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We describe an ultra-wide-bandwidth, low-frequency receiver recently installed on the Parkes radio telescope. The receiver system provides continuous frequency coverage from 704 to 4032 MHz. For much of the band (
), the system temperature is approximately 22 K and the receiver system remains in a linear regime even in the presence of strong mobile phone transmissions. We discuss the scientific and technical aspects of the new receiver, including its astronomical objectives, as well as the feed, receiver, digitiser, and signal processor design. We describe the pipeline routines that form the archive-ready data products and how those data files can be accessed from the archives. The system performance is quantified, including the system noise and linearity, beam shape, antenna efficiency, polarisation calibration, and timing stability.
We present a millimetre-wave site characterisation for the Australia Telescope Compact Array (ATCA) based on nearly 9 yr 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 Kolmogorov exponent, α, for the turbulence and the phase screen speed. From these, we determine the millimetre-wave seeing at λ = 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 installed on the ATCA in order to correct for the phase fluctuations occurring during the measurement of an astronomical source.
We have developed water vapour radiometers (WVRs) for the Australia Telescope Compact Array 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.
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, submillimetre, 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.
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.
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