bluuebunny/crossref_metadata_2025 huggingface dataset:
Very Narrow Band Interference Filters
Authors: Ramsay J. V.
Published: July 2016

In solar physics a need exists for filters which have very narrow passbands, ~0.01 nm or less. While Lyot-Öhman birefringent filters have been used particularly for investigations at the Hα line, the limited availability of the raw materials, especially calcite, have usually restricted these filters to passbands of ~ 0.025 nm or more. A possible alternative type of filter consists of a number of Fabry-Perot interferometers mounted one behind the other.
Anharmonic Oscillations of Massive Stars
Authors: Murphy J.O.
Published: July 2016

The equation of motion, derived from the basic Lagrangian equations for the conservation of momentum and the conservation of energy, for non-linear non-adiabatic radial oscillations of a pulsating star takes the form
Radio Observations of Seven Suggested Supernova Remnants
Authors: Milne D.K.
Published: July 2016

In a recent paper Aizu and Tabara list 36 radio sources classified as supernova remnants (SNR). Some of these identifications are based on low-resolution radio data and are consequently unreliable. Using the Parkes 210-foot radio telescope at 635, 1410 and 2650 MHz (beamwidth 31′, 15′ and 8′.4 respectively), E. R. Hill and the author observed the seven sources listed in Table I. Of these seven, there is close agreement with Aizu and Tabara’s data only in the last one (3C396.1), and we agree with the SNR classification, with certain reservations, for only three of these sources.
Cosmic Noise Intensities at Hectometre Wavelengths
Authors: Parthasarathy R.
Published: July 2016

The object of this contribution is to report the galactic background intensity at 2 and 3 MHz. The observation is an extension of earlier work which the noise temperatures at 50, 30, 20, 10 and 5 MHz were obtained at 65°N declination by means of identical antennas of beamwidth 70° between half-power points. As discussed in the earlier work, the temperatures were obtained separately in the ordinary and extraordinary modes, in order to account for the attenuation in the ionosphere.
Photoelectric Observations of Short-Period Cepheids in the Magellanic Clouds
Authors: Gascoigne S.C.B.
Published: July 2016

Two-colour photoelectric light curves have been obtained for 9 SMC and 7 LMC variables, with periods in the range 1.24-6.61 days. Because of crowding problems, satisfactory observations could be obtained only for cepheids in the outer parts of the Clouds. The LMC cepheids are in the vicinity of NGC 1805-1818, in a field studied at Herstmonceux. The majority of those in the SMC are immediately south of NGC 362.
Neutral Hydrogen Observations of NGC 5236
Authors: Lewis B.M.
Published: July 2016

NGC 5236 is the fourth galaxy beyond the local group to be investigated at Parkes. Most of the observations were made with a single-channel 21 cm line receiver, coupled to the 210 ft dish. The half-power beamwidth is 13´.5. Declination scans were made through the galaxy, and treated by methods already established for NGC 551, NGC 3002 and NGC 31093. The peak antenna temperature is 1.5°K.
The Inverse Compton Effect in Extra-Galactic Radio Sources
Authors: Johnston I. D. , Rothman G. P.
Published: July 2016

It was first pointed out by Hoyle et al. that quasars if they are indeed located at cosmological distances, must be characterized by an extraordinarily large radiation density : and therefore, though their optical and near infra-red spectra appear to be dominated by synchrotron radiation, any ultrarelativistic electron present must necessarily lose essentially all its energy by inverse Compton scattering. This would mean that, though quasars are emitting fantastic amounts of energy at optical frequencies, they must also be emitting many orders of magnitude more at X-ray and γ-ray frequencies. This paradox has been evaded by several specially constructed models (e.g. Rees and Sciama, Woltjer and Jukes); but the problem has not been removed in general.
A Theorem on Ray Trajectories
Authors: Westfold K.C.
Published: July 2016

The classical theorems on the intensity of radiation (e.g. Milne) depend on the geometry of rectilinear ray trajectories in uniform media. In particular, the theorem concerning the specific intensity I in a medium specified by an isotropic refractive index μ—that, where there are no gains due to emission or losses due to absorption or scattering, the quantity I/μ2 = constant—is proved by assuming that the medium consists of a series of regions of constant refractive index at whose plane interfaces the coefficients of reflection are zero. For these the geometry of the trajectories (Figure 1) is such that, by Snell’s law,
The X-ray Albedo from the Earth
Authors: Harries J.R. , Francey R.J.
Published: July 2016

An albedo X-ray flux from the Earth was observed by experiments which were flown on Skylark rockets during April 1967. The details of the flights and the equipment have been covered in a previous paper. The celestial X-rays observed from discrete sources are superimposed on a diffuse X-ray flux. Most measurements of this diffuse flux have taken the difference between the number of X-rays observed from an area of sky, which is thought to be free of sources, and the flux from the direction of the Earth. By assuming that there are no X-rays from the direction of the Earth, this method removes the high-energy charged-particle background which should be the same in both cases.
Cosmic-Ray Anisotropies as a Function of Time and Direction
Authors: Ables J.G.
Published: July 2016

The cosmic ray flux in the energy range 100 MeV/nucleon ≤ E ≤ 1 GeV/nucleon is remarkable for its high degree of isotropy. Observed deviations from isotropy seldom exceed a few per cent and are commonly much smaller. The mechanism responsible for this isotropy is presumed to be multiple, large-angle scattering of the charged cosmic ray particles by irregularities of the interplanetary magnetic field. While generally precluding any hope of discovering a source-related anisotropy of the flux in this energy range, it is just this strong interaction of the cosmic rays with the interplanetary medium that allows the study of the small observed anisotropies, both persistent and transient, to yield considerable information about the structure of the interplanetary medium (the solar wind and its entrapped magnetic field).
Corotating Forbush Decreases
Authors: McCracken K. G. , Palmer I.
Published: July 2016

A natural introduction to this topic is a brief discussion of two phenomena observable in interplanetary space near Earth—the energetic storm particle event (ESPE), and the recurrent Forbush decrease.
Correlation Between the Cosmic-ray Solar Daily Variation Underground and Geomagnetic Activity
Authors: Fenton A. G.
Published: July 2016

Since 1957, the University of Tasmania has operated cosmic-ray meson telescopes at an underground site near Hobart for the purpose of monitoring the intensity variations in the high energy component of the primary flux near the Earth. Details relating to the site, equipment, and meteorological influences on the observed intensity have been given previously. At a depth equivalent to 36m of water (36 m.w.e.), the equipment responds to an effective primary spectrum having a mean particle energy in the vicinity of 200 GeV and falling off rapidly at low energies, so that about 90% of the primaries have energy exceeding 50 GeV. The corresponding mean energy of response for surface muon telescopes at Hobart is about 25 GeV, while a neutron monitor at Hobart has a mean response at about 7 GeV.
A New Determination of Muon Directional Coupling Coefficients
Authors: Cooke D. J. , Fenton A. G.
Published: July 2016

Primary cosmic rays passing through the solar system carry with them valuable information about solar and astrophysical phenomena in the form of intensity and spectral variations. In order that this information be efficiently extracted from observations of the directional cosmic-ray flux at the surface of the Earth, it is essential to have accurate information available to enable the relating of the observed secondary cosmic-ray directions of motion and intensity to those outside the range of the disturbing terrestrial influences.
Observations of High-Energy X-Rays from Sagittarius
Authors: Clancy M. C.
Published: July 2016

During a recent balloon flight from Mildura, Australia, the region of the Galaxy between −10° < lII < +20°; −5° < bII< +5° was surveyed for high-energy X-rays of photon energy > 17 keV (λ < 0.7 Å) using an active collimation scintillation detector described elsewhere. The narrow opening angle of the telescope enables two sources to be resolved in this region of the sky. The position of one of these sources agrees well with the source GX3+1 observed at rocket wavelength by Bradt et al. while the other source is probably the same as that observed by Gursky et al. and designated GX−5.6. We present herein improved positional information for this latter source which hereafter will be designated GX354−5.
Temperature Fluctuations and Convective Modes in the Solar Photosphere
Authors: Wilson P. R.
Published: July 2016

Recently I have carried out a two-dimensional radiative-transfer analysis of the data given by Edmonds on centrelimb relative rms intensity fluctuations in terms of horizontal temperature fluctuations in the solar photosphere. Edmonds himself attempted an analysis of his data and found a ΔTrms which increased monotonically from about 300°K at unit mean optical depth (i.e. at a given physical depth) to 500°K at optical depth 3.
Power Spectral Analysis of Chromospheric Inhomogeneities
Authors: Cannon C. J.
Published: July 2016

In July 1967 and June 1968 observations of the central intensity variation in several chromospheric lines were obtained by P. R. Wilson and myself at Sacramento Peak Observatory, New Mexico using the 16-inch coronagraph coupled with the high-dispersion Littrow Spectrograph. Observations in the MgB lines (λ5184, 5173, 5167 Å) were obtained the first summer whilst the NaD lines (λ5889, 5896 Å) were studied in the second. Table I shows the mean heights in the solar atmosphere at which it is thought these lines are formed.
Hydrogen Alpha Profiles in Cepheids
Authors: Schmidt E. G.
Published: July 2016

Theoretical Hα profiles have been used by Rodgers and Bell (hereafter denoted by RB) to obtain the effective temperatures of several cepheid variable stars. They find that the profiles are sufficiently sensitive to temperature to enable them to determine temperatures which are accurate to within about 300°, while being insensitive to other factors such as gravity or the form of the temperature distribution in the model atmosphere.
A Thermal Source with Strong 1612 MHz OH Emission
Authors: Robinson B. J. , Goss W. M. , Manchester R. N.
Published: July 2016

During 1968 we have found at Parkes several types of emission in the lines of the 18 cm quadruplet of the ground-state OH molecule. This note describes a strong source of 1612 MHz emission near galactic longitude 331°.

OH emission was originally detected in the vicinity of HII regions, and a search of a large number of HII regions showed that about a third had associated OH emission. This type of emission is usually strongest at 1665 MHz, and is also seen at 1667 MHz and weakly on one of the satellite lines.
Time Variation in the Polarization of OH Emission from NGC 6334B
Authors: Goss W. M. , Robinson B. J. , Manchester R. N.
Published: July 2016

Time variations in both the NGC 6334 and Orion OH sources have been reported by the Berkeley group. The variations in NGC 6334 have been partially confirmed by the group at the Lincoln Laboratory, who show that the variations are confined to the southern source, NGC 6334B. These latter authors find variable components at —6.6 and —7.9 km/s at 1665 MHz and at —8.9 km/s at 1667 MHz. Both features at 1665 MHz appear to vary, both up and down, with time; during 1966 October the characteristic rise time was nine days or less. The Berkeley results show that the linear polarization was constant during a two-week period in 1965 October. The Lincoln Laboratory results from 1966 October to 1967 June show that both the degree and sense of circular polarization remain constant as the three features vary with time.
A Rediscussion of the Radio Spectrum of the Orion Nebula
Authors: Shaver P. A. , Mills B. Y.
Published: July 2016

The Orion Nebula is the best known and most often observed of the bright emission nebulae. However, the radio continuum spectrum of the nebula has been the subject of some misconception, particularly at low frequencies. A rediscussion is worthwhile as the spectrum has been used to derive an electron temperature for the nebula which is at variance with other determinations and carries important implications. Also some of the difficulties of measurement and problems of interpretation are relevant to similar investigations of other emission nebulae.
Forbidden Lines and Electron Temperatures in Gaseous Nebulae
Authors: Aller L. H. , Czyzak S. J.
Published: July 2016

Electron temperatures of compact gaseous nebulae such as planetaries may be derived from radio-frequency data combined with isophotic contours accurately corrected for resolution effects, from the continuum jump at the Balmer limit and other features of the nebular continuum, and from forbidden line ratios.
Temporal and Spectral Variations in the Amplitudes of Three Pulsars at 80 MHz
Authors: Slee O. B.
Published: July 2016

The radioheliograph at Culgoora has recently been used to investigate the interesting changes which take place in the amplitudes of the pulses from PSR 0950+08, 1133+16 and 1919+21. The experiments had two main objectives: (i) to investigate the temporal changes in the spectrum near 80 MHz; (ii) to search for periodicities in the pulse amplitudes with periods extending up to one or two minutes.
Pulsar Amplitude Variations
Authors: Wielebinski R.
Published: July 2016

Pulsars display a complicated pattern of amplitude variations. The scale of variations range from months through hours to sub-milliseconds. The purpose of this note is to present polarization data for CP 1919 and intensity distribution data for PSR 0833—45 which are relevant to pulse-to-pulse variations and the variation over periods of hours respectively.
Pencil-beam Observations of Fornax A, Virgo A, and Centaurus A at 408 MHz
Authors: Cameron M. J.
Published: July 2016

Radio contours are presented for Fornax A (NGC 1316), Virgo A (NGC 4486) and the central component of Centaurus A (NGC 5128). These three objects are intrinsically strong radio emitters identified with bright galaxies. The work forms part of a survey of all bright galaxies with the Molonglo cross down to a corrected total magnitude of 11m.0 with an extension down to photographic magnitude 12m.5 in an limited region of the sky.
The Over-estimation of the Flux Density of Weak Radio Sources
Authors: Murdoch H. S.
Published: July 2016

The over-estimation of the flux density of radio sources near the lower limit of a survey has often been considered in the past. The use of digital recording and analysis techniques now enables a quantitative approach to the problem. Monte Carlo techniques may be used to determine the error distribution, including any systematic bias.
Time Variation of the Radio Emission from Sco X-1
Authors: Ables J. G.
Published: July 2016

The radio object associated with Sco X—1 noted by Andrew and Purton has been observed at a wavelength of 6 cm with the 210 ft radio telescope at the Australian National Radio Observatory, Parkes. At this wavelength the half-power antenna beamwidth is 4′ arc.
Radiation Theory: Stark Broadening in the Two-level Approximation
Authors: Dyne R. J.
Published: July 2016

The study of line-broadening mechanisms puts at our disposal an extremely useful tool for the investigation of physical conditions in plasmas, both stellar and laboratory.
A Comparison of Radio-Frequency and Optical Studies of Selected Planetary Nebulae
Authors: Aller L. H.
Published: July 2016

The thermal radio-frequency emission, Ev, per unit volume per unit frequency interval may be computed (e.g. from equations given by Oster) and compared with the volume emissivity E(Hβ) in the optical Hβ transition.
Two Double Galaxy Systems
Authors: Lewis B. M.
Published: July 2016

It is generally assumed from an inspection of prints of non-magellanic spiral galaxies that all constituents, including the HI, are distributed with a large-scale circular symmetry in the plane of the galaxy. This assumption is supported by the expectation that any primordial asymmetry in the mass distribution would have disintegrated by the present epoch under the shearing effects of differential rotation into an approximately circularly symmetric ring. It is therefore surprising to find that the recent high-resolution studies of M 31, M 101, NGC 300 and our own galaxy all show that the HI centroid is significantly displaced from the nucleus. This is a sign that the HI distribution is markedly asymmetric.
The Normal Elliptical Galaxies
Authors: Freeman K. C.
Published: July 2016

About 13% of bright galaxies are ellipticals (21% SO, 64% Spiral and Im, 2% IO and peculiar). Their obvious features are the smooth luminosity distribution and the near absence of the bright blue stars, HII regions and dust that appear in spiral systems; there is probably very little star formation going on at present in E galaxies. I plan to discuss some of the dynamical and physical properties of these systems; although many of them are known radio sources, I will not be able to discuss their radio properties.
Positions of the Fundamental and Harmonic Sources of a Type II Solar Burst
Authors: Dulk G. A.
Published: July 2016

Type II solar bursts characteristically drift slowly from high to low frequencies at a rate of about 0.1 MHz/s, appear only at frequencies lower than 250 MHz, and frequently have harmonic structure, i.e. there are identifiable spectral features within the fundamental which are duplicated at twice the frequency. Thus it is clear that at least in some cases, true harmonic radiation is involved; the source region emits frequencies f and 2f simultaneously.
Evidence of Type II and Moving Type IV Solar Bursts Excited by a Common Shock Wave
Authors: Stewart R. T. , Sheridan K. V. , Kai K.
Published: July 2016

Travelling disturbances in the solar corona with velocities ~103 km/s manifest themselves at radio frequencies by two distinctive phenomena—the type II burst, the spectrum of which shows a slow frequency drift that corresponds to quasi-radial outward motion, and the moving type IV burst, for which positional observations show transverse motion directly. A close relation between the two phenomena has long been suspected, and each type has separately been ascribed to a shock wave disturbance. In this paper we summarize three events recorded by the Culgoora radioheliograph and spectograph (two in the course of publication and one unpublished) in each of which a type II and a moving type IV burst can be consistently attributed to the effects of a common shock wave.
Secondary Periodicities in Four Strong Pulsars at 80 MHz
Authors: Slee O. B. , Mulhall P. S.
Published: July 2016

During the interval May 1968 to March 1969 the 80 MHz radioheliograph at Culgoora has been used in a detailed study of the intensity variations in the pulsars CP 0834, 0950, 1133 and 1919. Some preliminary results for CP 1133 and 1919 have already been reported.
Problems in the Formation of Neutral Helium Lines in Early Type Stars
Authors: Simpson R. W.
Published: July 2016

The aim of this work is to investigate certain assumptions that have been made in calculating line profiles and equivalent widths of neutral helium lines in early type stars. The effect of electron scattering on the continuum flux is investigated and a curve of growth analysis carried out to study this effect. The theories involved in calculating the line absorption coefficient are also investigated.
The Molonglo Catalogue Survey
Authors: Davies I. M.
Published: July 2016

One of the basic tasks of the one-mile cross at the Molonglo Radio Observatory is the compilation of a catalogue of radio sources complete to a low flux density level. This level has been tentatively chosen as 0.2 f.u., which is well above the ultimate detection level which can be reached in selected areas of sky. Such a limitation is necessary if the catalogue is to be restricted to a manageable number of sources; a few tens of thousands, which will be achieved with the above limit, seems appropriate and useful at the present time.
On the Polarization of the 18 cm OH Emission
Authors: Bromley A. G.
Published: July 2016

The origin of the high degree of linear or circular polarization frequently observed in the 18 cm radiation of hydroxyl molecules has proved to be a formidable theoretical problem for which no adequate solution appears to exist at present. It is usually supposed that the radiation arises from some form of maser action and so it is possible that the polarization may arise from an interaction of radiation with the various frequencies and polarizations, through the coupling agency of the populations of the energy levels of the molecule.
Synchronization of Distant Clocks by Television Pulse Comparisons
Authors: Miller M. J.
Published: July 2016

The problem of synchronizing clocks at a distance has been solved both by the use of travelling clocks (e.g. caesium beam devices) and by radio transmission of time signals, for which active satellites are used to overcome inherent errors. A group of Czech workers recently developed a method of intra-continental clock comparison which makes use of the properties of domestic television signals. This has been verified under Australian conditions in experiments carried out between Mount Stromlo Observatory and the Division of Applied Physics of the National Standards Laboratory, CSIRO, Sydney, using signals from the Australian Broadcasting Commission transmitter ABWN 5A Wollongong.
Configuration and Evolution of Solar Magnetic Fields
Authors: Schatz D.
Published: July 2016

Observations were made on 1970 February 9 using the Culgoora magnetograph to study the configuration and evolution of magnetic fields in a solar active region with high time resolution. The region observed was located at N20 E25 at the beginning of the observations which commenced at February 8, 22h 59m U.T. and finished at February 9, 07h 24 m. The magnetic fields were observed in the light of Cal 6102.7Å. Over a wavelength range corresponding to an intensity from 1/8 to 1/2 of the way up from line centre to the continuum on the blue side of the Une there is no apparent change in the field configuration, and the observations were made at a wavelength corresponding to the mid-point of this range. Exposures were made approximately every two minutes, with occasional large time gaps for instrumental adjustments.
80 MHz Observations of the Movement of a Type IV Source out to 6 R®
Authors: Sheridan K. V.
Published: July 2016

A moving type IV radio source on 1970 March 21 was observed with the 80 MHz Culgoora radioheliograph to move out to a distance of p = 6 (where p = R/R®). Starting as a single source of complex shape it later developed strong circular polarization (> 90% R.H.) and separated into components which retained the same polarization. The source appeared soon after a prominence eruption (or flare spray) from which some of the ejected matter travelled in the same direction as, and with a velocity close to, that of the radio source.
On the Theoretical Treatment of Stellar Convection Zones
Authors: Unno Wasaburo
Published: July 2016

The theory of stellar convection zones has met three difficult problems. They are non-linearity, non-locality, and non-greyness of radiative transport. Non-linearity is inherent in turbulence. Non-locality is due to the nature of convection, that larger eddies are apt to be more unstable as indicated by the fourth-power dependence of the Rayleigh number on the vertical dimension. Inhomo-geneity and anisotropy of convection, penetration into stable layers, are the consequences. Non-grey radiative transfer through an eddy element is important in a convective atmosphere. In a preceding paper, the author has developed a theory which includes all these effects, using the representative eddy approximation. The emphasis in that paper was put rather in the non-locality and in the radiative non-greyness ; the treatment of non-linearity has been considered mainly in much earlier investigations. In the present note, we shall study how the representative eddy approximation is reconciled with the spectral theory of turbulence, and we shall determine the effective Reynolds and Péclet numbers, the coupling constants appearing in the eddy transport coefficients.
Velocity-Dependent Source Functions
Authors: Rees David E.
Published: July 2016

We consider the effect of a velocity gradient on the source function for a spectral line formed in an atmosphere in non local thermodynamic equilibrium, a problem examined previously by Kulander and Hummer and Rybicki. A numerical method is used which extends the Feautrier technique.
The Scattering of Line Radiation through States Perturbed in the Quasi—Static Limit
Authors: Argyros J. D.
Published: July 2016

An attempt is made to deduce the form taken by the distribution law for radiative scattering events performed by an atom whose energy—level structure is perturbed under conditions appropriate to the quasi-static limit.
A New Redistribution Function Applied to Radiative Transfer
Authors: Argyros J. D.
Published: July 2016

A redistribution function R(x, x′)dx dx′ is defined as the probability that a photon with frequency between x and x + dx will be absorbed by an elemental atmosphere which then emits another photon the frequency of which lies in the range from x′ to x′ + ax′. The frequencies x and x′ are measured from the central frequency νo of the spectral line in units of the Doppler width Δ The particular functional form taken by R(x, x′) in this discussion will be given by

where α represents the broadening of the spectral line in units of the Doppler width while the function H(o, z) is defined by

the Voigt function. The function defined by means of equation (1) is one of that class of redistribution functions which combines natural and Doppler broadening. Therefore, it should be expected that any results obtained using this particular redistribution function will exhibit certain features characteristic of this type of scattering.
Galactic Infrared Astronomy
Authors: Hyland A. R.
Published: July 2016

Until the last six years few infrared observations of astronomical objects (other than the Sun and planets) had been attempted. Those few were primarily concerned with obtaining bolometric corrections and effective temperatures, the variation of bolometric magnitudes of late-type variables, and the derivation of the laws of interstellar extinction.
Helium Abundance Determinations In Main Sequence B Stars
Authors: Simpson R. W.
Published: July 2016

The most recent helium abundance determinations in main sequence B stars are those of Hardrop and Scholtz, Kodaira and Scholtz, Norris, and Leckrone. Their results indicate that it is possible to assign a helium abundance which is characteristic of all B stars. Norris and Leckrone worked with a number of B stars ranging from B0 to B9, and both have assigned a characteristic helium abundance to the B stars. Norris derived a value, A = 0.088 ± 0.012, and Leckrone a value of A = 0.106 ± 0.01, where A is the abundance of helium relative to hydrogen by number.
Statistics of Double Star Measures
Authors: Luck J. M.
Published: July 2016

Some statistics from 368 plates of 111 double stars observed between July 1965 and January 1969 with the Yale-Columbia 26-inch refractor at Mount Stromlo Observatory, are presented. The results of plate measurements, and a description of the work, are to be published elsewhere.
Infinite Fine Structure Coupling in Radiative Transfer Problems
Authors: Mcnamara L. F.
Published: July 2016

The conditions for the equality of the line source functions associated with fine structure transitions in a multilevel atom have been examined by several authors. The equality or otherwise of the source functions depends largely on the value of the fine structure collision rate, equality occurring when this rate becomes infinitely large. The fact that the theoretical collision rates between fine structure levels of alkali atoms are so large suggests the possibility of simplifying complicated multilevel atom transfer problems by the consideration of the limit of an infinite fine structure collision rate.
A Fast Method for the Determination of Emergent Intensities in Radiative Transfer Theory
Authors: Cannon C. J.
Published: July 2016

One of the quantities usually required when solving the equation of radiative transfer is the intensity of radiation emerging from the surface of the medium under consideration. For multi-dimensional situations however, the methods presented to date have been numerical, and these first calculate the so-called source function Sv (r, Ω) as a function of position r, angle Ω and frequency v. This is generally the most difficult part of the exercise since an integro-difierential equation must be solved. The emergent intensity is then determined by solving a relatively simple first order differential equation by any of the well known numerical integration schemes. However, if the emergent intensity is required at a large number of angles, frequencies, and positions on the surface of the medium, and this is usually the case, the amount of computing needed may be considerable.
Depth Dependence of Physical Parameters Associated with Convection in the Solar Atmosphere
Authors: Waters B. E.
Published: July 2016

It has been often suggested that the solar granulation is essentially a turbulent convective phenomenon. It is then worthwhile to investigate steady state, finite-amplitude convection in the outer layers of the solar convection zone. On the basis that the convection zone is turbulent, we will define an eddy viscosity; and for the present we will consider only the first 300 km of the convection zone. This value is predicted by van der Borght using an asymptotic analysis of convection at high Rayleigh number—provided we assume the horizontal dimension of the cellular pattern to be ˜1000 km.
Aspects Of High Energy Astrophysics
Authors: Prescott J. R.
Published: July 2016

Observational astronomy extends, in terms of energy in the electromagnetic spectrum, from below 10-8eV to above 108eV. Studies of cosmic rays extend this range to the neighbourhood of 1019eV (about a Joule) and the aspects of high energy astrophysics discussed in the present paper are those concerned with cosmic rays of energy upwards of about 1015eV.
The Evolution of the Nuclei of Planetary Nebulae
Authors: Faulkner D. J.
Published: July 2016

In the past decade, planetary nebulae have assumed considerable importance in elucidating our understanding of the final stages of stellar evolution at low mass. This began with the work of Shklovsky, O’Dell and Seaton, who showed not only that the nuclei of these nebulae were among the hottest stellar objects, but also that they evolved on a track in the Hertzsprung-Russell diagram (the Harman-Seaton sequence) on a time scale very rapid by stellar evolutionary standards (~ 20,000 years).
A Model of the Solar Convection Zone
Authors: Waters B. E. , Van Der Borght R.
Published: July 2016

In a previous paper it was shown how one could improve upon the Böhm-Vitense model of the solar convection zone by the inclusion of four different length scales and by the determination of these length scales with the use of the quasi-Vitense model as developed by Unno. In this way the vertical wave number kz, associated with a characteristic eddy, can be determined by the integration of a second order differential equation. The integrations have to be started at a suitable depth and all model calculations depend critically on the assumed structure of the top layer.
A Model of the Evolution of the Flux Density and Polarization in Isolated Moving Type IV Bursts
Authors: Schmahl E. J.
Published: July 2016

In the first four years of operation with the 80 MHz heliograph at Culgoora, 24 events classified as moving type IV were observed. Their observed characteristics can be interpreted in terms of gyro-synchrotron radiation from mildly relativistic electrons. Many of these events have been presented at previous ASA meetings and 12 have been discussed in the literature in detail.
The Effect of Scattering on Solar Radio Sources at 80 MHz
Authors: Riddle A. C.
Published: July 2016

Scattering of radiation from solar radio sources by in homogeneities in the electron density structure of the corona can have marked effects on the observed time profile and the brightness distribution. These effects are appreciable for any localized source emitting a brief burst of radiation and are most pronounced when the radiation propagates close to the plasma level; it is such sources, illustrated here by those of type III bursts, that will be considered in this paper.
Solar Radio Observations of the Proton Event of 1971 January 24
Authors: Palmer I. D. , Smerd S. F. , Riddle A. C.
Published: July 2016

On 1971 January 24 a 3B flare at 18° N., 49° W. was associated with the acceleration of protons to relativistic energies; it was one of the rare events recorded by ground-level neutron monitors. Excellent radio coverage was obtained with single-frequency radiometers in the range 1000-9400 MHz, and at Culgoora with the 8-8000 MHz spectrograph and the 80 MHz radioheliograph. At the Earth relativistic protons and electrons arrived very promptly from the flare, whose site was near the foot of the nominal interplanetary field line which connects to the Earth.
CD-42° 14462—A Rotating White Dwarf (?)
Authors: Wegner G.
Published: July 2016

Recently E. M. Burbidge and P. A. Strittmatter1 have found that the DB-like star G61-29 has broad He emission lines suggesting a rapid rotation. The purpose of this paper is to suggest a further white dwarf candidate for rapid rotation.
Long Coherence Intercontinental Interferometry
Authors: Gubbay J. S.
Published: July 2016

Compact radio sources have been observed over several years at 2.3 GHz by interferometers of the NASA-JPL Deep Space Network with trans- or inter-continental baselines to study the secular behaviour of fine structure appearing in these sources. A comparison of the variation in flux density of components of diameter < 0.001 arcsec with the corresponding variation in total flux density of the source at the same frequency indicated that variations could be wholly ascribed to components of this order of magnitude.
Preliminary Results Obtained with an Aperture Synthesis Telescope at 30 MHz
Authors: Finlay E. A. , Jones B. B.
Published: July 2016

A 30 MHz radio telescope has recently been completed at Fleurs, N.S.W. There has been a need for a high resolution sky survey to be carried out in the Southern Hemisphere at a frequency intermediate between 19.7 MHz (Shain et al.) and 85.7 MHz (Mills et al). One particular reason lies in the fact that some HII regions which are seen in absorption against the galactic background at 19.7 MHz and in emission at 85.7 MHz may match the background temperature at 30 MHz. If the temperature of such a region has been found by other means, the 30 MHz temperature of the portion of the Galaxy beyond it is determined irrespective of conditions nearer the observer, since the two temperatures must be equal.
A Search for Cosmic Rays Streaming Out of the Galaxy
Authors: Fenton A. G. , Fenton K. B.
Published: July 2016

Evidence has been mounting for some years that cosmic rays have a dwell time in the disk of the Galaxy of 106-107 years. This evidence comes mainly from the study of the chemical composition of the cosmic rays, for if the particles were stored in the Galaxy for a longer time the heavy nuclei would suffer more collisions with interstellar matter and would be broken down into lighter nuclei or protons (see, for example, Shapiro).
Shock Waves and the Interpretation of the Chromospheric Calcium K-line
Authors: Cram L. E.
Published: July 2016

Dissipation of shock waves has often been proposed as the energy source required to sustain the outward temperature rise in the solar atmosphere. Theoretical models for the heating process have been developed by equating the mechanical energy input to the radiative energy loss at each height, but neither of these processes is well understood, and the lack of data means that the models are necessarily crude.
Masses of Old LMC Globular Clusters
Authors: Freeman K. C. , Munsuk Chun
Published: July 2016

Globular clusters in the Galaxy are all old objects, with ages of about 1010 years. The LMC is quite different: its globular clusters have ages anywhere between about 5 × 106 years and 1010 years. It is important to find out why globular clusters can form now in the LMC but not in the Galaxy; the galactic globulars play a major role in our picture of the early history of the Galaxy, and it is obviously desirable that we should understand the conditions under which these clusters can form.
Radio Observations of the Gum Nebula below 20 MHz
Authors: Ellis G. R. A.
Published: July 2016

Low frequency radio waves propagating in the interstellar medium are attenuated through absorption by thermal electrons, the optical depth being given by

where f is the radio frequency in MHz, the emission measure in cm-6 pc, and Te the electron temperature.
The Parkes 2700 MHz Survey—On-Line Reduction
Authors: Wall J. V.
Published: July 2016

Observations for the Parkes 2700 MHz catalogue are carried out in two stages: (i), a relatively fast finding survey, followed by (ii), accurate measurement (at 2700 MHz) of flux densities and positions of the sources on the survey scans. For the first six parts of the catalogue intervals of several weeks between the stages resulted from the necessity to reduce the (analogue) survey scans manually. This communication describes a computer program which records and reduces these scans, and which produces an on-line map and source listing for the survey region. Thus the measurements of the second stage may be carried out immediately after the survey; additional advantages provided by the technique are discussed later in the paper.
The Motions of Formaldehyde Clouds Near Sgr A
Authors: Whiteoak J. B.
Published: July 2016

It is well known that a molecular cloud complex with a radial velocity of 40 km s–1 is located in front of and near Sgr A, the non-thermal source at the centre of our galaxy. The motion of this cloud is generally interpreted as a contraction towards the centre. In terms of the general kinematics of our galaxy the existence of contraction is not firmly established – the main spiral features are either stationary with respect to the local standard of rest or expanding outwards from the centre (e.g., the 4 kpc expanding arm). However, as a result of a high-resolution study of the H2CO absorption arising in the molecular cloud, an alternative interpretation not involving contraction is suggested.
The Positions of Associated Type II and Type III Solar Radio Bursts
Authors: Duncan R. A.
Published: July 2016

Large solar radio outbursts at metre wavelengths often consist of a group of type III bursts followed a few minutes later by a type II burst; in both spectral types the intense burst radiation drifts towards lower frequencies with time (Figure 1).
A Flexible Fast-Photometry System
Authors: Rayner P. T. , Watson R. D.
Published: July 2016

A considerable amount of observational interest in short timescale phenomena has developed in optical astronomy in recent years. This interest has stemmed primarily from search efforts directed towards optical pulsars and the study of rapid fluctuations in cataclysmic variable and flare stars. Such studies have been made feasible by the development of the necessary photon pulse-counting technology required for rapid data sampling.
Krzeminsky’s Optical Candidate for Cen X-3
Authors: Wickramasinghe D. T. , Vidal N. V. , Bessell M. S.
Published: July 2016

Cen X-3 and Her X-1 are the only two X-ray binaries which are known to pulsate periodically (at 4.8s and 1.2s respectively) in the X-ray region. The latter was identified with a fourteenth magnitude light and spectrum variable HZ Her, which was subsequently found to exhibit 1.24 second optical pulsations during certain phases. The possibility that Cen X-3 may prove to be as interesting an object optically has resulted in a wide spread search for its optical counterpart.
Future Developments in Balloon-Borne X-Ray Astronomy
Authors: Thomas R. M. , Greenhill J. G.
Published: July 2016

While Uhuru’s contribution to X-ray astronomy in the energy range 1 – 20 keV (and more particularly 2 – 10 keV) has been most impressive, it remains true that satellite observations outside this energy range, and particularly at energies above 20 keV which are also accessible to balloon-borne instrumentation, have been somewhat disappointing. We cannot forsee any likely marked improvement in this situation for at least four years and we believe therefore, that balloon-borne payloads can continue to contribute significantly to the study of hard X-ray sources.
The X-Ray Pulsed Fraction of NP0532 and Interstellar Grains
Authors: Thomas R.M.
Published: July 2016

In this paper we report that the available data on the measured pulsed fraction of X-rays from the Crab Nebula between the energies 0.7 and 300 keV indicate that it is no longer necessary to postulate an intrinsic change in the pulsar spectral index near 30 keV. Furthermore the spectral flattening which is evident at low energies can be entirely attributed, within the precision of the available statistics to the destruction of time coherence of the pulse structure by the scattering action of interstellar dust grains.
Low Frequency Maps of the Galaxy
Authors: Cane H.V.
Published: July 2016

This paper is a preliminary report on the sky mapping being undertaken at the University of Tasmania using the Llanherne low frequency array. (Ellis 1972).

The observations are facilitated by the use of an on-line PDP-8 computer and the beam steering system described by Whitham (1975). In summary, a scanning system is used in which the computer is programmed to steer the telescope beam to a number of declinations with a time interval between settings such that a scan takes 5 minutes. Usually a scan of 12 declinations is chosen. Calibration levels obtained each hour and recorded on magnetic tape permit gain changes to be accounted for when the data is analysed from the tape.
An Observer’s-Eye View of the Anglo-Australian Telescope
Authors: Gascoigne S.C.B.
Published: July 2016

Commissioning of the Anglo-Australian Telescope (AAT) is now well along and regular scheduled observing will begin at the end of June. This paper is an account of the main features of the telescope as they will appear to observers, and is intended in particular as a guide to people who are formulating programmes. First however some remarks on the telescope design.
The Spectra of Sgr A and Sgr B2 between 1636 and 1640 MHz
Authors: Whiteoak J.B. , Gardner F.F.
Published: July 2016

The most prominent features in the spectra of Sgr A and Sgr B2 between 1636 and 1640 MHz are absorption lines corresponding to the 2π3/2, J = 3/2 ground state transitions of the isotropic species 18OH, which have rest frequencies of 1637.5 and 1639.4 MHz (Rogers and Barrett 1966). As a result of Doppler shifting, the lines of each transition are spread over a frequency range greater than 1.5 MHz. There are also present emission features which Zuckerman et al. (1971) have identified with the 110 -l11 transition of formic acid (HCOOH), which has a rest frequency of 1638.805 MHz. In view of some disagreement in the literature over the 16OH/18OH abundance ratio (Wilson and Barrett 1970; McGee et al. 1970), and of the baseline uncertainties in the spectra published in support of the HCOOH detection, we have obtained spectra of the two sources over the frequency range under discussion.
Progress on 21 cm Studies of the Southern Milky Way _
Authors: Kerr F.J.
Published: July 2016

In the first decade or so of 21 cm studies the galactic spiral structure problem was treated in a very straightforward manner. A simple velocity-distance transformation was used to derive the locations of the spiral arms from the radial velocities of the main features on the 21 cm profiles. Some well-known diagrams were obtained in this way.
A Search for HI Absorption in the Radio Spectra of the Quasi-Stellar Objects 4C 05.34 and PKS 0237-23
Authors: Peterson B.A. , Murray J.D. , Wright A.E.
Published: July 2016

The ratio of the mass density in visible galaxies to the upper limit for the HI mass density determined from the lack of continuous Ly-α absorption in QSO spectra is 3 × 104. Thus, if galaxies form by condensation from an intergalactic medium, the process must be extremely efficient. Although no absorption due to a continuous distribution of intergalactic HI has been detected, many QSOs have been discovered that have absorption lines in their spectra, which have redshifts very different from the emission lines, and may be produced in clouds of integalactic HI. As would be expected if this were the case, the proportion of QSOs with absorption lines in their spectra is greatest for those which have large emission line redshifts. Another possibility, especially for those absorption lines in redshift systems with Zabs nearly equal to Zem , is that the absorption lines are produced in clouds surrounding the QSO.
The AFCRL Catalogue: Some Southern Sources Studied
Authors: Longmore A. J. , Hyland A. R. , Allen D. A.
Published: July 2016

The strategic value of infrared sensing has prompted military development — mostly in the USA — of detectors for 8-30 μm far more sensitive than any commercially available. In 1970-72 the Air Force Cambridge Research Laboratories conducted a rocket-borne survey of the sky N. of about -35° dec at 4,11 and 20 μm. Although this survey was initially classified, a small number of preliminary versions of it were distributed to selected infrared astronomers based at U.S. institutions.
Observations of the 2π3/2, J = 7/2 State of OH
Authors: Balister M. , Gardner F. F. , Knowles S. H. , Whiteoak J. B.
Published: July 2016

The 6 GHz transitions of the 2π3/2, J = 5/2 excited state of OH are present in emission in the direction of several OH-emission regions (Rickard et al. 1975; Knowles et al. 1976), and in absorption in compact thermal sources (Gardner and Whiteoak 1975). This has suggested that transitions in the next highest state near 13 GHz (J = 7/2) might also be widely observable. A single detection has already been reported in W3OH by Turner et al. (1970). In this paper we report the observation of narrow-band emission in several other sources.
A Possible Configuration for the Australian Synthesis Telescope
Authors: Manchester R. N.
Published: July 2016

The proposal made to ASTEC for an Australian systhesis telescope (AST) is for a high-sensitivity, high-resolution synthesis array to be located at the Australian National Radio Astronomy Observatory, Parkes, and used in conjunction with the existing 64-m antenna at that site as a national facility (Wellington 1976). During the past 18 months a design study group consisting of representatives from the Australian National University, University of Sydney, University of Tasmania and CSIRO has been investigating the design of such an array. This paper reports on one aspect of this design, the array configuration.
Millimetre Wavelength performance of the new 16.7m surface of the Parkes Radio Telescope
Authors: Yabsley D. E.
Published: July 2016

A new surface installed recently over the central 16.7-m-diameter zone of the 64-m radio telescope at Parkes has extended the operating range of this instrument to millimetre wavelengths.