bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intelligent Fault Diagnosis at the Australia Telescope
Authors: Landau Robert 
Published: July 2016

AbstractThe Fault Diagnosis Expert System for the Australia Telescope analyses ~12000 items of monitor data every minute that report the health and stability of specific components and signal pathways in the array. These data are divided into signatures which are matched against signatures of known failure modes to diagnose problems with the array. Knowledge about many of the failures is acquired by generating them in earlier tests. The system keeps a six-hour history of the detailed behaviour of all monitor data as well as the visibilities. It archives the data in half-hour intervals, characterising the interval with a small set of robust statistical estimators. An interactive graphical user interface allows the simultaneous display of twenty-four histories of either the 6-hour data or one week of the characterised data, together with options for plotting one history against another and for calculating their robust regression.
A Complete Sample of Southern Radio Sources: Radio, Optical and X-ray Properties
Authors: Morganti R. , Tadhunter C. N. , Fosbury R. A. E. , Oosterloo T. , Danziger I. J. , Alighieri S. di Serego , Siebert J. , Brinkmann W. 
Published: July 2016

AbstractRadio, optical and X-ray observations of a complete flux-limited sample of southern bright radio sources have been analysed to investigate beaming and orientation effects in the different wavebands. We conclude that, in addition to beamed optical and radio components, there is evidence for anisotropic X-ray emission.
Possible Connection between Large-scale Structures
Authors: Di Nella H. , Paturel G. 
Published: July 2016

AbstractFrom the Lyon-Meudon Extragalactic Database (LEDA) we constructed a sample of 27000 galaxies with radial velocities smaller than 15 000 kms−1. From this first sample we selected the 5683 largest galaxies, which constitute a sample complete up to the diameter limit D25 = 1·6′. This sub-sample has been used to search for the most populated plane. The result is that the plane defined by the pole (l = 52°; b= 16°) contains twice as many galaxies as would be found for randomly distributed galaxies. This plane is not far from the supergalactic plane. The distribution of galaxies in this plane has been studied by using the radial velocity as an estimate of the distance. An excess of galaxies appears at a distance of about 70 Mpc. We discuss the reality of this density enhancement which could result from selection effects.
Variability of Methanol Masers
Authors: Caswell J. L. , Vaile R. A. , Ellingsen S.P. 
Published: July 2016

AbstractSites of recent star formation often radiate strong maser emission from methanol transitions near 6-6 and 12 GHz. We have studied many of these masers over several years and find that intensity variations are common on both transitions. We present observations which demonstrate marked variability in 48 sources. We explore the characteristics of the variability and find it to be typically quasi-periodic, on a timescale of between a month and several years. The amplitude of the variation is most commonly less than a factor of two, but can reach factors of ten. The variability of different features in a source is usually independent. Variability of features seen at both 6·6 and 12 GHz is sometimes correlated, with larger amplitudes usually seen at 12 GHz. A likely inference is that variations are occasionally due to a change in the pump rate throughout the masing region, but most are consistent with a change in the masing path length due to large-scale motions. In addition, it is likely that the majority of 6·6-GHz masers are saturated whereas the 12-GHz masers may be somewhat less saturated.
Do We Expect to See Young Pulsars outside Their Parent Shells?
Authors: Gaensler B. M. , Johnston Simon 
Published: July 2016

AbstractA recent study has indicated that a substantial fraction of young pulsars born in supernovae have travelled outside the boundaries of their corresponding shell supernova remnants. A simple model suggests that this should not be the case, implying either that some postulated pulsar/remnant associations are false, or that pulsars are particularly difficult to detect until they have emerged from their remnants.
Seeing Measurements at Freeling Heights and Siding Spring Observatory
Authors: Wood P. R. , Rodgers A. W. , Russell K. S. 
Published: July 2016

AbstractA low-cost differential image motion monitor (DIMM), consisting of an 11-inch Celestron, an SBIG ST-4 autoguiding CCD camera and a PC, is described. Two such systems were used during June–July and November–December 1993 to make near-simultaneous seeing measurements at Freeling Heights in the Northern Flinders Ranges and at Siding Spring Observatory. The results of these campaigns show that the seeing-distribution is generally similar at both sites, with the most common seeing value being ~l·2″. Siding Spring does, however, have slightly more bad seeing (>2″) than Freeling Heights. Weather records from Arkaroola Resort (15 km south of Freeling Heights) indicate that there is ~15% less cloud cover at Freeling Heights than at Siding Spring. Episodes of rapid seeing deterioration at Siding Spring in winter are shown to coincide with warm air masses crossing the mountain.
Connecting a Star’s Convection Zone with its Corona
Authors: Galloway D. J. , Jones C. A. 
Published: July 2016

AbstractThis paper discusses problems which have as their uniting theme the need to understand the coupling between a stellar convection zone and a magnetically dominated corona above it. Interest is concentrated on how the convection drives the atmosphere above, loading it with the currents that give rise to flares and other forms of coronal activity. The role of boundary conditions appears to be crucial, suggesting that a global understanding of the magnetic field system is necessary to explain what is observed in the corona. Calculations are presented which suggest that currents flowing up a flux rope return not in the immediate vicinity of the rope but rather in an alternative flux concentration located some distance away.
Preliminary Results of a Survey of Ultracompact H II Regions
Authors: Walsh A. J. , Hyland A. R. , Robinson G. , Bourke T. L. , James S. D. 
Published: July 2016

AbstractUltracompact H II regions are small, dense regions of ionised gas surrounding high-mass stars which are still embedded in their natal molecular clouds. A survey of such regions has been commenced in an attempt to improve our understanding of the processes of high-mass star formation. The initial stages of the survey have involved selection of likely candidates from the IRAS Point Source Catalogue, correlation with radio continuum emission at 4·85 GHz and subsequent observations of methanol maser emission at 6·668 GHz. Preliminary results of the methanol maser survey are given.
Prospects for Coordinated Observations with XTE
Authors: Giles A. B. , Jahoda K. , Swank J. H. , Zhang W. 
Published: July 2016

AbstractThe X-ray Timing Explorer (XTE) is a NASA satellite designed to perform high-time-resolution studies of known X-ray sources. The two main experiments are a large-area proportional counter array (PCA) from the Goddard Space Flight Center (GSFC) and a high-energy X-ray timing experiment (HEXTE) from the University of California at San Diego (UCSD). The PCA data is processed by an electronic data system (EDS) built by the Massachusetts Institute of Technology (MIT) that performs many parallel processing analysis functions for on-board evaluation and data compression. MIT also provide an all-sky monitor (ASM) experiment so that XTE can be slewed rapidly to new transient sources. The spacecraft provides a mean science telemetry rate for the PCA of ~20 kilobits per second (kbps), with bursts to 256 kbps for durations of 30 minutes. Photons are tagged to 1 μs and absolute timing should be better than 100 μs. XTE is due for launch in late August 1995 and the first NASA Research Announcement (NRA) is due out in January 1995. This paper summarises XTE’s performance and then discusses the interactive and flexible operations of the satellite and some of the science it can do. These features should make XTE a productive spacecraft for coordinated observation programs.
Xvoigt: An Interactive Absorption Line Fitting Program for the X Window System
Authors: Max David P. , Bailey Geoff 
Published: July 2016

AbstractWe have developed an easy-to-use, mouse-driven program for the interactive fitting of interstellar absorption lines in high-resolution astronomical spectra. The program, Xvoigt, gives values for the column density and velocity dispersion of the absorbing clouds. It runs under the popular X Window system available on most workstations, and offers significant enhancements over existing profile-fitting software. Xvoigt can be an important adjunct to automatic programs for fitting absorption lines in low to moderate signal-to-noise QSO or other spectra, and is ideal for demonstrating the details and difficulties of absorption line analysis.
Installation of the J. L. Sersic Astronomical Observatory at 78° South
Authors: Recabarren Pablo , Mosconi Mirta , Lambas Diego García , Dellizzotti Juan , Ozu Sheiko , Hutka Julio 
Published: July 2016

AbstractIn 1994 December we installed a Celestron CG11 Telescope at Belgrano Base (previously called Belgrano II) for site seeing measurements and variable star observations. We describe the project, logistics, installation and working environment. We present the first quantitative observations of astronomical seeing conditions at Belgrano Base.
Magnetic Braking and Its Implication for CV Evolution
Authors: Wickramasinghe Dayal T. , Li Jianke , Wu Kinwah 
Published: July 2016

AbstractWe review the models of magnetic braking for synchronously rotating magnetic cataclysmic variables, and discuss the implications of magnetic braking for orbital evolution and the upper limit to the magnetic fields (about 70 MG) of the observed AM Herculis systems.
Some Intrinsic Properties of Parsec-scale Radio Jets
Authors: Tingay Steven J. 
Published: July 2016

AbstractA simple model for estimating the intrinsic flow direction and speed in the parsec-scale jets associated with extragalactic radio sources is presented. In this model, radio source brightness asymmetries are attributed to the apparent amplification caused when a relativistic jet of radiating material is somewhat aligned with the observers line of sight. The knots of emission commonly seen in parsec-scale radio jets are interpreted as shocks in the relativistic fluid.
The Large-scale Distribution of Radio Sources
Authors: Drinkwater Michael J. , Schmidt Robert W. 
Published: July 2016

AbstractWe have used a sample of 263 Parkes half-Jansky flat-spectrum radio sources to measure the spatial correlation function of radio galaxies and radio-loud quasars on scales up to 1000 h−1 Mpc. We do not detect any clustering in the sample. If any undetected clustering is described by a power-law spatial correlation function [ξ(r) = (r/r0)−1·8], we can rule out clustering with scales r0 ≥ 50 h−1 Mpc at the 99·9% confidence level. We have also used the sample to test for the ‘possible’ large concentration of quasars in the direction of the microwave background dipole found by Shaver (1987). There is no evidence for such a concentration in our data and we show that the earlier result was probably biased by the use of non-uniform image classifications.
Zeeman Doppler Imaging of Stars with the AAT
Authors: Carter Brad , Brown Steve , Donati Jean-François , Rees David , Semel Meir 
Published: July 2016

AbstractZeeman Doppler Imaging (ZDI) is a recent technique for measuring magnetic fields on rapidly rotating, active stars. ZDI employs spectropolarimetry taken at different rotational phases to derive information on the magnetic field distribution over the stellar surface. The Zeeman effect is used to identify the presence of a magnetic field, and variations in Doppler wavelength shifts across the rapidly rotating star allow fields to be resolved on different parts of the visible disk. Analysis of the spectra can be used to produce both thermal and surface magnetic images. ZDI requires very high S/N spectra to be acquired within a time interval short compared to the stellar rotation period. As a result, a large-aperture telescope is needed. Since an initial successful test in 1989, the 3·9 m Anglo-Australian Telescope has been used to obtain ZDI spectra of active stars of different evolutionary stages. The observations have concentrated on the K subgiant in the RSCVn system HR 1099 to monitor changes on this bright and active star. With the advent in 1991 of ZDI spectropolarimetry with the AAT échelle spectrograph, it has become possible to co-add the polarisation signature from the many magnetically sensitive lines recorded simultaneously. As a result, stellar magnetic field detections of unprecedented quality have been obtained. The aims of this paper are to briefly outline the principles of ZDI, describe the instrumental setup at the AAT and present some preliminary results from recent observations.
Education and Public Astronomy Programs at the Carter Observatory: An Overview
Authors: Orchiston W. , Dodd R. J. 
Published: July 2016

AbstractThis paper outlines the extensive range of public programs offered by the Carter Observatory, including ‘public nights’, new planetarium and audio-visual shows, displays, the Carter Memorial Lectures, the annual Astronomical Handbook and other publications, a monthly newspaper column and three monthly radio programs. It also deals with the Observatory’s involvement in undergraduate and postgraduate astronomy at Victoria University of Wellington, various adult education training programs, ‘Overnight Extravaganzas’, holiday programs, and the recent development of the Education Service in response to the introduction of an astronomy curriculum into schools throughout New Zealand. Some possible future developments in the public astronomy and education areas are also discussed.
Millimetre Observations of Protostellar Disks
Authors: Maddison Sarah T. 
Published: July 2016

AbstractI look briefly at protostellar environments and at what information can be gained from the millimetre waveband. A short overview of the theory of protostellar environments and evidence of disks will be followed by a more detailed review of recent publications of observations of protostellar halos/disks, specifically in 3 mm.
The Electric Field in Axisymmetric Pulsar Magnetospheres
Authors: Burman R. 
Published: July 2016

AbstractIn an earlier paper with the same title, I showed how knowledge of the non-corotational electric potential required to support particles in corotation with the star can be used to deduce the global qualitative forms that the potential can take in axisymmetric pulsar magnetospheres, in the absence of outflowing particles. Those arguments will now be combined with work on the outflow zone to deduce qualitative features of the potential structure in the MRW2 model.
A 3072 Channel Surface Acoustic Wave Spectrum Analyser
Authors: Ellis G. R. A. , Hall P. J. 
Published: July 2016

AbstractA spectrum analyser based on SAW (surface acoustic wave) devices has been developed for Jupiter, solar and pulsar observations. It has an overall frequency range of 100 MHz and a frequency resolution of 30 kHz. A complete spectrum is produced every 80 μs. It is initially being used with a 4000 dipole broadband array in the frequency range 30-130 MHz and for Jupiter observations from 8-38 MHz.
An Emission Line Model for AM Herculis Systems: Application to E1405-451
Authors: Ferrario Lilia , Wickramasinghe D. T. , Tuohy I. R. 
Published: July 2016

AbstractThe optical spectra of the AM Herculis binaries are characterized by extremely complex emission lines whose profiles can be resolved into at least three components which are formed in different regions of the accretion stream leading from the companion star towards the magnetic white dwarf. We present a theoretical model which localizes the formation region of the broad emission line component and provides information regarding the structure of this emitting region. In our model the particle trajectories are integrated in a Roche potential and the volume between the white dwarf and the companion has been divided into two different regimes of motion. In one region the gas escapes from the secondary near the inner Lagrange point and is accelerated along a straight line towards the white dwarf. In the other region the magnetic field is strong enought to divert the gas out of the orbital plane and to channel it towards the white dwarfs surface. The model has been used to interpret radial velocity and velocity dispersion data from the AM Herculis system E1405-451.
A Spectroscopic and Photometric Study of 1H0542-407: A New Magnetic Variable
Authors: Buckley D. A. H. , Tuohy I. R. 
Published: July 2016

AbstractWe report spectroscopic and photometric observations of the new DQ Hercuis system 1H0542-407, recently discovered by us to be the optical counterpart of a HEAO-1 X-ray source. Medium resolution spectroscopy using the AAT in the region λ3930 to λ4960 conducted over consecutive nights shows radial velocity variations at periods of ∼ 1910 s, consistent with the white dwarf rotation period, and 5.7 h, in agreement with the orbital period derived from our EXOSAT observations. The K semi-amplitude velocities are ∼ 50 and 20 km s-1 respectively, leading to a mass function f(M) = 3.3 ± 0.6 × 10-3M⊙ and an orbital inclination close to 20°. The emission line profiles are characterized by simple Gaussians whose FWHM vary at the rotation period. A time series analysis of high resolution photometry conducted on the ANU 2.3 metre telescope reveals the presence of several periodicities, including the orbital sidebands. The dominant sideband (Vr − Vo) arises from X-rays reprocessed in a region corotating at the orbital frequency. A model is developed for 1H0542-407 which indicates that the accretion disk is disrupted at ∼5Rwd by the primary’s magnetic field. The short period velocity variations arise within the magnetosphere. A white dwarf magnetic field strength of < ∼ 3 MG is implied.
The Structure and Size of Radio Galaxy 1308-441
Authors: Jones P. A. 
Published: July 2016

AbstractThe structure of the radio source 1308-441 has been determined with the Molonglo and Fleurs radio telescopes. The nuclear component has been identified with a magnitude 15 galaxy and an optical spectrum, obtained with the Anglo-Australian Telescope shows galactic absorption features with a redshift of 0.0515 but no emission lines. The radio image shows the nuclear component linked by a well defined bridge to diffuse lobes extending for 11 arcmin west and 6 arcmin east. The asymmetry is believed to be due to projection effects. The projected size is 670 kpc (Ho = 100 km s-1 Mpc-1). The bridge contains several peaks with one strong unresolved peak 90 kpc from the galaxy.
The Calamity of the Great Melbourne Telescope
Authors: Hyde W. Lewis 
Published: July 2016

Sir William Herschel and his sister, Caroline, had swept the skies over England as members of the court of George III. They had made amazing discoveries: a new planet in our solar system, the movement of the solar system with respect to the fixed stars, and hundreds of new nebulae and star clusters.Then Sir William’s son John swept the southern skies from Cape Town, South Africa (1834 to 1838), mapping and sketching many more stars and nebulae.
Recent Results on SN 1987A
Authors: Woosley S.E. , Pinto P.A. , Weaver T.A. 
Published: July 2016

AbstractSeveral critical issues recently raised by observations of SN 1987A are addressed. These include: 1) the evolution of the pre-supernova star, why it was blue, what its composition and core structure were; 2) the detailed isotopic composition of the ejecta; 3) why and to what extent the supernova composition was mixed in velocity space; 4) the interpretation of recently observed infrared lines, especially their profiles and the existence of red-shifted ‘wings’; and 5) what has become of the neutron star.
The Elusive Radio Source SN 1987A
Authors: Reynolds John E. , Livermore R.W. , Jauncey David L. , Preston Robert A. , Gulkis Samuel , Bartel Norbert 
Published: July 2016

AbstractFollowing 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).
New Developments in Theoretical Modelling of SN 1987A
Authors: Nomoto Ken’ichi , Shigeyama Toshikazu , Kumagai Shiomi , Hashimoto Masa-aki 
Published: July 2016

AbstractWe summarise recent developments in modelling SN 1987A including the progenitor’s evolution, explosive nucleosynthesis, optical, X- and γ-ray light curves, and dust formation. The distribution of heavy elements in the ejecta is inferred from the light curves. The pre-peak optical light curve as well as early emergence of X- and γ-ray indicate the mixing of 56Ni into the hydrogen-rich envelope. The plateau-like peak of the optical light curve is well reproduced if hydrogen is mixed into the deep core. The flat X-ray light curve observed by Ginga would be due to the clumpy structure of the core. The progenitor’s blue-red-blue evolution and nitrogen abundance suggest that the progenitor’s hydrogen-rich envelope had mass Menv = 7 − 11 M⊙ and was almost completely mixed.
Space Telescopes: an International Perspective
Authors: Tuohy Ian R 
Published: July 2016

AbstractThe purpose of this paper is to review current and planned Space Astronomy missions from an international perspective, with principal attention to the programs of the USA, Europe, Japan and the USSR. The review focusses on extra-solar astrophysics, and the capabilities and broad research objectives of numerous individual spacecraft are described. These collectively span more than seventeen decades in wavelength and thus provide an essential complement to ground-based astronomy. Many of the missions offer significant opportunities for Australian participation via three complementary routes. First through Guest Investigator programs analogous to that offered for the Hubble Space Telescope (HST). Second, through the proposed establishment of an Australian Space Astronomy Data Centre to gain access to archival data from HST and other missions (the creation of such an archival facility in Canada is highlighted as a pertinent example). Third, via the contribution of instrumentation or ground support services. This latter category includes the Radioastron VLBI mission for which an agreement with the USSR has already been signed. In addition, an unprecedented opportunity has arisen for Australia to provide a ground station for the Infrared Space Observatory (ISO), due to be launched by ESA in 1993. In return for providing this service, the Australian astronomical community would receive a guaranteed share of the ISO observing time during the two year mission. Finally, Australian astronomers have been invited to contribute an advanced All-sky X-ray Monitor for the Soviet Spectrum-X-Gamma mission in 1993. This opportunity, and also the Radioastron initiative, have arisen under the USSR-Australia Space Research Agreement signed in December 1987.
Search for Ultra-High-Energy Gamma-Rays from SN1987A
Authors: Bird D. J. , Ciampa D. , Clay R. W. 
Published: July 2016

AbstractWe report here a search of data recorded by the Buckland Park air shower array from the first year after the supernova and set an upper limit to the proton luminosity of SN1987A of 7.7 × 1040 ergs s−1.