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Breakthrough Listen is a 10-yr initiative to search for signatures of technologies created by extraterrestrial civilisations at radio and optical wavelengths. Here, we detail the digital data recording system deployed for Breakthrough Listen observations at the 64-m aperture CSIRO Parkes Telescope in New South Wales, Australia. The recording system currently implements two modes: a dual-polarisation, 1.125-GHz bandwidth mode for single-beam observations, and a 26-input, 308-MHz bandwidth mode for the 21-cm multibeam receiver. The system is also designed to support a 3-GHz single-beam mode for the forthcoming Parkes ultra-wideband feed. In this paper, we present details of the system architecture, provide an overview of hardware and software, and present initial performance results.
We have observed the Vela pulsar for 1 year using a Phased Array Feed (PAF) receiver on the 12-m antenna of the Parkes Test-Bed Facility (PTF). These observations have allowed us to investigate the stability of the PAF beam weights over time, to demonstrate that pulsars can be timed over long periods using PAF technology and to detect and study the most recent glitch event that occurred on 12 December 2016. The beam weights are shown to be stable to 1% on time scales on the order of three weeks.
We have observed the Vela pulsar for 1 year using a phased array feed receiver on the 12-m antenna of the Parkes Test-Bed Facility. These observations have allowed us to investigate the stability of the phased array feed beam weights over time, to demonstrate that pulsars can be timed over long periods using phased array feed technology and to detect and study the most recent glitch event that occurred on 2016 December 12. The beam weights are shown to be stable to 1% on time scales on the order of three weeks. We discuss the implications of this for monitoring pulsars using phased array feeds on single dish telescopes.
The Southern Hemisphere VLBI Experiment (SHEVE) program is aimed at producing high-resolution images of southern radio sources. The radio telescopes of the present SHEVE array are described below and some recent results presented.
The accumulation of evidence now strongly favours interstellar scintillation (ISS) as the principal mechanism causing intra-day variability (IDV) at cm wavelengths. While ISS reduces the implied brightness temperatures, they remain uncomfortably high. The distance to the scattering screen is an important parameter in determining the actual brightness temperature encountered. The high brightness temperatures, the presence of strong and variable circular polarization and the observed lifetimes of a decade or more for several IDV sources, pose significant problems for synchrotron theory.
“The fault, dear Brutus, is not in our stars, but in ourselves, that we are underlings.” William Shakespeare, Julius Caesar
Following the ‘prompt’ radio outburst seen soon after the neutrino emission in SN 1987A (Turtle et al. 1987), we initiated a program to monitor the supernova at the Tidbinbilla Deep Space Communications Complex at 8.4 GHz in a search for radio emission from the expanding remnant. No radio emission has been detected to date (DOY 151, May 30 1988).
We present a list of bright (< 17 mag) southern QSOs and bright (< 11 mag) stars that may be suitable for the Hubble Space Telescope link between the Hipparcos astrometric reference frame and the VLBI extragalactic frame. The QSOs have been selected from various lists of radio objects and identifications. The stars have been selected from the Strasbourg (CDS) data base and from the Preliminary Second Cape Photographic Catalogue, and supplemented with stars measured from the SERC IIIa-J Schmidt survey. The list of QSOs and stars have been included in the Hipparcos and HST schedule of observations.
Intra-day variability (IDV) of active galactic nuclei (AGN) has been detected from gamma-ray energies to radio wavelengths. At high energies, such variability appears to be intrinsic to the sources themselves. However, at radio wavelengths, brightness temperatures as high as 1018 to 1021 K are encountered if the IDV is intrinsic to the source. We discuss here the accumulating evidence showing that, at radio wavelengths where the highest brightness temperatures are encountered, interstellar scintillation (ISS) is the principal mechanism causing IDV. While ISS reduces the implied brightness temperatures, they still remain uncomfortably high.
Conservation efforts use scientific data to provide an adaptive framework wherein habitat and wildlife sustainability can co-exist with human activities. Good science informs decision-makers and facilitates the development of successful conservation approaches. However, conservation concerns for the dugong Dugong dugon in South-east Asia are sufficiently urgent that action must be taken quickly, even though science has not provided complete answers to critical questions. In Johor, Malaysia, aerial surveys were conducted to assess dugong numbers, dugong high-use areas and overlap of dugong sightings with areas of seagrass. Dugong distribution included existing marine parks and locations where known conservation threats exist. We conclude that the Johor islands may represent a significant congregation site for dugongs in Peninsular Malaysia, with as many as 20 dugongs recorded in a single day. The existence of a marine park where the dugong sightings were most prominent is encouraging but only 38% of those sightings fell within the boundaries of the park. Anthropogenic threats need to be assessed and addressed prior to complex development activities such as dredging and coastal reclamation for tourism development in this critical area. We use this case to explore the concept of advancing species conservation through focused research and management, particularly where uncertainties exist because data are scarce.
We report the results of a successful 7-hour 1.4 GHz Very Long Baseline Interferometry (VLBI) experiment using two new stations, ASKAP-29 located in Western Australia and WARK12M located on the North Island of New Zealand. This was the first geodetic VLBI observing session with the participation of these new stations. We have determined the positions of ASKAP-29 and WARK12M. Random errors on position estimates are 150–200 mm for the vertical component and 40–50 mm for the horizontal component. Systematic errors caused by the unmodeled ionosphere path delay may reach 1.3 m for the vertical component.
This book was born out of passion, frustration, excitement and hope. Readers will perceive all these emotions throughout the following pages. If the hard-won lessons recounted here lead to improved conservation of some remarkable species and their ecosystems, we will have fulfilled our aim.
We have cumulatively spent well over a century studying the various members of the Order Sirenia. Our passions include learning about and trying to conserve manatees and dugongs. The word ‘unique’ has lost its force through inaccuracy and over-use, but we want to reclaim its original meaning here. The sirenians possess suites of morphological, ecological and physiological adaptations that allow them, truly, to hold a unique place in the animal kingdom. Although once a more diverse group, the sirenians are limited now to only four species, albeit with remarkably wide geographic ranges (especially the dugong). Reduced in numbers through much of that range, and with myriad threats to their long-term survival, the sirenians have nonetheless demonstrated tenacity and resilience, hopeful signs that they will persist, if given a chance.
Understanding the conservation status of species is very important because it is an indicator of the likelihood of their continuing to exist. In this chapter we first review the criteria used for designating the conservation status of sirenians. We then provide an overview of the methods used for estimating abundance and trends in population sizes. The remainder of the chapter provides an updated summary of findings and our assessment of the status of the extant sirenians. This assessment includes reviews of their status under various international agreements, population sizes and trends, major threats and pertinent conservation impediments and actions.
Criteria for Designating Conservation Status
The IUCN Red List of Threatened Species (Red List) produced by the Species Survival Commission (SSC) of the International Union for Conservation of Nature (IUCN) is the best-known global conservation status listing and ranking system (IUCN 2009). In 2005 the World Conservation Congress passed a resolution mandating the use of the Red List for national legislation, international conventions, conservation planning and scientific research (IUCN 2005).
In 2008 a US federal court judge ruled that the Defense Department’s plans to construct an offshore marine airbase on the island of Okinawa, Japan contravened the US National Historic Preservation Act of 1966 (Tanji 2008). The rationale for the court’s decision, known as Dugong v. Gates, was that construction plans for the base failed to protect the dugong, one of the animals that are the subjects of this book. The dugong is listed as critically endangered by the Japanese Ministry of the Environment and as a National Monument on the Japanese Register of Cultural Properties because of its high cultural value to the people of Okinawa. In 2005 a companion court case (Dugong v. Rumsfeld) had established the legitimacy of declaring an animal to be a historically significant ‘property’ under US legislation, ensuring that the US National Historic Preservation Act of 1966 applied.
The outcome of these court cases does not guarantee the future of the dugong in Japan, where it is subject to multiple threats in addition to the airbase (Marsh et al. 2002; Ikeda and Mukai 2012; Chapter 8). Indeed, the court decision seems unlikely to prevent the construction of the airbase.