Remotely operated astronomical radio telescope facilities that are spread over a large geographical area demand a new kind of protection from severe weather phenomena such as wind gusts and lightning. Both of these factors pose a unique danger to dish shaped antennas which many radio telescopes are based on. Structural damage can be incurred by severe wind gusts if a dish antenna is not stowed into its minimum wind profile position, and lightning protection might not be at its optimal configuration if the dish is not stowed. Traditionally, anemometers have provided wind information to base stow decisions on. In the case of thunderstorms capable of triggering microburst events however, anemometers do not provide timely enough warning, and their spot measurements are too localised to provide safety for distributed antenna networks. <p> </p>We discuss our implementation of a near real-time satellite data based severe storm warning system built for the Australian Square Kilometre Array Pathfinder (ASKAP), the methods used to diagnose convective developments, and we will show on a number of examples how well such a satellite based system can work, despite the system inherent time lag. We conclude by discussing future developments and improvements that can be made to the system for deployment with extremely large projects such as the Square Kilometre Array (SKA) currently being planned and built in South Africa and Australia that will require monitoring of an area orders of magnitude larger even than we are monitoring today. <p> </p>Using data products derived from the Advanced Himawari Imager (AHI) deployed on the Japanese Meteorological Agency’s (JMA) Himawari 8 satellite, we can obtain information on convective developments in the troposphere that are likely to result in dangerous wind gusts. This data is taken in 10 minute intervals and generally available no later than 8 minutes after the observation time, thus providing near real-time information on the weather situation. One additional challenge is the large area covered by the radio interferometers we are operating. In the case of the Australian Square Kilometre Pathfinder (ASKAP) telescope in remote West Australia’s Murchison Radio Observatory (MRO), the landmass covers dozens of square kilometers featuring 36 dish antennas of 12m diameter each.
Low frequency radio sites are susceptible to radio frequency interference (RFI) from a vast array of man-made interferers. For that reason, astronomers attempt to find sites far away from populated areas. Despite this, anomalous propagation on occasion leads to signals from far away population centres impinging on these otherwise radio quiet sites. Using an array of bespoke software and receivers, we are characterising the site of the Murchison Radio Observatory (MRO) in remote Western Australia (WA). This is the same site where the Australian Square Kilometre Pathfinder (ASKAP) is now in early science operations and also is the future site of the Australian contribution to the Square Kilometre Array (SKA) telescope, SKA low. We describe the setup of the RFI detection system used to track all known emitters providing location information, including terrestrial mobile communications, aviation, marine, and space based transmitters, most of which are used to detect and analyse anomalous propagation events and cross correlate the data with meteorological model and observational data to validate a ducting prediction model.
The Australia Telescope National Facility operates three radio telescopes: the Parkes 64m Telescope, the Australia Telescope Compact Array (ATCA), and the Mopra 22m Telescope. Scientific operation of all these is conducted by members of the investigating teams rather than by professional operators. All three can now be accessed and controlled from any location served by the internet, the telescopes themselves being unattended for part or all of the time. Here we describe the rationale, advantages, and means of implementing this operational model.
We have developed Water Vapour Radiometers (WVRs) for the Australia Telescope Compact Array that are capable of determining excess path fluctuations by virtue of measuring small temperature fluctuations in the atmosphere using the 22.3 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. In this presentation, we discuss the design of the WVRs, an uncooled quadruple filter radiometer capable of detecting water line temperature fluctuations to a sensitivity of 12 mK. The design process of the WVRs is discussed with an emphasis on the modelled sensitivity requirements, filter placement, radio frequency interference mitigation and we conclude by demonstrating how this water vapour radiometry system recovers the telescope's efficiency and image quality as well as how this improves the telescope's ability to use longer baselines at higher frequencies, thereby resulting in higher spatial resolution. We discuss a quadruple filter, uncooled 22.2 GHz Water Vapour Radiometer (WVR) system developed for the six antennae of the Australia Telescope Compact Array. The design process of the WVRs is discussed with an emphasis on the modelled sensitivity requirements, filter placement, radio frequency interference mitigation and we conclude by demonstrating how this system recovers the telescope's efficiency and image quality as well as how this improves the telescope's ability to use longer baselines at higher frequencies, thereby resulting in higher spatial resolution.
The Mopra Radio Telescope is a 22m single-dish radio telescope located near Siding Spring Observatory in New South
Wales, Australia. Its receiver systems cover the 3mm, 7mm and 12mm bands for single-dish observing, as well as the
6/3cm and 20/13cm bands used for Very Long Baseline Interferometry (VLBI). The remote location of the telescope, a
good day's drive from Sydney, made it a good candidate to implement remote observing capabilities which would no
longer require observers to travel to the telescope, but bring the telescope to them. In a first step this was implemented in
a controlled environment three years ago. It enabled remote observing from a dedicated workstation at the Australia
Telescope Compact Array (ATCA) control building some 160km away from the observatory. In a second step two years
ago, remote observing was extended to allow observing from any location in the world for qualifying observers. There
were a number of challenges that needed to be addressed, from telescope safety to internet and data link reliability,
computer security, and providing the observers with adequate situation awareness tools. The uptake by observers has
been very good with over 40% of the observing in 2009 having been executed remotely. Further, many small and
unallocated time slices were able to be productively used as they would not have warranted a trip to the observatory in
their own merit but were usable thanks to remote observing. This helped push the productivity of the Mopra telescope in
2009 to the highest figure in its 17 year history.
Recent data have shown that Dome C, on the Antarctic plateau, is an exceptional site for astronomy, with atmospheric
conditions superior to those at any existing mid-latitude site. Dome C, however, may not be the best site on the
Antarctic plateau for every kind of astronomy. The highest point of the plateau is Dome A, some 800 m higher than
Dome C. It should experience colder atmospheric temperatures, lower wind speeds, and a turbulent boundary layer that
is confined closer to the ground. The Dome A site was first visited in January 2005 via an overland traverse, conducted
by the Polar Research Institute of China. The PRIC plans to return to the site to establish a permanently manned station
within the next decade. The University of New South Wales, in collaboration with a number of international institutions,
is currently developing a remote automated site testing observatory for deployment to Dome A in the 2007/8 austral
summer as part of the International Polar Year. This self-powered observatory will be equipped with a suite of site
testing instruments measuring turbulence, optical and infrared sky background, and sub-millimetre transparency. We
present here a discussion of the objectives of the site testing campaign and the planned configuration of the observatory.