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Intended and unintended radio emissions from satellites can interfere with sensitive radio telescopes in the frequency ranges of key experiments in astrophysics and cosmology. We detect strong intended and unintended electromagnetic radiation from Starlink satellites at the site of the future SKA-Low facility in Western Australia, using an SKA-low prototype station known as the Engineering Development Array version 2 (EDA2). We aim to show that Starlink satellites are easily detectable utilising a configuration of low frequency radio antennas representative of an SKA-Low 'station' and that our results complement similar findings with the LOFAR telescope. Utilising the EDA2 at frequencies of 137.5 MHz and 159.4 MHz, we detect trains of Starlink satellites on 2023-03-17/18 and 2021-11-16/17, respectively, via the formation of all-sky images with a frequency resolution of 0.926 MHz and a time resolution of 2 s. Time differencing techniques are utilised to isolate and characterise the transmissions from Starlink and other satellites. We observe Starlink satellites reaching intensities of $10^6$ Jy/beam, with the detected transmissions exhibiting a range of behaviours, from periodic bursts to steady transmission. The results are notable because they demonstrate that Starlink satellites are detected in the SKA-Low frequency range, transmitting both intentionally and unintentionally. Follow-up work and discussion are needed to identify the cause of this unintentional radiation as it has the potential to interfere with SKA-Low science. Our results indicate that both intended and unintended radiation from Starlink satellites will be detrimental to key SKA science goals without mitigation. Continued conversation with SpaceX could potentially result in future mitigations which the EDA2 instrument could efficiently monitor and characterise at the SKA-Low site.

Cm-wavelength radio continuum emission in excess of free-free, synchrotron and Rayleigh-Jeans dust emission (excess microwave emission, EME), and often called `anomalous microwave emission', is bright in molecular cloud regions exposed to UV radiation, i.e. in photo-dissociation regions (PDRs). The EME correlates with IR dust emission on degree angular scales. Resolved observations of well-studied PDRs are needed to compare the spectral variations of the cm-continuum with tracers of physical conditions and of the dust grain population. The EME is particularly bright in the regions of the rho Ophiuchi molecular cloud (rho Oph) that surround the earliest type star in the complex, HD 147889, where the peak signal stems from the filament known as the rho Oph-W PDR. Here we report on ATCA observations of rho Oph-W that resolve the width of the filament. We recover extended emission using a variant of non-parametric image synthesis performed in the sky plane. The multi-frequency 17 GHz to 39 GHz mosaics reveal spectral variations in the cm-wavelength continuum. At ~30 arcsec resolutions, the 17-20 GHz intensities follow tightly the mid-IR, Icm propto I(8 um), despite the breakdown of this correlation on larger scales. However, while the 33-39 GHz filament is parallel to IRAC 8 mum, it is offset by 15-20 arcsec towards the UV source. Such morphological differences in frequency reflect spectral variations, which we quantify spectroscopically as a sharp and steepening high-frequency cutoff, interpreted in terms of the spinning dust emission mechanism as a minimum grain size a_cutoff ~ 6 +- 1A that increases deeper into the PDR., Comment: accepted for publication in MNRAS

We describe a new mm-wave molecular-line mapping survey of the southern Galactic Plane and its first data releases. The Three-mm Ultimate Mopra Milky Way Survey (ThrUMMS) maps a 60{\deg}x2{\deg} sector of our Galaxy's fourth quadrant, using a combination of fast mapping techniques with the Mopra radio telescope, simultaneously in the J=1-0 lines of $^{12}$CO, $^{13}$CO, C$^{18}$O, and CN near 112 GHz at ~arcminute and ~0.3 km s$^{-1}$ resolution, with ~2 K channel$^{-1}$ sensitivity for $^{12}$CO and ~1 K channel$^{-1}$ for the other transitions. The calibrated data cubes from these observations are made available to the community after processing through our pipeline. Here, we describe the motivation for ThrUMMS, the development of new observing techniques for Mopra, and how these techniques were optimised to the objectives of the survey. We showcase some sample data products and describe the first science results on CO-isotopologue line ratios. These vary dramatically across the Galactic Plane, indicating a very wide range of optical depth and excitation conditions, from warm and translucent to cold and opaque. The population of cold clouds in particular have optical depths for $^{12}$CO easily exceeding 100. We derive a new, nonlinear conversion law from $^{12}$CO integrated intensity to column density, which suggests that the molecular mass traced by CO in the Galactic disk may have been substantially underestimated. This further suggests that some global relationships in disk galaxies, such as star formation laws, may need to be recalibrated. The large ThrUMMS team is proceeding with several other science investigations., Comment: 24 pages, 21 figures. Accepted by ApJ. Higher resolution version (17 Mb) available at http://www.astro.ufl.edu/thrumms

We present a millimetre-wave site characterisation for the Australia Telescope Compact Array (ATCA) based on nearly 9 years of data from a seeing monitor operating at this facility. The seeing monitor, which measures the phase fluctuations in the signal from a geosynchronous satellite over a 230\,m baseline caused by water vapour fluctuations along their sight lines, provides an almost gapless record since 2005, with high time resolution. We determine the root mean square (rms) of the path length variations as a function of time of day and season. Under the assumption of the "frozen screen" hypothesis, we also determine the Kolomogorov exponent, $\alpha$, for the turbulence and the phase screen speed. From these, we determine the millimetre-wave seeing at $\lambda = 3.3$\,mm. Based on the magnitude of the rms path length variations, we estimate the expected fraction of the available observing time when interferometry could be successfully conducted using the ATCA, as a function of observing frequency and antenna baseline, for the time of day and the season. We also estimate the corresponding observing time fractions when using the water vapour radiometers (WVRs) installed on the ATCA in order to correct for the phase fluctuations occurring during the measurement of an astronomical source.

We have examined the relationship between the velocity parameters of SiO masers and the phase of the long period variable stars (LPVs) from which the masers originate. The SiO spectra from the v=1, J=1-0 (43.122 GHz; hereafter $J_{1\rightarrow0}$) and the v=1, J=2-1 (86.2434 GHz; hereafter $J_{2\rightarrow1}$) transitions have been measured using the Mopra Telescope of the Australia Telescope National Facility. One hundred twenty one sources have been observed including 47 LPVs contained in the American Association of Variable Star Observer Bulletin (2011). The epoch of maxima and the periods of the LPVs are well studied. This database of spectra allows for phase dependent comparisons and analysis not previously possible with such a large number of sources observed almost simultaneously in the two transitions over a time span of several years. The velocity centroids ($VCs$) and velocity ranges of emission ($VRs$) have been determined and compared for the two transitions as a function of phase. No obvious phase dependence has been determined for the $VC$ or $VR$. The results of this analysis are compared with past observations and existing SiO maser theory.

We present an analysis of velocity parameters derived from multi-epoch observations of the SiO maser spectra of 47 long period variables (LPVs). The velocity parameters are important to inform and constrain theoretical models of SiO maser emission and to extract information on binary orbits. Mira and R Aquarii (R Aqr) are two known binaries included in the program. The 47 LPVs are among 121 sources of the Australia Telescope National Facility (ATNF) Mopra telescope's monitoring program. Observations were carried out several times a year between 2008 and 2012 and are continuing. The SiO spectra are from the v=1, J=1-0 (43.122 GHz; hereafter J10) and the v=1, J=2-1 (86.2434 GHz; hereafter J21) transitions. For 41 of the 47 LPVs we observed both transitions nearly simultaneously in 457 observations. We have determined and compared the velocity centroids (VCs) and velocity ranges of emission (VRs) suffixed as above (10 and 21) for the two transitions - VC10, VC21, VR10, and VR21. The VCs of the two transitions are, on average, within 0.13 km s-1 of each other but are sometimes separated by a few km s-1. The VC10s are, on average, slightly more positive than the VC21s. The values of the VCs in the two transitions have been compared to justify using both of these transitions to extract binary star orbital parameters. The arithmetic mean VR10 derived from 635 observations of 47 sources is 6.4 km s-1 with a standard deviation of 3.4 km s-1 while the mean VR21 derived from 485 observations of 41 sources is 4.2 km s-1 with a standard deviation of 2.8 km s-1. The number of occurrences of VR10 and VR21versus velocity range have different distributions. The differences in the VRs indicate that the J21 and J10 emissions arise from dynamically different regions of the circumstellar environment., Comment: 4 figures 2 tables. This is an author-created, un-copyedited version of an article accepted for publication in the Astronomical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it

We have developed Water Vapour Radiometers (WVRs) for the Australia Telescope Compact Array (ATCA) that are capable of determining signal path length fluctuations by virtue of measuring small temperature fluctuations in the atmosphere using the 22.2 GHz water vapour line for each of the six antennae. By measuring the line of sight variations of the water vapour, the induced path excess and thus the phase delay can be estimated and corrections can then be applied during data reduction. This reduces decorrelation of the source signal. We demonstrate how this recovers the telescope's efficiency as well as how this improves the telescope's ability to use longer baselines at higher frequencies, thereby resulting in higher spatial resolution. A description of the WVR hardware design, their calibration and water vapour retrieval mechanism is given., Comment: 17 pages, 20 figures

We examine the historical development of astrophysical science in Antarctica from the early 20th century until today. We find three temporally overlapping eras, each having a rather distinct beginning. These are the astrogeological era of meteorite discovery, the high energy era of particle detectors, and the photon astronomy era of microwave, sub--mm and infrared telescopes, sidelined by a few niche experiments at optical wavelengths. The favourable atmospheric and geophysical conditions are briefly examined, followed by an account of the major experiments and a summary of their results., Comment: 29 pages, 10 figures, 1 table Submitted to PASA in April 2004

On examining the historical development of astrophysical science at the bottom of the world from the early 20th century until today we find three temporally overlapping eras of which each has a rather distinct beginning. These are the eras of Astrogeology, High Energy Astrophysics and Photon Astronomy. A full version of this paper will be submitted to PASA., Comment: To appear in the IAU Highlights of Astronomy, Volume 13, Edited by O. Engvold & M. Burton, Published by the Astronomical Society of the Pacific