bluuebunny/crossref_metadata_2025_split huggingface dataset:
Search for Bursts of Ultra-High-Energy Photons from Astrophysical Sources
Authors: Ciampa D. , Clay R. W. 
Published: July 2016

AbstractThe Buckland Park air shower array has been used for some time as an ultra-high-energy gamma-ray telescope operating at photon energies of about 1015 eV. Other such telescopes have reported apparent bursts of events from astrophysical objects under study. We report here searches for UHE bursts from 14 southern hemisphere objects studied in our UHE programme. No conclusive evidence has been found for any UHE burst activity from these sources in the period 1986-1988. There is possible evidence for activity associated with 1700-377 and SN1987A.
History and Propaganda in Astronomy
Authors: Christiansen W. N. 
Published: July 2016

‘History is Bunk’ said Henry Ford. He was exaggerating but it is well recognized that the connection between history and truth is tenuous. Even very recent history dependent on human memory is notoriously unreliable despite the intention of the historian to tell the truth.In radio astronomy we are fortunate in having a dedicated historian-astronomer by the name of Woody Sullivan who has spent years in interviewing and reinterviewing astronomers to find out the real facts about the early years of the subject. Because of Sullivan’s work (e.g. Sullivan 1988) and because so many of my former colleagues have written histories of the period I felt very doubtful about adding my piece to the saga when asked to do so. However, I did accept the invitation to do so after I had read a statement about radio astronomy written by our usually very well informed Minister for Science, Barry Jones (Jones 1987). This statement which I shall quote later is an example of what we may call popular history.
Period Changes in the X-ray Pulsar GX 1 + 4
Authors: Greenhill J. G. , Giles A. B. , Sharma D. P. , Warren D. M. , Sprent A. , Emery M. W. , Dieters S. W. B. , Fenton K. B. , Sood R. K. , Waldron L. M. , Thomas J. A. , Mace O. , Manchanda R. K. 
Published: July 2016

AbstractThe binary X-ray source GX 1 + 4 was observed during a balloon flight in 1986, November. The source was in a relatively high intensity state. Time analysis of the data shows that the pulsation period was 111.8 ± 1.0 s indicating that one or more episodes of spin-down occurred between 1980 and 1986. Folded pulse profiles are very broad with an indication of a notch at the peak. Evidence has been found for a correlation between hard X-ray intensity and phase of the proposed 304 day orbital period. The time averaged intensity since 1980 is an order of magnitude lower than during the 1970’s. A survey of the post 1980 data shows that several reversals of the period derivative have occurred. Spin-up at the rates typical of the 1970’s has been followed by a dramatic spin-down episode with dP/dt>2.4 × 10−7 s/s.
A Search for and Optical Pulsar in SN 1987A using Real-Time FFT Techniques
Authors: Kroupa P. , Blair D. G. 
Published: July 2016

AbstractIt is shown that real-time FFT techniques used in conjunction with a small telescope can yield useful sensitivity. The suitability of the Crab pulsar as a calibrator is assessed. The mains frequency modulation in the night sky above Perth is clearly discerned, with several harmonics. Detectable signal modulation limits for SN 1987A are derived as a function of frequency in the range 10-2000 Hz.
A Southern Galactic Survey at 843 MHz
Authors: Whiteoak J. B. Z. , Large M. I. , Cram L. E. , Piestryzynski B. 
Published: July 2016

AbstractThe Molonglo Observatory Synthesis Telescope (MOST), operating at 843 MHz, is currently surveying the southern galactic plane (245° <l<360°, −1.5° ≤b≤ +1.5°). The resulting maps provide images of the radio continuum with a synthesised beamwidth of 43′′ × 43′′ cosec δ and a noise level of about 1mJy. The survey involves 12-hour synthesis observations of over four hundred fields on a predefined set of field centres. About half the fields have been observed to date, and the survey is scheduled for completion in 1990. A noteable feature in many of the fields is the occurrence of widespread diffuse filamentary structure, in addition to the expected supernova remants and HII regions.
G357.7-0.1—a Double-lobed Radio Source?
Authors: Caswell J. L. , Kesteven M. J. , Bedding T. R. , Turtle A. J. 
Published: July 2016

AbstractThe radio source G357.7-0.1 has commonly been regarded as a galactic supernova remnant; alternative interpretations have concentrated on the pronounced brightness gradient along its major axis. Analysis of our new map shows that this brightness gradient masks an even more crucial characteristic – symmetry about the centre – the key to a totally different interpretation.
A High-Resolution Acousto-Optical Spectrograph Suitable for CO Observations of Dark Clouds
Authors: Wang Jing-sheng , Robinson B. J. , Huang Geng-chen , Otrupcek Robina E. 
Published: July 2016

AbstractAn acousto-optical spectrograph (AOS) with a high spectral resolution of 28 kHz has been developed for spectral line observations of objects, such as dark clouds, where the line-widths are low. It has been mounted on the 4-m-diameter millimetre-wave telescope at CSIRO Division of Radiophysics at Epping, NSW and successfully tested using 115 GHz Co observations of a sample of southern dark clouds. At 115 GHz the velocity resolution is 0.07 km s-1.
What are IRAS Galaxies? An Optical Answer
Authors: Meadows V. S. , Allen D. A. , Norris R. P. , Roche P. F. 
Published: July 2016

AbstractA survey of the optical spectra of IRAS galaxies, made with the AAT, has shown that the majority have strong emission lines. Ratios of the emission lines have been plotted on the Veilleux-Osterbrock diagram ([O III]/Hβ against [N II]/Hα); this shows that the IRAS galaxies comprise several classes. In our sample the majority appear to be starburst galaxies, but Seyfert, Liner and narrow-line galaxies are also represented. Co-added spectra of the galaxy classes are presented. On the basis of optical spectroscopy, it appears that the starburst phenomenon is capable of generating luminosities exceeding 1012L⊙.
2152–69: The First Image from the Australia Telescope
Authors: Norris R. P. , Kesteven M. J. , Sramek R. A. , Wilson W. E. , Brooks J. W. , Calabretta M. R. , Ekers R. D. , Nelson G. J. , Sinclair M. W. , Young A. C. 
Published: July 2016

AbstractAlthough only three antennas of the Australia Telescope Compact Array are currently operational, we have made use of the technique of bandwidth synthesis to make an image of the radio galaxy 2152 – 69. The three baselines were used to observe the source at three different frequencies, effectively resulting in nine baselines, which have been used to produce an image with a surprisingly high dynamic range, and with a slightly higher resolution than any existing image.The production of such a worthwhile result, despite being made with a small subset of the capabilities of the Australia Telescope, bodes well for the future operation of the instrument.
Enhanced Cosmic Ray Diurnal Variations in Mawson and Hobart Neutron Monitor and Underground Data Records
Authors: Duldig M. L. , Humble J. E. 
Published: July 2016

AbstractAnalysis of surface and underground detector data from Mawson and Hobart for the period 1982 to 1988 has revealed a number of episodes of enhanced diurnal variation lasting more than 5 days. A preliminary study of these enhancements shows that variations in the rigidity spectrum and in the upper limiting rigidity must be present to explain the phenomenon.
The Asteroidal Impact Rate upon the Terrestrial Planets: An Update
Authors: Olsson-Steel Duncan 
Published: July 2016

AbstractThe probability of a collision with each of the terrestrial planets due to each of the Aten-Apollo-Amor asteroids discovered through to 1989 May is calculated; the range of possible impact velocities is also given in each case. For Mercury there are eight possible impactors known, with a mean collision probability of 1.30 × 10−9 per year; for Venus, the 32 planet-crossing asteroids give a mean collision probability of 9.63 × l0−9 per year; for the Earth the corresponding figures are 65 and 6.93 × 10−9 per year; and for Mars, 116 and 3.41 × 10−10 per year. The rate for Mars does not include the full range of Mars-crossers (i.e. those of 1.30<perihelion distance <1.67 AU are not included here), and for the interior planets any undiscovered population of asteroids would also alter the mean probability of an impact.
Wallal: The 1922 Eclipse Expedition
Authors: Burman R. R. , Jeffery P. M. 
Published: July 2016

AbstractOn 1922 August 20, a 20-strong scientific team, together with a naval party of 10, left Fremantle on one of the major scientific expeditions in Western Australian history. After picking up further personnel at Broome, the party proceeded to the isolated post and telegraph station of Wallal on the northern coast of Western Australia. Their task was to measure with great care the deflection of starlight by the Sun during the total solar eclipse of 1922 September 21. Specially designed photographic equipment of very high quality was used and meteorological conditions were excellent. As a result, measurements were obtained for well over a hundred stars.
The Business of Science
Authors: Cole T. W. 
Published: July 2016

In science we have good, successful laboratories and scientists and we also have wasteful, inefficient and unproductive ones. The differences are not matters of chance.
It is not an accident that just one Cambridge College, Trinity, has achieved more Nobel Prizes than all of Japan. There was something in common amongst the Nobel prize winners Todd, Adrian, Perutz, Bragg, Crick, Ryle, Hewish and Mott that I was fortunate enough to meet and, in some cases, get to know well. Of course there was the personal and intellectual calibre of these people, their drive and determination. But also, there was the laboratory culture within which they worked, a culture still benefiting from the influence of Maxwell, Thomson and Rutherford.
Radio Observations of the Einstein Deep X-ray Field in Pavo
Authors: Bedding T. R. , Turtle A. J. 
Published: July 2016

AbstractThe most sensitive X-ray survey available is a deep exposure made by theEinstein Observatoryof a 40 arcmin field in the southern constellation of Pavo. This survey revealed 33 X-ray sources, most of which were optically identified with quasars. Here, we report radio observations of the Pavo region at 843 MHz made with the Molonglo Observatory Synthesis Telescope. Eight overlapping fields were combined to produce the most sensitive radio map of the region to date, revealing 33 radio sources above a flux density of 2.4 mJy. Only one of these radio sources corresponded to an X-ray object: a quasar atz= 1.13. We also used the Parkes-Tidbinbilla Interferometer, at 2.29 GHz and 8.41 GHz, to observe some of the stronger radio sources.From these multi-wavelength observations of the Pavo field it is apparent that, to the sensitivity of the surveys involved, (i) there is little correlation between X-ray and radio detections, and (ii) most of the X-ray sources have optical counterparts while few of the radio ones do, and (iii) there is some confirmation that X-ray emission is higher for objects with flat radio spectra (i.e., a dominant core) than for steep spectrum sources.
Non-constant Superluminal Velocities in AGN
Authors: Coleman Colin S. 
Published: July 2016

AbstractLarge apparent superluminal velocities are observed in nuclear jets in Active Galaxies, indicating the presence of relativistic velocities almost along the line of sight. If the flow is well collimated, as suggested by the large scale radio structure, the inferred alignment leads to difficulties with source statistics. Here a modification of the usual relativistic beam model is proposed, in which the jet is assumed to contain azimuthal (swirling) flow. Perturbation analysis is used to show that the jet is unstable to a Kelvin-Helmholtz helical standing wave, the wavelength of which increases without bound in the limit of vanishing swirl. This instability may cause a cylindrical jet to follow a helical path in space, thereby reducing the implied alignment of a superluminal source, and providing a natural interpretation of non-constant superluminal velocities.
The Megamaser Galaxy III Zw 35
Authors: Chapman Jessica M. , Staveley-Smith L. , Axon D. J. , Unger S. W. , Cohen R. J. , Pedlar A. , Davies R. D. 
Published: July 2016

AbstractIII Zw 35 is a pair of galaxies characterised by intense OH maser emission, and powerful far-infrared and radio continuum. We have made a detailed study of the galaxy pair based on optical, infrared and radio observations. The brighter northern component is identified as a LINER or Seyfert galaxy and contains an active nuclear region from which radio continuum, OH maser and thermal dust emission are detected. We propose that the northern component has a compact active nucleus deeply embedded in an obscured region of diameter ~ 210 pc within which enhanced star-formation occurs. The lower luminosity, southern component is of low mass and is undergoing starburst activity over an extended region of diameter ~ 5.5 kpc. The origin of the starburst and non-thermal activity appears to be an interaction between the two components.
Starbursts in Ring and Irregular Galaxies
Authors: McIntyre V. J. , Zealey W. J. 
Published: July 2016

AbstractThis paper presents the current status of a Ph.D. project undertaken to search for extended-scale bursts of star formation (> 1 kpc) in irregular and collisionally produced ring galaxies, principally in the southern half of the sky. Results of recent 8.4 GHz radio continuum observations and UBVRI CCD imaging of some of the program galaxies are presented.
Radar and Spacecraft Ranging to Mercury between 1966 and 1988
Authors: Anderson John D. , Slade Martin A. , Jurgens Raymond F. , Lau Eunice L. , Newhall X. X. , Standish E. Myles 
Published: July 2016

AbstractImproved solutions have been obtained for the orbit and equatorial cross-section of Mercury using radar ranging data spanning 22 years. These data have yielded new results on the precession of Mercury’s perihelion and better limits on a possible time variation in the gravitational constant G.
Unneutralised Currents in Solar Flares
Authors: Melrose D. B. 
Published: July 2016

AbstractObservations of the vector magnetic field imply that there is a net current flowing through the corona, and there is also evidence that this current is directly related to flares. It is argued that if the currents are unneutralised, then this requires a radical rethinking of several widely accepted ideas on solar magnetic fields and their role in solar flares.
The Downturn in Solar Activity during Solar Cycles 5 and 6
Authors: Murphy J. O. 
Published: July 2016

AbstractThe atmospheric 14C record, the corresponding WM values derived from a carbon reservoir model, auroral numbers and the Zurich relative annual sunspot numbers all demonstrate a substantial downturn in solar activity for the duration of solar cycles 5 and 6. This reduction is also imbedded in some dendrochronological proxy data sets, which describe an annual index radial growth rate for trees at high-altitude sites. A significant lagged correlation can exist between tree-ring indices and the 11–year solar cycle during periods of high solar activity, a feature which is not evident during quiescent periods.
Optical and Near-infrared Observations of Supernova 1987A
Authors: Spyromilio Jason 
Published: July 2016

AbstractWe present observational results obtained during the first three years following the explosion of Supernova 1987 A. We discuss aspects of the optical and near infrared spectra as well as results from spectropolarimetric observations. The observations of the circumstellar and interstellar medium are also briefly discussed.
The Japanese National Large Telescope
Authors: Kogure Tomakazu , Kodaira Keiichi 
Published: July 2016

AbstractThe Japanese National Large Telescope is an 8-metre class optical-infrared reflector with a monolithic thin meniscus mirror, to be constructed at the Mauna Kea summit, Hawaii. The JNLT will be characterised by high quality performance in the optical and infrared regions, achieved by adopting new technologies such as active mirror support, fast optics and a thermally controlled dome. In particular, high infrared qualities are regarded as the most important characteristics among various design goals.The JNLT project is now close to the final study phase before construction. This paper reviews the scientific motivations and the special technical features of the JNLT. Finally, the promotion of international collaboration around the JNLT is emphasised.
The Geometry of the SMC
Authors: Gardiner L. T. , Hatzidimitriou D. , Hawkins M. R. S. 
Published: July 2016

AbstractWe have undertaken a study of the 3-D spatial distribution of the older (τ ≥ 1–2 Gyr) stellar population lying beyond ~ 2 kpc in projected radial distance from the centre of the SMC. The study will eventually cover 120 square degrees including six overlapping Schmidt fields. Here we present the results from an area of 80 square degrees including the western, northern and north-eastern outer parts of the SMC.
Global Magnetic Structure In Spiral Galaxies
Authors: Spencer S. J. 
Published: July 2016

AbstractGlobal magnetic structure has been inferred in spiral galaxies from radio and optical observations. The author has developed a three dimensional, quasi-global kinematic dynamo model which demonstrates the possibility of maintaining large-scale magnetic fields by the αω mechanism. Analytical expressions for large-scale galactic magnetic fields near temporal steady states have been derived. Illustrations of the spatial distribution of vector and absolute large-scale magnetic field strength are presented. When coupled with observations this model may help in understanding the maintenance and morphologies inferred for disk and halo global magnetic fields in spiral galaxies.
Photometric and Spectroscopic Analyses of Cool HdC Stars
Authors: Cottrell P. L. , Lawson W. A. 
Published: July 2016

AbstractA photometric and spectroscopic survey of many of the cool H-deficient Carbon (HdC) stars, including the R Coronae Borealis (RCB) stars, has been undertaken. For the RCB stars we have data on both the low amplitude photometric variations at maximum light and the major declines, the latter being the most distinguishing feature between the RCB and HdC stars.The photometric data at maximum light have been analysed using the Lomb-Scargle Fourier method, which has revealed many significant periodicities. From estimates of the temperature of these stars, an observational period-temperature diagram can be compared with theoretical models. These models have also enabled us to determine the evolutionary lifetime of these stars for comparison with observational parameters, e.g., period changes.Over the last several years we have photoelectrically covered the declines (and the recovery from some of these declines) of a number of RCB stars, from which we have been able to characterise two extreme types of decline behaviour. In addition, we have for the very first time spectroscopically recorded the initial decline phase of one (the prototype, R CrB) of these stars.
Automated Computation of General Perturbations for the Flora Asteroidal Group
Authors: He M. F. , Zhangjie  
Published: July 2016

AbstractThe general perturbations of the asteroids of the Flora group (975″ < n < 1150″, n - the mean daily motion) due to Jupiter have been automatically computed on an IBM 4341 computer with the Hansen method by manipulating Broucke’s Symbolic Poisson Series Processor, and the results have been compared with that computed previously with the Bohlin group method.
A Coudé Auxiliary Feed for the AAT: a Focus for International Co-operation in Optical Astronomy
Authors: Gillingham P. , Pettini M. , Bessell M. , Cram L. , Ogura K. 
Published: July 2016

AbstractIn 1988, a very powerful and versatile coudé echelle spectrograph was installed at the Anglo-Australian Telescope. Since then it has been winning about 30% of AAT time and has been highly productive scientifically. Therefore, using a coudé auxiliary telescope (CAT) to give the spectrograph more use and to free the AAT for other work is a very attractive possibility, particularly if the CAT can give a sensitivity similar to that obtained with the 3.9-metre telescope. While a conventional CAT with such performance would be very expensive, a much cheaper instrument should approach this goal, at least for high resolution spectroscopy. Even so, the cost could not be met in a reasonable time within the AAO’s budget; hence, additional international collaboration is being sought.
The Mt John CCD System: Status and First Scientific Results
Authors: Tobin William 
Published: July 2016

AbstractA Photometrics CCD system containing a TH7882 chip has been in use at Mt John since 1989 October for imaging photometry. Extra control software has increased observing ease and image-header information. Photometrically the system appears to be performing satisfactorily. The blue helium star LSS 99 showed no variation exceeding ~ 1% over 40 min of observation. The blue eclipsing binary HV 1761 in the Small Magellanic Cloud is found to have approximately equal components.
Communicating Space Science to the Public
Authors: Dougherty Kerrie A. , James Matthew L. 
Published: July 2016

AbstractA version of this paper was originally presented at the Fifth National Space Engineering Symposium at Canberra in November 1989. A copy of the full paper will be found in the text of the Proceedings. It is presented here because the authors believe that the issues raised and strategies suggested are as relevant to the astronomical community as they are to other areas of space science and technology.
The Origin and Composition of Pluto and Charon: Chemically Uniform Models
Authors: Prentice A.J.R. 
Published: July 2016

AbstractObservations of the Pluto-Charon system using the Hubble Space Telescope are soon to provide another test of the modern Laplacian theory of solar system origin. According to this theory, Pluto, Charon and Neptune’s moon Triton are condensed remnants of the gas ring which was shed by the proto-solar cloud at Neptune’s orbit, and from which Neptune formed. Each body should have the same bulk chemical composition provided that the influence of secondary events such as physical collision can be neglected. Here we report a model for the time-dependent, surface-catalysed production of CH4, solid carbon C(s) and CO2 within the outer layers of the proto-solar cloud. This model is used to determine the condensate mix which best fits the Voyager 2 spacecraft measurements of Triton’s mean density. We suggest that Triton is a chemically homogeneous structure consisting, by mass, of 44.2% anhydrous rock, 2.1% graphite, 33.0% water ice and 20.7% dry ice (i.e., solid CO2 ice, of which a fraction nearly 2/3 is present as the clathrate hydrate CO2·5.75 H2O). On the basis of this composition, the individual mean densities of Pluto and Charon are predicted to be 2.02 ± 0.02 g/cm3 and 1.94 ± 0.02 g/cm3, respectively, assuming a mean surface temperature of 35 K. The mean density of the combined system is predicted to be 2.01 ± 0.02 g/cm3.