 6.7-GHz methanol masers, between Galactic longitudes 186$^{\circ}$ through the Galactic centre to 20$^{\circ}$, made as part of the `MAGMO' project, we present the physical and polarisation properties of the 1720-MHz OH maser transition, including the identification of Zeeman pairs. We present 10 new and 23 previously catalogued 1720-MHz OH maser sources detected towards star formation regions. In addition, we also detected 16 1720-MHz OH masers associated with supernova remnants and two sites of diffuse OH emission. Towards the 33 star formation masers, we identify 44 Zeeman pairs, implying magnetic field strengths ranging from $-$11.4 to $+$13.2 mG, and a median magnetic field strength of $|B_{LOS}|$ $\sim$ 6 mG. With limited statistics, we present the in-situ magnetic field orientation of the masers and the Galactic magnetic field distribution revealed by the 1720-MHz transition. We also examine the association statistics of 1720-MHz OH SFR masers with other ground-state OH masers, excited-state OH masers, class I and class II methanol masers and water masers, and compare maser positions with mid-infrared images of the parent star forming regions. Of the 33 1720-MHz star formation masers, ten are offset from their central exciting sources, and appear to be associated with outflow activity.

We report the detection of new 12.178, 12.229, 20.347, and 23.121 GHz methanol masers in the massive star-forming region G358.93-0.03, which are flaring on similarly short timescales (days) as the 6.668 GHz methanol masers also associated with this source. The brightest 12.178 GHz channel increased by a factor of over 700 in just 50 d. The masers found in the 12.229 and 20.347 GHz methanol transitions are the first ever reported and this is only the fourth object to exhibit associated 23.121 GHz methanol masers. The 12.178 GHz methanol maser emission appears to have a higher flux density than that of the 6.668 GHz emission, which is unusual. No associated near-infrared flare counterpart was found, suggesting that the energy source of the flare is deeply embedded., Comment: 9 pages, 3 figures, 2 tables, Published in MNRAS

We have constructed the largest sample of dust-associated class II 6.7 GHz methanol masers yet obtained. New measurements from the the Methanol MultiBeam (MMB) Survey were combined with the 870 $\mu$m APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) and the 850 $\mu$m JCMT Plane Survey (JPS). Together with two previous studies we have now identified the host clumps for 958 methanol masers across the Galactic Plane, covering approximately 99% of the MMB catalogue and increasing the known sample of dust-associated masers by over 30%. We investigate correlations between the physical properties of the clumps and masers using distances and luminosities drawn from the literature. Clumps hosting methanol masers are significantly more compact and have higher volume densities than the general population of clumps. We determine a minimum volume density threshold of $n$(H$_2$) $\geq 10^4$ cm$^{-3}$ for the efficient formation of intermediate- and high-mass stars. We find 6.7 GHz methanol masers are associated with a distinct part of the evolutionary process ($L_{\rm bol}$/$M_{\rm fwhm}$ ratios of between 10$^{0.6}$ and 10$^{2.2}$) and have well defined turning on and termination points. We estimate the lower limit for the mass of embedded objects to be $\geq$ 6 M$_{\odot}$ and the statistical lifetime of the methanol maser stage to be $\sim$ 3.3$\times$10$^{4}$ yrs. This suggests that methanol masers are indeed reliable tracers of high mass star formation, and indicates that the evolutionary period traced by this marker is relatively rapid., Comment: Accepted for publication in the Monthly Notices of the Royal Astronomical Society, 20 pages, 23 figures, 6 tables

We present the unambiguous discovery of six new class II methanol maser transitions, three of which are torsionally excited (vt=1). The newly discovered 6.18-GHz 17_-2 -> 18_-3 E (vt=1), 7.68-GHz 12_4 -> 13_3 A- (vt=0), 7.83-GHz 12_4 -> 13_3 A+ (vt = 0), 20.9-GHz 10_1 -> 11_2 A+ (vt=1), 44.9-GHz 2_0 -> 3_1 E (vt=1) and 45.8-GHz 9_3 -> 10_2 E (vt=0) methanol masers were detected towards G358.931-0.030, where the known 6.68-GHz maser has recently been reported to be undergoing a period flaring. The detection of the vt=1 torsionally excited lines corroborates one of the missing puzzle pieces in class II maser pumping, but the intensity of the detected emission provides an additional challenge, especially in the case of the very highly excited 6.18-GHz line. Together with the newly detected vt=0 lines, these observations provide significant new information which can be utilised to improve class II methanol maser modelling. We additionally present detections of 6.68-, 19.9-, 23.1- and 37.7-GHz class II masers, as well as 36.2- and 44.1-GHz class I methanol masers, and provide upper limits for the 38.3- and 38.5-GHz class II lines. Near simultaneous Australia Telescope Compact Array (ATCA) observations confirm that all 10 of the class II methanol maser detections are co-spatial to ~0.2 arcsec, which is within the uncertainty of the observations. We find significant levels of linearly polarised emission in the 6.18-, 6.67-, 7.68-, 7.83-, 20.9-, 37.7-, 44.9- and 45.8-GHz transitions, and low levels of circular polarisation in the 6.68-, 37.7- and 45.8-GHz transitions., Comment: ApJL accepted 15 April 2019

The Australia Telescope Compact Array (ATCA) participated in a number of survey programs to search for and image common class I methanol masers (at 36 and 44 GHz) with high angular resolution. In this paper, we discuss spatial and velocity distributions revealed by these surveys. In particular, the number of maser regions is found to fall off exponentially with the linear distance from the associated young stellar object traced by the 6.7-GHz maser, and the scale of this distribution is 263+/-15 milliparsecs. Although this relationship still needs to be understood in the context of the broader field, it can be utilised to estimate the distance using methanol masers only. This new technique has been analysed to understand its limitations and future potential. It turned out, it can be very successful to resolve the ambiguity in kinematic distances, but, in the current form, is much less accurate (than the kinematic method) if used on its own., Comment: 4 pages, 1 figure, to appear in proceedings of IAU Symposium 336 "Astrophysical Masers: Unlocking the Mysteries of the Universe", Editors: A. Tarchi, M. J. Reid & P. Castangia

We have compared the occurrence of 6.7-GHz and 12.2-GHz methanol masers with 22-GHz water masers and 6035-MHz excited-state OH masers in the 100 square degree region of the southern Galactic plane common to the Methanol Multibeam (MMB) and H2O southern Galactic Plane surveys (HOPS). We find the most populous star formation species to be 6.7-GHz methanol, followed by water, then 12.2-GHz and, finally, excited-state OH masers. We present association statistics, flux density (and luminosity where appropriate) and velocity range distributions across the largest, fully surveyed portion of the Galactic plane for four of the most common types of masers found in the vicinity of star formation regions. Comparison of the occurrence of the four maser types with far-infrared dust temperatures shows that sources exhibiting excited-state OH maser emission are warmer than sources showing any of the other three maser types. We further find that sources exhibiting both 6.7-GHz and 12.2-GHz methanol masers are warmer than sources exhibiting just 6.7-GHz methanol maser emission. These findings are consistent with previously made suggestions that both OH and 12.2-GHz methanol masers generally trace a later stage of star formation compared to other common maser types., Comment: 16 pages, 12 figures, accepted MNRAS

The H2O Southern Galactic Plane Survey (HOPS) has mapped 100 square degrees of the Galactic plane for water masers and thermal molecular line emission using the 22-m Mopra telescope. We describe the automated spectral-line fitting pipelines used to determine the properties of emission detected in HOPS datacubes, and use these to derive the physical and kinematic properties of gas in the survey. A combination of the angular resolution, sensitivity, velocity resolution and high critical density of lines targeted make the HOPS data cubes ideally suited to finding precursor clouds to the most massive and dense stellar clusters in the Galaxy. We compile a list of the most massive HOPS ammonia regions and investigate whether any may be young massive cluster progenitor gas clouds. HOPS is also ideally suited to trace the flows of dense gas in the Galactic Centre. We find the kinematic structure of gas within the inner 500pc of the Galaxy is consistent with recent predictions for the dynamical evolution of gas flows in the centre of the Milky Way. We confirm a recent finding that the dense gas in the inner 100pc has an oscillatory kinematic structure with characteristic length scale of ~20pc, and also identify similar oscillatory kinematic structure in the gas at radii larger than 100pc. Finally, we make all of the above fits and the remaining HOPS data cubes across the 100 square degrees of the survey available to the community., Comment: 53 pages, 34 figures, 4 tables. Submitted MNRAS. Paper with full resolution images can be downloaded here: http://www.astro.ljmu.ac.uk/~snl/hops_p3.pdf

Observations of the frequencies of different rotational transitions of the methanol molecule have provided the most sensitive probe to date for changes in the proton-to-electron mass ratio, over space and time. Using methanol absorption detected in the gravitational lens system PKS B1830-211, changes in the proton-to-electron ratio over the last 7.5 billion years have been constrained to a fractional change less than 1.1e-07. Molecular absorption systems at cosmological distances present the best opportunity for constraining or measuring changes in the fundamental constants of physics over time, however, we are now at the stage where potential differences in the morphology of the absorbing systems and the background source, combined with their temporal evolution, provide the major source of uncertainty in some systems. Here we present the first milliarcsecond resolution observations of the molecular absorption system towards PKS B1830-211. We have imaged the absorption from the 12.2-GHz transition of methanol (which is redshifted to 6.45 GHz) toward the southwestern component and show that it is possibly offset from the peak of the continuum emission and partially resolved on milliarcsecond scales. Future observations of other methanol transitions with similar angular resolution offer the best prospects for reducing systematic errors in investigations of possible changes in the proton-to-electron mass ratio on cosmological scales., Comment: 8 pages, 3 figures, accepted for publication in MNRAS

We present the results of the first complete unbaised survey of the Galactic Plane for 6035-MHz excited-state hydroxyl masers undertaken as part of the Methanol Multibeam Survey. These observations cover the Galactic longitude ranges $186^{\circ}< l < 60^{\circ}$ including the Galactic Centre. We report the detection of 127 excited-state hydroxyl masers within the survey region, 47 being new sources. The positions of new detections were determined from interferometric observations with the Australia Telescope Compact Array. We discuss the association of 6035-MHz masers in our survey with the 6668-MHz masers from the MMB Survey, finding 37 likely methanol-excited-state hydroxyl masers maser pairs with physical separations of <=0.03pc and 55 pairings separated by <=0.1pc. Using these we calculate for the first time an excited-state hydroxyl maser life time of between 3.3x10^3 and 8.3x10^3 years. We also discuss the variability of the 6035-MHz masers and detection rates of counterpart 6030-MHz excited-state hydroxyl masers (28% of our sample having detection at both frequencies)., Comment: 32 pages, 11 figures, 4 tables, accepted for publication in MNRAS; Typo in figure 5 caption corrected in 2nd version; Transposition error of words 'right' and 'left' in Figure 11 caption corrected in 3rd version

This is the second paper in a series of catalogues of 22-GHz water maser observations towards the 6.7-GHz methanol masers from the Methanol Multibeam (MMB) Survey. In this paper we present our water maser observations made with the Australia Telescope Compact Array towards the masers from the MMB survey between l = 341$^{\circ}$ through the Galactic centre to l = 6$^{\circ}$. Of the 204 6.7-GHz methanol masers in this longitude range we found 101 to have associated water maser emission (~ 50 per cent). We found no difference in the 6.7-GHz methanol maser luminosities of those with and without water masers. In sources where both maser species are observed, the luminosities of the methanol and water masers are weakly correlated. Studying the mid-infrared colours from GLIMPSE we found no differences between the colours of those sources associated with both methanol and water masers and those associated with just methanol. Comparing the column density and dust mass calculated from the 870-micron thermal dust emission observed by ATLASGAL, we found no differences between those sources associated with both water and methanol masers and those with methanol only. Since water masers are collisionally pumped and often show emission further away from their accompanying YSO than the radiatively pumped 6.7-GHz methanol masers, it is likely water masers are not as tightly correlated to the evolution of the parent YSO and so do not trace such a well defined evolutionary state as 6.7-GHz methanol masers., Comment: 23 pages, 10 figures, accepted for publication in MNRAS

We present a continuing study of a sample 44 molecular outflows, observed in 13CO lines, closely associated with 6.7GHz methanol masers, hence called Methanol Maser Associated Outflows (MMAOs). We compare MMAO properties with those of outflows from other surveys in the literature. In general, MMAOs follow similar trends, but show a deficit in number at low masses and momenta, with a corresponding higher fraction at the high end of the distributions. A similar trend is seen for the dynamical timescales of MMAOs. We argue that the lack of relatively low mass and young flows in MMAOs is due to the inherent selection-bias in the sample, i.e. its direct association with 6.7GHz methanol masers. This implies that methanol masers must switch on after the onset of outflows (hence accretion), and not before a sufficient abundance of methanol is liberated from icy dust mantles. Consequently the average dynamical age of MMAOs is older than for the general population of molecular outflows. We propose an adjusted evolutionary sequence of outflow and maser occurrence in the hot core phase, where methanol masers turn on after the onset of the outflow phase., Comment: 11 pages, 10 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society

We have selected the positions of 54 6.7GHz methanol masers from the Methanol Multibeam Survey catalogue, covering a range of longitudes between $20^{\circ}$ and $34^{\circ}$ of the Galactic Plane. These positions were mapped in the J=3-2 transition of both the $\rm{^{13}CO}$ and $\rm{C^{18}O}$ lines. A total of 58 $\rm{^{13}CO}$ emission peaks are found in the vicinity of these maser positions. We search for outflows around all $\rm{^{13}CO}$ peaks, and find evidence for high-velocity gas in all cases, spatially resolving the red and blue outflow lobes in 55 cases. Of these sources, 44 have resolved kinematic distances, and are closely associated with the 6.7GHz masers, a sub-set referred to as Methanol Maser Associated Outflows (MMAOs). We calculate the masses of the clumps associated with each peak using 870 $\rm{\mu m}$ continuum emission from the ATLASGAL survey. A strong correlation is seen between the clump mass and both outflow mass and mechanical force, lending support to models in which accretion is strongly linked to outflow. We find that the scaling law between outflow activity and clump masses observed for low-mass objects, is also followed by the MMAOs in this study, indicating a commonality in the formation processes of low-mass and high-mass stars., Comment: Accepted for publication in MNRAS

The Australia Telescope Compact Array has been used to search for 22-GHz water masers towards the 119 6.7-GHz methanol masers detected in the Methanol Multi-Beam survey between Galactic longitudes 6 and 20 degrees; we find water masers associated with 55 (~46 per cent). Methanol masers with associated water masers have a higher mean integrated luminosity than those without and there is a general trend for sources with more luminous 6.7-GHz methanol masers to be associated with more luminous water maser emission. We have inspected the GLIMPSE three colour images of the regions surrounding the masers and cross-matched the maser positions with existing catalogues of Extended Green Objects and Infrared Dark Clouds. We find more Extended Green Objects at sites where both methanol and water masers are present than at sites with only methanol masers, but no significant difference in the fraction embedded within Infrared Dark Clouds. Analysis of the 1.1-mm dust emission shows dust clumps associated with masers that have greater flux densities and higher column densities than those without. Dust clumps associated with both water and 6.7-GHz methanol masers are generally the most compact clumps followed by those associated with only methanol then the clumps without associated maser emission. We conclude that protostars with both methanol and water masers are often older than those with only methanol, however, we suggest that the evolutionary phase traced by water masers is not as well defined as for 6.7-GHz methanol masers., Comment: To be published in the Monthly Notices of the Royal Astronomical Society

The Australia Telescope Compact Array (ATCA) has been used for high angular resolution imaging of 71 southern class I methanol maser sources quasi-simultaneously at 36 and 44 GHz. The data reveal a high level of morphological and kinematical complexity, and allow us to demonstrate associations, at arcsecond precision, of the class I maser emission with outflows, expanding HII regions, dark clouds, shocks traced by the 4.5-micron emission and 8.0-micron filaments. More than 700 maser component features were found at each of the two methanol transitions, but with only 23 per cent recognisable at both transitions; the morphology of class I emission is much better revealed by our survey of both transitions, compared with either one alone. We found that the number of masers falls exponentially with the projected linear distance from the associated class II 6.7-GHz methanol maser. This distribution has a scale of 263+/-15 mpc, irrespective of the transition. The class I masers associated with OH masers were found to have a tendency to be more spread out, both spatially and in the velocity domain. This is consistent with the expectation that such sources are more evolved. Apart from a small number of high-velocity components (which are largely blue-shifted and predominantly seen at 36 GHz), the velocity distribution was found to be Gaussian, peaking near the systemic velocity of the region, which had been estimated as the middle of the velocity interval of the associated class II methanol maser at 6.7 GHz. The mean indicated a small, but significant blue shift asymmetry of -0.57 km/s (uncertainties are 0.06 and 0.07 km/s for the 36- and 44-GHz masers, respectively) with respect to the 6.7-GHz masers. The standard deviation of the velocity distribution was found to be 3.65+/-0.05 and 3.32+/-0.07 km/s for the 36- and 44-GHz masers, respectively., Comment: 35 pages, 7 figures, 3 tables, full versions of figure 1 and table 3 are available online only as ancillary data, accepted for publication by MNRAS

SPLASH (the Southern Parkes Large-Area Survey in Hydroxyl) is a sensitive, unbiased and fully-sampled survey of the Southern Galactic Plane and Galactic Centre in all four ground-state transitions of the hydroxyl (OH) radical. The survey provides a deep census of 1612-, 1665-, 1667- and 1720-MHz OH absorption and emission from the Galactic ISM, and is also an unbiased search for maser sources in these transitions. We present here first results from the SPLASH pilot region, which covers Galactic longitudes 334 to 344 degrees and latitudes of -2 to +2 degrees. Diffuse OH is widely detected in all four transitions, with optical depths that are always small (averaged over the Parkes beam), and with departures from LTE common even in the 1665- and 1667-MHz main lines. To a 3$\sigma$ sensitivity of 30 mK, we find no evidence of OH envelopes extending beyond the CO-bright regions of molecular cloud complexes, and conclude that the similarity of the OH excitation temperature and the level of the continuum background is at least partly responsible for this. We detect masers and maser candidates in all four transitions, approximately 50 per cent of which are new detections. This implies that SPLASH will produce a substantial increase in the known population of ground-state OH masers in the Southern Galactic Plane., Comment: 20 pages, 9 figures, accepted for publication in MNRAS

The Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey aims to characterise the physical and chemical evolution of high-mass star-forming clumps. Exploiting the unique broad frequency range and on-the-fly mapping capabilities of the Australia Telescope National Facility Mopra 22 m single-dish telescope, MALT90 has obtained 3' x 3' maps toward ~2000 dense molecular clumps identified in the ATLASGAL 870 um Galactic plane survey. The clumps were selected to host the early stages of high-mass star formation and to span the complete range in their evolutionary states (from prestellar, to protostellar, and on to HII regions and photodissociation regions). Because MALT90 mapped 16 lines simultaneously with excellent spatial (38") and spectral (0.11 km/s) resolution, the data reveal a wealth of information about the clump's morphologies, chemistry, and kinematics. In this paper we outline the survey strategy, observing mode, data reduction procedure, and highlight some early science results. All MALT90 raw and processed data products are available to the community. With its unprecedented large sample of clumps, MALT90 is the largest survey of its type ever conducted and an excellent resource for identifying interesting candidates for high resolution studies with ALMA., Comment: Accepted to PASA, 13 pages

An Australia Telescope Compact Array search for 22 GHz water masers towards 6.7 GHz class II methanol masers detected in the Methanol Multibeam (MMB) survey has resulted in the detection of extremely high velocity emission from one of the sources. The water maser emission associated with this young stellar object covers a velocity span of nearly 300 km/s. The highest velocity water maser emission is red-shifted from the systemic velocity by 250 km/s, which is a new record for high-mass star formation regions. The maser is associated with a very young late O, or early B star, which may still be actively accreting matter (and driving the extreme outflow). If that is the case future observations of the kinematics of this water maser will provide a unique probe of accretion processes in the highest mass young stellar objects and test models of water maser formation., Comment: Accepted for publication in ApJ Letters, 6 pages, 4 figures

We report the detection of four water masers within the Small Magellanic Cloud (SMC); two discovered with the 70-m Tidbinbilla radio telescope, and two discovered with the Australia Telescope Compact Array (ATCA). Precise positions of all four masers have been derived from ATCA observations, and the characteristics of each water maser have been monitored over a period of several years. Sensitive observations towards two previously detected water masers reported in the literature failed to detect any emission. The detected water masers show evidence of higher levels of temporal variability than equivalent Galactic sources, and one of the features associated with NGC346 IR1 shows an acceleration of 9.6 km/s yr^-1 over a 31 day period. Sensitive targeted observations for methanol and OH masers failed to detect any accompanying emission - in the case of methanol perhaps highlighting an under abundance in the SMC, consistent with expectations due to lower metallicity. The water masers are both bright and compact making them excellent targets for Very Long Baseline Interferometry (VLBI) observations, which can potentially measure the proper motion of the SMC (~1 - 2 mas yr^-1) with temporal baselines of ~12 months. Such observations would utilise sources associated with only the current epoch of star formation and hence have several advantages over alternative methods.

We have used the Australia Telescope National Facility Mopra 22-m antenna to search for 37.7-GHz (7(-2) - 8(-1}E) methanol masers towards a sample of thirty six class II methanol masers. The target sources are the most luminous class II methanol masers not previously searched for this transition, with isotropic peak 12.2-GHz maser luminosity greater than 250 Jy/kpc^2 and isotropic peak 6.7-GHz maser luminosity greater than 800 Jy/kpc^2. Seven new 37.7-GHz methanol masers were detected as a result of the search. The detection rate for 37.7-GHz methanol masers towards a complete sample of all such class II methanol maser sites south of declination -20 deg is at least 30 percent. The relatively high detection rate for this rare methanol transition is in line with previous predictions that the 37.7-GHz transition is associated with a late stage of the class II methanol maser phase of high-mass star formation. We find that there is a modest correlation between the ratio of the 6.7- and 37.7-GHz maser peak intensity and the 6.7- and 12.2-GHz maser peak intensity (correlation coefficient 0.63 in a log-log plot). We detected one new 38.3-GHz (6(2) - 5(3)A-) methanol maser towards G335.789+0.174. This is only the fourth source for which maser emission has been detected in this transition and it is the only one for which emission is not also observed in the 38.5-GHz 6(2) - 5(3)A+ transition., Comment: Accepted for publication in MNRAS, 18 pages, 6 figures

We present a study of the mid-infrared environments and association with star formation tracers of 6.7 GHz methanol masers taken from the Methanol Multi-Beam (MMB) Survey. Our ultimate goal is to establish the mass of the host star and its evolutionary stage for each maser site. As a first step, the GLIMPSE survey of the Galactic Plane is utilised to investigate the environment of 776 methanol masers and we find that while the majority of the masers are associated with mid-infrared counterparts, a significant fraction (17%) are not associated with any detectable mid-infrared emission. A number of the maser counterparts are clearly extended with respect to the GLIMPSE point spread function and we implement an adaptive non-circular aperture photometry (ANCAP) technique to determine the fluxes of the maser counterparts. The ANCAP technique doubles the number of masers with flux information at all four wavelengths compared to the number of the corresponding counterparts obtained from the GLIMPSE Point Source Catalogue. The colours of the maser counterparts are found to be very similar to the smaller study carried out by Ellingsen (2006). The MMB masers are weakly associated with Extended Green Objects (EGOs) and Red MSX Survey (RMS) embedded sources (YSO and HII classifications) with 18% and 12% of masers associated with these objects respectively. The majority of MMB masers (60%) have detectable GLIMPSE infrared counterparts but have not been identified with previously recognised tracers of massive star formation; this confirms that the MMB survey has the potential to identify massive star forming regions independent of infrared selection., Comment: 14 pages, 11 figures. Some figures reduced in resolution for this version. Accepted by MNRAS. Note: Table 1 will be available in its entirety upon publication of the article in MNRAS

The details of the physical process through which high-mass stars form remains nearly as much of a mystery now as it was when the Parkes radio telescope commenced operation. The energy output from high-mass stars influence, or directly drive many important processes in the evolution of galaxies and so understanding in detail when and how they form is important for a broad range of fields of astrophysics. Interstellar masers are one of the most readily observed signposts of regions where young high-mass stars have formed. We have recently made great progress towards using the different maser species and transitions to construct a maser-based evolutionary timeline for high-mass star formation. Here we give an overview of this work, highlighting the particular contribution that past and on-going observations with the Parkes 64m radio telescope have made to this area., Comment: Published electronically in Proceedings "Science with Parkes @ 50 Years Young", 2012, Ed. Robert Braun. Conference link is, http://www.atnf.csiro.au/research/conferences/Parkes50th/ProcPapers/ellingsen.pdf

The H2O Southern Galactic Plane Survey (HOPS) has mapped a 100 degree strip of the Galactic plane (-70deg > l > 30deg, |b| < 0.5deg) using the 22-m Mopra antenna at 12-mm wavelengths. Observations were conducted in on-the-fly mode using the Mopra spectrometer (MOPS), targeting water masers, thermal molecular emission and radio-recombination lines. Foremost among the thermal lines are the 23 GHz transitions of NH3 J,K = (1,1) and (2,2), which trace the densest parts of molecular clouds (n > 10^4 cm^{-3}). In this paper we present the NH3 (1,1) and (2,2) data, which have a resolution of 2 arcmin and cover a velocity range of +/-200 km/s. The median sensitivity of the NH3 data-cubes is sigma_Tmb = 0.20 +/1 0.06 K. For the (1,1) transition this sensitivity equates to a 3.2 kpc distance limit for detecting a 20 K, 400 Msun cloud at the 5-sigma level. Similar clouds of mass 5,000 Msun would be detected as far as the Galactic centre, while 30,000 Msun clouds would be seen across the Galaxy. We have developed an automatic emission finding procedure based on the ATNF DUCHAMP software and have used it to create a new catalogue of 669 dense molecular clouds. The catalogue is 100 percent complete at the 5-sigma detection limit (Tmb = 1.0 K). A preliminary analysis of the ensemble cloud properties suggest that the near kinematic distances are favoured. The cloud positions are consistent with current models of the Galaxy containing a long bar. Combined with other Galactic plane surveys this new molecular-line dataset constitutes a key tool for examining Galactic structure and evolution. Data-cubes, spectra and catalogues are available to the community via the HOPS website., Comment: 22 pages, 19 figures. Accepted for publication in MNRAS (25-July-2012)

We review properties of all known collisionally pumped (class I) methanol maser series based on observations with the Australia Telescope Compact Array (ATCA) and the Mopra radio telescope. Masers at 36, 84, 44 and 95 GHz are most widespread, while 9.9, 25, 23.4 and 104 GHz masers are much rarer, tracing the most energetic shocks. A survey of many southern masers at 36 and 44 GHz suggests that these two transitions are highly complementary. The 23.4 GHz maser is a new type of rare class I methanol maser, detected only in two high-mass star-forming regions, G357.97-0.16 and G343.12-0.06, and showing a behaviour similar to 9.9, 25 and 104 GHz masers. Interferometric positions suggest that shocks responsible for class I masers could arise from a range of phenomena, not merely an outflow scenario. For example, some masers might be caused by interaction of an expanding HII region with its surrounding molecular cloud. This has implications for evolutionary sequences incorporating class I methanol masers if they appear more than once during the evolution of the star-forming region. We also make predictions for candidate maser transitions at the ALMA frequency range., Comment: 8 pages, 2 figures, to appear in proceedings for IAUS 287: Cosmic Masers - from OH to H0

We have used the Australia Telescope Compact Array to measure the absorption from the 2(0) - 3(-1}E 12.2 GHz transition of methanol towards the z=0.89 lensing galaxy in the PKS B 1830-211 gravitational lens system. Comparison of the velocity of the main absorption feature with the published absorption spectrum from the 1(0) - 2(-1)E transition of methanol shows that they differ by -0.6 +/- 1.6 km/s . We can use these observations to constrain the changes in the proton-to-electron mass ratio from z=0.89 to the present to 0.8 +/- 2.1 x 10^-7. This result is consistent, and of similar precision to recent observations at z = 0.68 achieved through comparison of a variety of rotational and inversion transitions, and approximately a factor of 2 better than previous constraints obtained in this source. Future more sensitive observations which incorporate additional rotational methanol transitions offer the prospect of improving current results by a factor of 5-10., Comment: 8 pages, 1 figure, accepted for publication in ApJ Letters

We present the fourth portion of a Galactic Plane survey of methanol masers at 6668 MHz, spanning the longitude range 186 degrees to 330 degrees. We report 207 maser detections, 89 new to the survey. This completes the southern sky part of the Methanol Multibeam survey and includes a large proportion of new sources, 43%. We also include results from blind observations of the Orion-Monoceros star forming region, formally outside the latitude range of the Methanol Multibeam survey; only the four previously known methanol emitting sites were detected, of which we present new positions and spectra for masers at Orion-A (south) and Orion-B, obtained with the MERLIN array., Comment: 39 Pages, 8 Figures, accepted for publication in MNRAS

We report the results of a search for class II methanol masers at 37.7, 38.3 and 38.5 GHz towards a sample of 70 high-mass star formation regions. We primarily searched towards regions known to show emission either from the 107 GHz class II methanol maser transition, or from the 6.035 GHz excited OH transition. We detected maser emission from 13 sources in the 37.7 GHz transition, eight of these being new detections. We detected maser emission from three sources in the 38 GHz transitions, one of which is a new detection. We find that 37.7 GHz methanol masers are only associated with the most luminous 6.7 and 12.2 GHz methanol maser sources, which in turn are hypothesised to be the oldest class II methanol sources. We suggest that the 37.7 GHz methanol masers are associated with a brief evolutionary phase (of 1000-4000 years) prior to the cessation of class II methanol maser activity in the associated high-mass star formation region., Comment: 14 pages, 4 figures, accepted for publication in ApJ

We present first results of the H_2O Southern Galactic Plane Survey (HOPS), using the Mopra radiotelescope with a broad band backend and a beam size of about 2'. We have observed 100 square degrees of the southern Galactic plane at 12mm (19.5 to 27.5GHz), including spectral line emission from water masers, multiple metastable transitions of ammonia, cyanoacetylene, methanol and radio recombination lines. In this paper, we report on the characteristics of the survey and water maser emission. We find 540 water masers, of which 334 are new detections. The strongest maser is 3933Jy and the weakest is 0.7Jy, with 62 masers over 100Jy. In 14 maser sites, the spread in velocity of the water maser emission exceeds 100km/s. In one region, the water maser velocities are separated by 351.3km/s. The rms noise levels are typically between 1-2Jy, with 95% of the survey under 2Jy. We estimate completeness limits of 98% at around 8.4Jy and 50% at around 5.5Jy. We estimate that there are between 800 and 1500 water masers in the Galaxy that are detectable in a survey with similar completeness limits to HOPS. We report possible masers in NH_3 (11,9) and (8,6) emission towards G19.61-0.23 and in the NH_3 (3,3) line towards G23.33-0.30., Comment: accepted for publication in MNRAS

We explore the longitude-velocity distribution of 6.7-GHz methanol masers in the context of the inner structure of our Galaxy. We analyse the correlation in velocities within this distribution and identify density enhancements indicating large-scale regions of enhanced star formation. These are interpreted as the starting points of the spiral arms and the interaction of the Galactic bar with the 3-kpc arms. The methanol masers support the presence of a long thin bar with a 45 degree orientation. Signatures of the full 3-kpc arm structure are seen, including a prominent tangent at approximately -22 degrees Galactic longitude. We compare this distribution with existing models of the gas dynamics of our Galaxy. The 3-kpc arm structure appears likely to correspond to the radius of corotation resonance of the bar, with the bar on its inner surface and the starting points of the spiral arms on its outer surface., Comment: 35 pages, 11 figures. Accepted for publication in ApJ

We report the first detection of a methanol maser in the 10(1)-9(2)A- transition at 23.4 GHz, discovered during the H2O southern Galactic Plane Survey (HOPS) with the 22-m Mopra radio telescope. In the region covered by HOPS, the 23.4 GHz maser was found at only one location, G357.97-0.16, which was also a prominent source of maser emission in the J(2)-J(1)E series near 25 GHz. The Australia Telescope Compact Array (ATCA) was used to follow up these detections at high angular resolution and prove the maser nature of the observed emission. The analysis shows that the new methanol maser at 23.4 GHz is a class I maser, which has properties similar to the 9.9 and 25 GHz masers (i.e. traces strong shocks with higher than average temperature and density). All class I masers were found to originate at the same spatial location (within the measurement uncertainty of 0.5 arcseconds) in the vicinity of the dominant infrared source, but at a clearly distinct position from nearby OH, H2O and class II methanol masers at 6.7 GHz. All maser species are distributed approximately on a line, but it is not clear at present whether this has any physical significance. We also detected a weak (1.3 mJy) continuum source at 25 GHz near the OH maser (at the most northern site, associated with a class II methanol maser and an H2O maser renowned for its extremely wide spread of velocity components). The continuum source has not been reported at lower frequencies and is therefore a candidate hypercompact HII region. We also used the ATCA to find the strongest and only fifth known 9.9 GHz maser towards G357.97-0.16 and another 23.4 GHz maser towards G343.12-0.06 not seen in HOPS., Comment: 7 pages, 2 figures, 2 tables, accepted by MNRAS

We present the second portion of an unbiased survey of the Galactic plane for 6668-MHz methanol masers. This section of the survey spans the longitude range 6 degrees to 20 degrees. We report the detection of 119 maser sources, of which 42 are new discoveries. The masers are tightly constrained to the Galactic plane, with only four outside a latitude range of +/- 1 degree. This longitude region includes the brightest known 6668-MHz methanol maser, 9.621+0.196, as well as the two brightest newly discovered sources in the southern survey as a whole. We list all the sources associated with the 3-kpc arms within +/- 15 degrees longitude and consider further candidates beyond 15 degrees longitude. We identify three new sources associated with the Galactic bar and comment on the density of masers in relation to the bar orientation., Comment: 25 pages, 4 figures, accepted for publication in MNRAS

We have conducted a Galactic plane survey of methanol masers at 6668 MHz using a 7-beam receiver on the Parkes telescope. Here we present results from the first part, which provides sensitive unbiased coverage of a large region around the Galactic Centre. Details are given for 183 methanol maser sites in the longitude range 345$^{\circ}$ through the Galactic Centre to 6$^{\circ}$. Within 6$^{\circ}$ of the Centre, we found 88 maser sites, of which more than half (48) are new discoveries. The masers are confined to a narrow Galactic latitude range, indicative of many sources at the Galactic Centre distance and beyond, and confined to a thin disk population; there is no high latitude population that might be ascribed to the Galactic Bulge. Within 2$^{\circ}$ of the Galactic Centre the maser velocities all lie between -60 and +77 \kms, a range much smaller than the 540 \kms range observed in CO. Elsewhere, the maser with highest positive velocity (+107 \kms) occurs, surprisingly, near longitude 355$^{\circ}$ and is probably attributable to the Galactic bar. The maser with the most negative velocity (-127 \kms) is near longitude 346$^{\circ}$, within the longitude-velocity locus of the near side of the `3-kpc arm'. It has the most extreme velocity of a clear population of masers associated with the near and far sides of the 3-kpc arm. Closer to the Galactic Centre the maser space density is generally low, except within 0.25 kpc of the Centre itself, the `Galactic Centre Zone', where it is 50 times higher, which is hinted at by the longitude distribution, and confirmed by the unusual velocities., Comment: 35 pages, 5 figures

We report the results of a sensitive search for 12.2 GHz methanol maser emission towards a sample of eight high-mass star formation regions in the Large Magellanic Clouds which have been detected in other maser transitions. We detected one source towards the star formation region N105a. This is the first detection of a 12.2 GHz methanol maser outside our Galaxy. We also made near-contemporaneous observations of the 6.7 GHz methanol and 22 GHz water masers towards these sources, resulting in the detection of water maser emission in six new sources, including one associated with the strongest 6.7 GHz maser in the Magellanic Clouds IRAS 05011-6815. The majority of the maser sources are closely associated with objects identified as likely Young Stellar Objects (YSO) on the basis of Spitzer Space Telescope observations. We find that the YSOs associated with masers tend to be more luminous and have redder infrared colours than the sample as a whole. SED modeling of the YSOs shows that the masers are associated with sources of higher central mass, total luminosity and ambient density than the majority of YSOs in the LMC. This is consistent with the well-established relationship between luminous methanol and water masers and young, high-mass objects observed in the Galaxy., Comment: 15 pages, 10 figures, accepted for publication in MNRAS

We report the results of a search for 12.2-GHz methanol maser emission, targeted towards 113 known 6.7-GHz methanol masers associated with 1.2-mm dust continuum emission. Observations were carried out with the Australia Telescope National Facility (ATNF) Parkes 64-m radio telescope in the period 2008 June 20 - 25. We detect 68 12.2-GHz methanol masers with flux densities in excess of our 5-sigma detection limit of 0.55 Jy, 30 of which are new discoveries. This equates to a detection rate of 60 per cent, similar to previous searches of comparable sensitivity. We have made a statistical investigation of the properties of the 1.2-mm dust clumps with and without associated 6.7-GHz methanol maser and find that 6.7-GHz methanol masers are associated with 1.2-mm dust clumps with high flux densities, masses and radii. We additionally find that 6.7-GHz methanol masers with higher peak luminosities are associated with less dense 1.2-mm dust clumps than those 6.7-GHz methanol masers with lower luminosities. We suggest that this indicates that more luminous 6.7-GHz methanol masers are generally associated with a later evolutionary phase of massive star formation than less luminous 6.7-GHz methanol maser sources. Analysis of the 6.7-GHz associated 1.2-mm dust clumps with and without associated 12.2-GHz methanol maser emission shows that clumps associated with both class II methanol maser transitions are less dense than those with no associated 12.2-GHz methanol maser emission; suggesting that 12.2-GHz methanol masers are associated with a later evolutionary phase of massive star formation. We present an evolutionary sequence for masers in high-mass star formation regions, placing quantitative estimates on the relative lifetimes for the first time., Comment: Accepted to MNRAS 2009 October 4

Observations of H$_2$O masers towards the post-AGB star and water fountain source OH 009.1--0.4 were made as part of HOPS (The H$_2$O southern galactic Plane Survey), with the Mopra radiotelescope. Together with followup observations using the Australia Telescope Compact Array (ATCA), we have identified H$_2$O maser emission over a velocity spread of nearly 400km/s (--109 to +289km/s). This velocity spread appears to be the largest of any known maser source in our Galaxy. High resolution observations with the ATCA indicate the maser emission is confined to a region $0\farcs3 \times 0\farcs3$ and shows weak evidence for a separation of the red- and blueshifted maser spots. We are unable to determine if the water fountain is projected along the line of sight, or is inclined, but either way OH 009.1--0.4 is an interesting source, worthy of followup observations., Comment: Accepted by MNRAS Lett

A new 7-beam 6-7 GHz receiver has been built to survey the Galaxy and the Magellanic Clouds for newly forming high-mass stars that are pinpointed by strong methanol maser emission at 6668 MHz. The receiver was jointly constructed by Jodrell Bank Observatory (JBO) and the Australia Telescope National Facility (ATNF) and allows simultaneous coverage at 6668 and 6035 MHz. It was successfully commissioned at Parkes in January 2006 and is now being used to conduct the Parkes-Jodrell multibeam maser survey of the Milky Way. This will be the first systematic survey of the entire Galactic plane for masers of not only 6668-MHz methanol, but also 6035-MHz excited-state hydroxyl. The survey is two orders of magnitude faster than most previous systematic surveys and has an rms noise level of ~0.17 Jy.This paper describes the observational strategy, techniques and reduction procedures of the Galactic and Magellanic Cloud surveys, together with deeper, pointed, follow-up observations and complementary observations with other instruments. It also includes an estimate of the survey detection efficiency. The 111 days of observations with the Parkes telescope have so far yielded >800 methanol sources, of which ~350 are new discoveries. The whole project will provide the first comprehensive Galaxy-wide catalogue of 6668-MHz and 6035-MHz masers., Comment: 13 pages, 13 figures, accepted for publication by MNRAS

We present the results of the first complete survey of the Large and Small Magellanic Clouds for 6668-MHz methanol and 6035-MHz excited-state hydroxyl masers. In addition to the survey, higher-sensitivity targeted searches towards known star-formation regions were conducted. The observations yielded the discovery of a fourth 6668-MHz methanol maser in the Large Magellanic Cloud (LMC), found towards the star-forming region N160a, and a second 6035-MHz excited-state hydroxyl maser, found towards N157a. We have also re-observed the three previously known 6668-MHz methanol masers and the single 6035-MHz hydroxyl maser. We failed to detect emission from either transition in the Small Magellanic Cloud. All observations were initially made using the Methanol Multibeam (MMB) survey receiver on the 64-m Parkes telescope as part of the MMB project and accurate positions have been measured with the Australia Telescope Compact Array (ATCA). We compare the maser populations in the Magellanic Clouds with those of our Galaxy and discuss their implications for the relative rates of massive star-formation, heavy metal abundance, and the abundance of complex molecules. The LMC maser populations are demonstrated to be smaller than their Milky Way counterparts. Methanol masers are under-abundant by a factor of ~45, whilst hydroxyl and water masers are a factor of ~10 less abundant than our Galaxy., Comment: 10 pages, 5 figures, accepted for publication by MNRAS

Interstellar masers are unique probes of the environments in which they arise. In studies of high-mass star formation their primary function has been as signposts of these regions and they have been used as probes of the kinematics and physical conditions in only a few sources. With a few notable exceptions, we know relatively little about the evolutionary phase the different maser species trace, nor their location with respect to other star formation tracers. While detailed studies of a small number of maser regions can reveal much about them, other information can only be obtained through large, systematic searches. In particular, such surveys are vital in efforts to determine an evolutionary sequence for the common maser species, and there is growing evidence that methanol masers may trace an earlier phase than the other common maser species of OH and water., Comment: 5 pages, invited presentation at IAU242 "Astrophysical Masers and their environments"

We report the results of a blind search for 22-GHz water masers in two regions, covering approximately half a square degree, within the giant molecular cloud associated with RCW 106. The complete search of the two regions was carried out with the 26-m Mount Pleasant radio telescope and resulted in the detection of nine water masers, five of which are new detections. Australia Telescope Compact Array (ATCA) observations of these detections have allowed us to obtain positions with arcsecond accuracy, allowing meaningful comparison with infrared and molecular data for the region. We find that for the regions surveyed there are more water masers than either 6.7-GHz methanol, or main-line OH masers. The water masers are concentrated towards the central axis of the star formation region, in contrast to the 6.7-GHz methanol masers which tend to be located near the periphery. The colours of the GLIMPSE point sources associated with the water masers are similar to those of 6.7-GHz methanol masers, but slightly less red. We have made a statistical investigation of the properties of the 13CO and 1.2-mm dust clumps with and without associated water masers. We find that the water masers are associated with the more massive, denser and brighter 13CO and 1.2-mm dust clumps. We present statistical models that are able to predict those 13CO and 1.2-mm dust clumps that are likely to have associated water masers, with a low misclassification rate., Comment: 18 pages, 8 figures