bluuebunny/crossref_metadata_2025 huggingface dataset:
58. Results of observations of the scattering of radio waves by the electronic inhomogeneities of the solar corona
Authors: Vitkevitch V. V.
Published: July 2016

A new method for the investigation of the solar corona, suggested by us (Vitkevitch, 1951) [1], consists of observing the radio source identified with the Crab nebula (NGC 1952; α = 05h 31m 40s, δ = 22° 10′) when it is covered by the solar corona. This occurs every year on 14–15 June.
70. Some properties of solar radio-transients on fast 200 Mc./s. records
Authors: De Jager C. , Van 'T Veer F.
Published: July 2016

Some 6 km. of high-speed (Brush) records of the solar radio radiation at 200 Mc./s. made at Cornell University by Ch. L. Seeger in 1949 and 1950 have been kindly put at our disposal. They were made with a paper speed of 0·5 cm./sec., sometimes with 2·5 cm./sec. The response time of the recording pen was 0s·02. Some records have been made simultaneously at 205 Mc./s. and at 200 Mc./s. This paper gives some results of a discussion of these records. The properties that were studied are: the clustering tendencies among the radio-pips, their band-widths, the echo-phenomena and the duration of the pips.
72. Some problems of meteor astronomy: Introductory Lecture
Authors: Whipple F. L.
Published: July 2016

We are now in an era of remarkable progress in the study of meteors. The electronic techniques developed at Jodrell Bank by Lovell, Clegg and others, and now by Davies, have culminated in giving us the power to observe the equivalent of 8th or 9th magnitude meteors for velocities, radiants and orbits. And certainly the limit has not yet been reached. The Harvard Super-Schmidt meteor cameras represent nearly the limit of current photographic-optical techniques; they approach close to the visual limit for very slow meteors, and with great precision, to 0·1 % in velocity and radiant.
73. Orbits of sporadic meteors
Authors: Davies J. G.
Published: July 2016

A survey of sporadic meteor orbits has been made using a spaced receiver technique. The apparatus consists of three receivers spaced on the ground by about 4 km. The received signals are brought together by radio links and displayed on a single film. In this way both diffraction pattern and the time delay between the diffraction patterns received at the different stations can be measured. From this the velocity and the direction of motion of the meteor can be calculated. The range of the echo and the local sidereal time are also recorded on the film.
75. Jupiter as a radio source
Authors: Burke B. F. , Franklin K. L.
Published: July 2016

Records obtained at a declination of about + 22° during the first quarter of 1955 with the 22·2 Mc./s. Mills Cross of the Carnegie Institution of Washington occasionally exhibited an interference-like event which was apparently a function of sidereal time. A plot of the right ascensions of beginning and end of each event (duration roughly fifteen minutes) against the date of occurrence revealed a smooth change of Right Ascension corresponding, initially, to a westward motion (Fig. 1). This pre-cluded correlation of the event with passage through the pencil beam of fixed objects like the galactic cluster NGC2420 and the planetary nebula NGC2392 which otherwise would have been candidates. The retrograde motion suggested a planet, and a canvass of the solar system uncovered only Jupiter and Uranus as possibilities. Of these, Jupiter exhibited the same position and the same change of position as did the event recorded, while Uranus was well out of the pencil beam much of the time. It was therefore concluded that the source of the radio emission was associated with Jupiter.
Observations of venus at 8.6-mm wavelength
Authors: Gibson J. E. , McEwan R. J.
Published: July 2016

Mayer, McCullough, and Sloanaker [1] and Drake and Ewen [2] have measured centimeter wavelength radiation from several of the planets; the former at 3.15 and 9.4 cm, the latter at a wide bandwidth centered near 3.75 cm. The first measurements were the observations of Venus by Mayer et al., made near inferior conjunction in late spring 1956. These were obtained with a sufficiently favorable signal-to-noise ratio to permit direct recognition of Venus in individual diurnal-rate scans, and a brightness temperature of 560 ± 73°K (mean error) was deduced for the planet at inferior conjunction, i.e. for the dark side of Venus.
Concluding lecture
Authors: Lovell A. C. B.
Published: July 2016

The preceding papers have demonstrated the remarkable development of the radio-astronomical investigations of the solar system during the last few years. The subject of meteors has been intentionally excluded, since this is now far too extensive to be included in a symposium of this kind. The radio echo, or radar, techniques have now been extended to reach the moon, and a further extension to the nearer planets can be anticipated soon. In the meantime, the study of the thermal and nonthermal radio emissions from the planets is developing rapidly, and important new results have been presented here. It will be convenient first of all to consider the implications of the new work on the radio echo investigations of the moon.
Les sources d'emissions radioelectriques du soleil
Authors: Denisse J. F.
Published: July 2016

Si les émissions radioélectriques du soleil sont dépourvues de la richesse d'informations apportée par les spectres optiques, elles se révèlent, par contre, particulièrement bien adaptées à l'étude d'une très grande variété de perturbations solaires, dont bien souvent les observations optiques n'avaient même pas permis de soupçonner l'existence, et ceci pour plusieurs raisons:

1. Ces émissions, souvent transitoires, intéressent particulièrement la couronne, ou la haute chromosphère, où les observations optiques sont discontinues et difficiles en raison de l'éblouissement par le disque photosphérique qui n'existe pas en radio.

2. Certaines ne sont pas d'origine thermique: le plasma coronal possède diverses possibilités de rayonnement (oscillations de plasma, rayonnement synchrotron ou Čerenkov) plus aisément ou seulement perceptible dans le domaine radioélectrique.

Les sources solaires d'émissions radioélectriques sont multiples et se distinguent essentiellement par leur stabilité plus ou moins grande et la nature de leur rayonnement; pour le moment on ne possède pas beaucoup d'indications sur leurs dimensions, encore moins sur leur structure.
A model of the chromosphere from radio and optical data
Authors: Athay R. G.
Published: July 2016

During the past few years various chromospheric models based on optical and ratio data have appeared in the literature. They exhibit an overwhelming tendency to recognize the chromosphere as a heterogeneous medium departing markedly from spherical symmetry. Beyond this general trend, however, their similarity all but vanishes. Perhaps the reason for this dissimilarity lies in the complexity of nonspherically symmetric models. The simpler ones, based on the assumption of spherical symmetry, however, show an equal diversity. It seems, therefore, that the diversity must be attributed to a lack of basic understanding of chromospheric phenomena.
La composante lentement variable du rayonnement solaire sur 169 Mc/s
Authors: Boischot A. , Simon P.
Published: July 2016

L'observation quotidienne du soleil à l'aide de l'interférometre à 32 antennes de Nançay [1] se poursuit sans interruption depuis le mois de Juin 1956. Bien que la période de maximum d'activité solaire dans laquelle nous nous trouvons ne soit pas très favorable à l'étude des propriétés du soleil calme, nous avons déjà obtenu un certain nombre d'enregistrements (3 ou 4 par mois en moyenne) absolument dépourvus des fluctuations toujours présentes dans le cas d'une émission non thermique liée à un centre d'activité, et de sursauts brefs de type I caractéristiques des orages de bruit.
Frequency drift and fine structure of 200-Mc/s solar bursts
Authors: Elgarøy Ø.
Published: July 2016

In 1957 high-speed records were obtained at a frequency of 200 Mc/s during solar radio noise storms at the Solar Observatory at Harestua. For the registrations a receiver of bandwidth 0.3 Mc/s and time constant 0.01 seconds was used in connection with a Brush recorder. Most records were secured at a paper speed of 25 mm/second.
The instantaneous position and diameter of short duration bursts of solar radio emission
Authors: Högbom J. A.
Published: July 2016

It is known that the regions responsible for solar noise storms are associated with visible sunspot groups and that the diameter of such radio sources is not less than 7 minutes of arc at a wavelength of 3.7 m. Little, however, is known of the size and location of the individual short-lived bursts (duration ~1 second). Two interferometric systems have been set up at 3.7 m to measure these quantities, and some preliminary results have been obtained:

(a) The diameters of single bursts. To measure the diameters of individual bursts an interferometer of spacing 270λ was connected to three receivers. Receivers 2 and 3 gave records corresponding to total power interferometers in antiphase, while receiver 1 was arranged as a phase-switching interferometer in quadrature with the other two. From the relative sizes of an individual burst on the three records it is possible to determine the burst intensity, its angular size and position in one coordinate. Measurements carried out during a noise storm on 1958 March 21 gave an angular diameter of 6 ± 1 minutes of arc for about 25 individual bursts.

(b) The location of single bursts in two dimensions. In order to determine the instantaneous position of individual bursts, two phase-switching interferometers of spacing 135λ were aligned in E-W and N-S directions. A third aerial was used with a total power receiver to measure the burst intensity. Preliminary results indicate that the positions of the individual bursts during a noise storm show a scatter of less than 3 minutes of arc.
New data on the solar supercorona
Authors: Vitkevich V. V.
Published: July 2016

1. This paper reports on the results of the investigation of the outermost regions of the solar corona (which for brevity I shall call the supercorona) that have been obtained during recent years.

Seven years ago, in 1951, a new method of observation was published in Doklady of the Academy of Sciences of the U.S.S.R. The idea of the method, which at the present time is well known, is that the radio emission of the Crab nebula is received at the time when the source is covered by the solar corona. This original eclipse takes place yearly in the middle of June.

By receiving the radio waves that pass through the solar corona regions, we can estimate the effects of attenuation, scattering and refraction and reach some conclusions about the structure of the supercorona.
Polarization of 10-cm radiation of the Crab nebula
Authors: Kuz'min A. D. , Udal'tsov V. A.
Published: July 2016

In October and November 1957 at the Physical Institute of the Academy of Sciences of the U.S.S.R. a search was conducted to detect the plane polarization of the radiation from the Crab nebula at 9.6-cm wavelength [1].
The accurate positions of 17 intense radio sources
Authors: Elsmore B.
Published: July 2016

Observations of 17 intense sources were made at a 1.9-meter wavelength with the Cambridge four-aerial interferometer [1] to provide information that may assist in their identification with optical objects, and as a check on the positions of a few of the sources of the recently completed third Cambridge survey [2].
Radio emission from the direction of the supergalaxy
Authors: Baldwin J. E. , Shakeshaft J. R.
Published: July 2016

Kraus and Ko [1] and Hanbury Brown and Hazard [2] have suggested that the band of radio emission running roughly perpendicular to the galactic plane at about 12h right ascension, represents the integrated emission from the concentration of bright galaxies lying along a great circle that crosses the galactic plane at longitudes l = 105 degrees and 285 degrees. This paper puts forward certain difficulties in this interpretation. These galaxies and our own are believed by de Vaucouleurs [3, 4] to be members of a “cluster of clusters,” which he terms the local supergalaxy, after Shapley.
An attempt to detect the 327-Mc/s line of galactic deuterium
Authors: Adgie R. L.
Published: July 2016

The previous unsuccessful attempts to detect the 327-Mc/s line of galactic deuterium [1, 2] were limited in sensitivity either by the size of aerial or by the inability to use long integration times with a large fixed aerial. The new observations reported here were made with the 250-foot radio telescope at Jodrell Bank, which can continuously follow a source of radiation; moreover, the effective integration time was improved by using a multi-channel receiver instead of a swept-frequency one.
Substructure within galactic spiral arms as derived from studies at 21 cm
Authors: Davies R. D.
Published: July 2016

Detailed structure within the spiral arms of our Galaxy is suggested by hydrogen-line spectra taken with high resolution in frequency [1]. The spectra show much detail in each maximum (spiral arm). It is not clear, however, if this frequency structure refers to fine structure in depth or in velocity dispersion or in both. Fine structure in position and depth has been inferred from 21-cm drift curves taken across the nearby spiral arms. The results of three investigations will be discussed. Two have been published in some detail [2, 3] and will only be summarized here.
Absorption of 19.7-Mc/s radiation in HII regions
Authors: Shain C. A.
Published: July 2016

The main program of the Sydney 19.7-Mc/s cross is devoted to the observation of the brightness distribution in a strip, extending some 10 degrees on either side of the galactic equator, the particular interest being the detection of absorption in HII regions. This program is well advanced, but since observing time is limited by ionospheric absorption and interference, records are not yet available for a number of galactic crossings. The detailed analysis of the observations has just begun, and will take some time. In the meantime a rough analysis of the data has been made in order to get a general picture of what might be expected, and this paper gives an outline of the results. The application of various instrumental corrections and the detailed analysis of ionospheric effects may subsequently necessitate some changes in the numbers involved in the calculations, but it is expected that the general conclusions will still hold.
On increase of the sensitivity and directivity of radio interferometers
Authors: Sanamian V. A. , Tovmasian H. M.
Published: July 2016

To discover the possibly large number of weak discrete radio sources and to determine their positions accurately is a very important and, at the same time, a difficult task. Radio telescopes with a large resolving power and a high-sensitivity receiver are necessary for this purpose.
Optical identification of southern radio sources
Authors: Basinski Jane , Bok B. J. , Gottlieb K.
Published: July 2016

The identification of discrete radio sources with optically observed celestial objects continues to be one of the most difficult and challenging tasks for the optical astronomer. Baade and Minkowski [1, 2] have done admirable work on the subject for the northern hemisphere and for the sections of the southern hemisphere accessible from the latitudes of Mount Wilson and Palomar Observatories. The zone south of declination −40 degrees, however, has not been studied to any great extent. As a part of our collaborative program of research with the C.S.I.R.O. Radiophysics Laboratory in Sydney, several members of the Mount Stromlo Observatory staff have initiated studies for the identification of sources with declinations south of −40 degrees.
Concluding lecture
Authors: Minkowski R.
Published: July 2016

The lively and extended discussions in this session have given to some extent an unduly pessimistic picture of the present state of the investigation of faint radio sources. It seems necessary to emphasize the fact that progress has been made, even if relatively few results are definitive and few problems have been solved.
Radio noise measurements on the passage of solar particles through the corona
Authors: Hartz T. R.
Published: July 2016

The swept-frequency receiver is one of the most powerful tools for studying the processes that go on in the sun's atmosphere. However, the instrumentation becomes fairly elaborate if a large frequency range is to be covered by such an apparatus. Consequently, only a few such receivers have been built, and those that are in operation are somewhat limited in their frequency coverage. It then seems worth while to examine the data from existing fixed-frequency receiving stations in order to determine the extent to which they can supplement or approximate the results of the swept-frequency apparatus. Many solar observations at fixed frequencies have been made and are still being made by numerous observers. These data contain much meaningful information if they can be interpreted successfully.
Radio astronomy and the origin of cosmic rays
Authors: Ginzburg V. L.
Published: July 2016

A paper [1] sent to the Manchester Symposium on Radio Astronomy in 1955 described the views developed earlier [2] concerning a magnetobremsstrahlung (synchrotron) origin of nonthermal cosmic radio emission. Unfortunately, for unknown reasons, it was not included in the Symposium volume [3]. At the same time the paper by Unsöld was published [3] (see also [4]), in which the nonthermal galactic radio emission is connected with radiation of a great number of cold dwarfs (radio stars). At the same time, Unsöld criticizes the theory of cosmic-ray origin, according to which the main sources of these rays are envelopes of supernovae and, perhaps, novae [2, 5, 6, 7, 8]. Therefore, we begin with some critical remarks.
Observations on microthermal fluctuations
Authors: Lynds C. R.
Published: July 2016

The concern has been expressed many times by Dr. Bowen and others that a significant portion of the seeing deterioration may occur in levels of the atmosphere very near the ground, within a few tenths of meters of the ground. When I refer to the quality of seeing I am refering to the image size one observes in a telescope of very large aperture and I will assume that this is equivalent to image motion as observed in telescopes of very small aperture. I will not attempt a further justification for this concern; however this is the basis for the studies we are just beginning at Kitt Peak, where we will attempt to quantitatively show whether or not there is need for concern about the very low levels of the atmosphere. So we begin with the thesis that much of the poor seeing observed at a site, the enlargement of photographic or visual images as observed through a large telescope, is due to refractive inhomogeneities in the lower levels of the atmosphere, within less than 100 m above the telescope. We presume that these inhomogeneities are of local origin and that their distribution and motion is determined primarily by site topography, wind direction and velocity. The few experiments we have made thus far at Kitt Peak have been designed to ascertain quantitatively the importance of these factors. Our approach has been to make observations of the large-aperture seeing with simultaneous observations of the thermal structure of the air accessible to us immediately above the telescope.
Studies of NGC 6067 and IC 2944
Authors: Thackeray A. D.
Published: July 2016

NGC 6067 is a very rich cluster free of nebulosity in the Norma Cloud, whose colour-magnitude array has been published by Thackeray, Wesselink, and Harding (1962). The choice of stars for measurement was highly restricted to a square approximately 10′ × 10′ of arc near the centre, so that above B = 13·0 only 10% are expected to be field stars, and between B = 15·0 and 16·0 some 20–30%.
The Me variables and galactic structure
Authors: Feast M. W.
Published: July 2016

Recently a program of radial velocity determinations for 114 southern long-period variables has been completed. Full details of these results and an analysis of them are being published elsewhere (Feast 1963). Below are summarized some of the results which seem of particular interest for problems of galactic structure.
The interpretation of recent 21-cm line data in terms of large-scale galactic structure
Authors: Westerhout G.
Published: July 2016

The detection of the 21-cm line 12 years ago opened up a vast new field of galactic research. But even though a large amount of data was assembled in these 12 years, our knowledge of the large-scale structure of our Galaxy still remains fairly limited. Let us summarize a few of the major facts which seem well established.
High-resolution studies of the galactic equator region
Authors: Kerr F. J.
Published: July 2016

A large program of observations is being undertaken with the 210-foot telescope at Parkes, to study the fine structure of the 21-cm line emission in the region of the galactic equator. With the aid of a multi-channel receiver, H-line profiles have been obtained every 6 min of arc (i.e. every half-beamwidth) along the equator from lII=300 to 60°, and also from bII = −3 to +3° along a number of constant-longitude lines. The bandwidth of each channel of the receiver is equivalent to 8 · 0 km/sec, with a spacing of 7 · 0 km/sec between the centres of adjacent channels. The data have been recorded on punched paper tape, and the main reduction is being carried out on the SILLIAC computer of the University of Sydney. A sample group of profiles, illustrating the great variability from point to point, has been published previously (Kerr 1962b).
The radio continuum emission from the Galaxy
Authors: Mills B. Y.
Published: July 2016

Study of the radio continuum emission from the Galaxy is of interest both from the viewpoint of the physics of the radiating processes and the light which these shed on physical conditions within the Galaxy, and also because the large-scale organization of the emitting regions gives information about the structure of the Galaxy as a whole. We are concerned here particularly with the latter aspect, that is, the question of galactic structure, and for this we need to know the distribution of the emitting regions throughout the Galactic System.
Comparison of stellar orbits in the Large Magellanic Cloud and in the Galaxy
Authors: Perek L.
Published: July 2016

The rotation curves of the LMC and the Galaxy differ markedly by the slope of the curve near the centre. Two causes may be responsible for this difference. Firstly, the mass of the Galaxy exceeds that of LMC by about one order of magnitude and the resulting orbital velocities at corresponding distances must be larger in the Galaxy than in the LMC. Secondly, the distribution of mass may be different in the two systems. Indeed, several investigations showed that the Galaxy is best represented by a model exhibiting a strong concentration of mass while the LMC is consistent with models of a very weak concentration, a homogeneous spheroid yielding a passable approximation.
Comparison of neutral hydrogen in NGC 55 and the LMC
Authors: Robinson B. J. , van Damme K. J.
Published: July 2016

Twenty-one-cm neutral hydrogen emission from NGC 55 has been measured with the 210-foot radio telescope at Parkes and a low-noise receiver (Robinson 1963). The beamwidth at 21 cm is 13′.5. NGC 55 has been classified by de Vaucouleurs as a SB(s)m system similar to the LMC, seen edgewise and with the luminous bar nearly along the line of sight (de Vaucouleurs 1961). The outer isophote published by de Vaucouleurs has dimensions of 45 by 9′, centred about 2′.5 to the south-following side of the bright “nucleus” in the centre of the bar.
Radio continuum emission from HII regions in the Magellanic Clouds
Authors: Mathewson D. S. , Healey J. R.
Published: July 2016

A considerable proportion of the radio emission at high frequencies from the Galaxy is of thermal origin. This thermal radiation appears to originate both in very extended regions and in discrete sources. It has always been difficult to compare the radio and optical data for these HII regions as galactic optical observations are hampered by heavy obscuration. However, the HII regions in the Magellanic Clouds are relatively free from obscuration, and spectrophotometry by Dickel, Aller, and Faulkner (this volume, paper 63) and Henize (1956) have provided very good measurements of Hβ and Hα flux densities and the relative intensities of the OII, OIII lines. Also the distance to the Clouds is fairly well known (about 55 kpc) so that the linear dimensions of the HII regions may be estimated with some degree of accuracy in contrast to the galactic emission nebulae.
Spectroscopic work in the Magellanic Clouds: NGC 330 in the SMC
Authors: Feast M. W.
Published: July 2016

This paper gives the results of a spectroscopic study of individual stars in the SMC cluster NGC 330. Before this, however, it may be useful to review briefly the spectroscopic evidence bearing on the questions of reddening and chemical composition in the Magellanic Clouds—matters about which there has not been entire agreement in the past.
New variables in the Large Magellanic Cloud
Authors: Dessy J. Landi
Published: July 2016

This work was performed in the same way as that corresponding to the Small Cloud (Landi Dessy 1959a, 1959b). Two hundred and seventy-seven new variables have been discovered, whose positions are shown by arrows in Figure 1. The pairs of plates used for blinking have from 80m to more than 1000d intervals.
On the accuracy attainable in the MK system
Authors: Jaschek C. , Jaschek M.
Published: July 2016

Recently we have finished at La Plata a catalogue containing all spectral classifications made in the MK system (1), prior to 1963·0. The original idea was to give a definite spectral classification for each object, but it was soon found out that this is impossible, since there is a relatively large number of stars for which the classifications given by different observers disagree. Therefore it was decided to include all published classifications, even knowing that in a number of cases the several classifications listed were taken from a single source. Some objects have therefore a long list of references, not necessarily independent. Incidentally these references permit a quick search for additional data on the star such as colour, polarization, rotation or line profile data. The catalogue lists a total of about 550 references. Whenever possible we have also listed, for each paper, the type of spectrograph and the dispersion used for the classification work. It is intended to keep the files up to date, issuing, if necessary, a second edition of the catalogue.
Spectral classification and three-colour photometry of A-type peculiar stars
Authors: Osawa K.
Published: July 2016

1. Since the pioneering works by Morgan (1) and later by Deutsch (2) for classifying A-type peculiar stars, many observers have discovered stars of this kind. A catalogue of Ap stars was compiled in 1959 by Bertaud (3). This catalogue is obviously very useful for astronomers in this field, but the type of peculiarity described in it is not homogeneous. The way of describing the spectral peculiarity differs somewhat with different observers, mainly due to the difference of dispersion of the spectrograph. The purpose of the observing programme of Ap stars reported in the present paper is to classify these Ap stars by an homogeneous system, and also to see relations between the spectra and the colours (B–V) and (U–B).
A luminosity discriminant in the infrared spectrum of late-type stars
Authors: Whitford A. E.
Published: July 2016

The sensitivity of the lines of the Na1 doubletλ8183–8195 (32P− 32D) to luminosity, previously noted by Sharpless (1) has been studied on spectra of MK standard stars ranging from K0III to M3III and from K2V to M6V. The prime focus spectrograph of the 120 inch telescope gave the same dispersion used by Sharpless, 200Å/mm. The objective was to test the suitability of the lines as an indicator of the contribution of dwarf stars to the total light of galaxies. Spinrad (2) and Deutsch (3) have noted that the sodium D lines are stronger in the spectrum of massive galaxies than would be expected if the dominant contribution to the total light came from giant stars. The advantages of the infrared sodium doublet are:

1. In a composite source, cool stars become a progressively more important contributor to the total radiation at longer wavelengths.
Ca II emission in a young K star
Authors: Thackeray A. D.
Published: July 2016

Ca11 emission (H and K) has been detected in Radcliffe spectra of the visual companion to the B5 star HD 113 703 which is regarded as a certain member of the Sco-Cen association. The star has been classified as K0V and its faintness has necessarily implied weakness of the spectra taken at 49 and 86Å/mm (at Hγ). But the Ca11 emission, which is clearly visible on four plates, is certainly quite abnormally strong for this type. Since the Sco-Cen association is regarded as about 20 million years old, the companion is presumably an exceptionally young K star. The observation thus supports the concept of such chromospheric activity being associated with youth.
Spectrophotometric measurements of objective-prism spectra
Authors: Schmidt-Kaler Th.
Published: July 2016

I should like to give you a very condensed progress report on some spectrophotometric measurements of objective-prism spectra made in collaboration with H. Leicher at Bonn. The procedure used is almost completely automatic. The measurements are made with the help of a semi-automatic fully digitized registering microphotometer constructed by Hög-Hamburg. The reductions are carried out with the aid of a number of interconnected programmes written for the computer IBM 7090, beginning with the output of the photometer in the form of punched cards and ending with the printing-out of the final two-dimensional classifications.
Two-dimensional classification systems for O-type stars
Authors: Hack M.
Published: July 2016

An observational programme of O and early B-type stars is being conducted at the Merate Observatory (1, 2) with the grating spectrograph. The dispersion is 35Å/mm and the spectral rangeλλ3300–4700. The purpose is to find criteria for a two-dimensional classification of O-type stars.
Photo-electric Hβ and uvby photometry
Authors: Crawford D. L.
Published: July 2016

Early in the 1950's Strömgren (1, 2, 3, 4, 5) introduced medium to narrow-band interference filter photometry at the McDonald Observatory. He used six interference filters to obtain two parameters of astrophysical interest. These parameters he calledlandc, for line and continuum hydrogen absorption. The first measured empirically the absorption line strength of Hβby means of a filter of half width 35Å centered on Hβand compared to the mean of two filters situated in the continuum near Hβ. The second index measured empirically the Balmer discontinuity by means of a filter situated below the Balmer discontinuity and two above it. He showed that these two indices could accurately predict the spectral type and luminosity of both B stars and A and F stars. He later derived (6) an indexmfrom the same filters. This index was a measure of the relative line blanketing near 4100Å compared to two filters above 4500Å. These three indices confirmed earlier work by many people, including Lindblad and Becker. References to this earlier work and to the systems discussed today can be found in Strömgren's article inBasic Astronomical Data(7).
The progress of multicolour photometry
Authors: Walraven Th.
Published: July 2016

After the introduction of photography as a tool in astronomy, the spectroscopists were the first to open a new field of exploration, i.e. the study of the physical nature of stars.

They gradually split up in different groups. The coudé spectroscopists studied spectra of high resolution and with much tedious work measured the equivalent width of each line and the shape of the line profiles. This work is restricted to the brightest stars.
The optics of interstellar grains
Authors: Greenberg J. M.
Published: July 2016

A considerable amount of interesting theoretical and observational work on the subject of interstellar grains has been done during the past few years. A few items are selected for detailed presentation.
General calibration problems
Authors: Petrie R. M.
Published: July 2016

During this symposium we have already heard papers which have dealt with the calibration of certain spectral parameters. In this session we turn to the matter of calibrating luminosity criteria in terms of absolute magnitude. This is a central problem in studies of our Galaxy and it finds in this topic its widest application. At the same time we remind ourselves that the determination of absolute magnitude is necessary in studies of stellar structure and stellar evolution since this information tells us about the radiation passing through the stellar interior and the stellar atmosphere and of the amount of energy generated by the star. The luminosity also allows us to calculate the size of a star and to estimate its surface gravity.
Spectrophotometric programmes for galactic research
Authors: Elvius T.
Published: July 2016

1.Spectrophotometric methodsfor determination of spectral type and luminosity have been used since long at the Uppsala and Stockholm Observatories.† They rely on densitometric evaluation of objective-prism spectrograms from astrographs and Schmidt telescopes. The handbook articles by Fehrenbach (2) and Strömgren (3) give the essentials of the methods as developed by Lindblad, Stenquist, öhman, Ramberg, and later by Westerlund.
Desiderata in connection by the calibration of the MK-system
Authors: Schmidt-Kaler Th.
Published: July 2016

This is only an informal remark about some difficulties I am worrying about.

I have tried to recalibrate the MK system in terms of intrinsic colour (B–V)0and absolute magnitudeMv. The procedures used have been described in a review article by Voigt (Mitt. Astr. Ges.1963, p. 25–35), and the results for stars of the luminosity classes Ia-O,I and II have been given also in Blaauw's article on the calibration of luminosity criteria in vol. III (Basic Astronomical Data, p. 401) ofStars and Stellar Systems.
Multicolour Photometry at Mount Stromlo Observatory
Authors: Westerlund B. E.
Published: July 2016

Current photometric programmes at Mount Stromlo Observatory of which accounts have been recently published, for instance, Graham's Hβphotometry (1), will not be considered here.
The HR diagram of NGC 1893
Authors: Hiltner W. A.
Published: July 2016

During the past few years Prof. Morgan and I have been reobserving the brighter members of a number of clusters. New classification spectrograms are obtained andUBVphotometry where ever needed. The work on the Hyades and NGC 6530 is now complete and has been submitted to theAstrophysical Journalfor publication. The work on NGC 1893, which I reported on very briefly, is one of that series.
A Search for Diffuse Interstellar Features in Stars with Circumstellar Dust Shells
Authors: Snow Theodore P. , Wallerstein George
Published: July 2016

We have searched for diffuse features at λ 4430, 5780 and 6613 in the spectra of 17 stars which show infra-red excesses or other grounds for believing that they have dusty envelopes. In no case could we identify diffuse bands that may be ascribed to the circumstellar envelope. We conclude that the grains in circumstellar envelopes are not identical with the grains in the general interstellar medium.
Diffuse Interstellar Features in the Spectra of Dust-Embedded Stars
Authors: Bromage G. E. , Nandy K.
Published: July 2016

Eleven diffuse interstellar features have been studied in the spectra of dust-embedded stars in Cyg OB2 (VI Cyg) (including a Wolf-Rayet star) and field stars in the same direction. The equivalent widths of the lines are all strongly correlated with each other and with EB – V, but there is virtually no correlation with D line strength for these stars. The wavelength positions and half-widths of the diffuse lines appear to be the same for all stars studied.
Broadband Structure in the Interstellar Extinction Curve
Authors: Hayes D. S. , Mavko G. E. , Radick R. R. , Rex K. H. , Greenberg J. M.
Published: July 2016

We have analysed observations of the interstellar extinction in the range 3400 Å–l 1000 Å. The observations have high photometric accuracy and wavelength resolution, and allow a detailed examination of broadband structure as well as the general shape of the wavelength dependence of the extinction curve. The broadband structure has a characteristic size of several hundred ångströms, and may be as important as the diffuse bands in indicating the physical nature of the grains.

We describe our preliminary theoretical interpretation of this broadband structure, and the new observation which it predicts.
A Study of the Interstellar Diffuse Absorption Features
Authors: Wu Chi-Chao
Published: July 2016

At a resolution of 0.17 Å, the profile of λλ 5780, 5797 were found to be asymmetric and steeper to the blue. The FWHM of λ 5780 and λ 5797 are respectively 2.7 Å and 1.1 Å. There is also a broad, shallow feature shortward of λ 5780. Equivalent widths of λλ 5780, 5797 were measured at a resolution of 0.26 Å, and they present a very tight correlation. Therefore, it is highly likely that these two diffuse lines have a common origin. The correlation between the equivalent width of λ 5780, EW(λ 5780), and E(B – V) is good for normal field stars. But there is a systematic weakening of λ 5780 in the spectra of Be stars, and the reverse is true for stars in the Scorpius-Ophiucus region. Excluding Be stars, a least square fit gives EW(λ 5780) = 0.75 E(B – V) Å mag.–1. From the profiles and structures of the diffuse features, and the correlations with various parameters of the interstellar medium, it is suggested that: (1) the diffuse band λ 4430 may be produced by the preionization of H– and, (2) λλ 5780, 5797 may be due to the pure electronic transitions of the impurity centers in solid grains.
Surface Polarimetry of the Milky Way
Authors: Wolstencroft Ramon D.
Published: July 2016

Two methods of determining the state of polarization of the integrated light from the Milky Way are discussed. In the symmetry method it is assumed that the polarized foreground zodiacal light possesses north/south symmetry relative to the ecliptic: an average polarized intensity of at least 10 S10(R) is derived for the Milky Way at l ≃ 90° and 270°, which is consistent with the result of Sparrow and Ney (1972) who obtained 18 S10 (R) at l = 35° and 210°. In the method of two epochs the above assumption is not needed but instead time variations of the zodiacal light are assumed to be insignificant: the results obtained by this method (in S10 (V) units), although compatible with the values found by the symmetry method, do however show that time variations may have influenced this result. Although the evidence for a definite polarization of the Milky Way is persuasive it cannot yet be considered conclusive.
Development of Photographic Techniques for Photometry and Polarimetry of Faint Stars in the R–IR Region
Authors: Treanor P. J.
Published: July 2016

Photometric and Polarization measures of fainter stars (m > 11) are still very few, especially in the red to infra-red region. In order to exploit large Schmidt cameras to remedy this shortage, improved methods of photographic calibration are needed. This note reviews some of the problems associated with photographic calibration of direct images, and presents a progress report on the development of the ring polarimeter.
Photon and Magnetic Alignment of Interstellar Dust Grains
Authors: King Leon W. , Harwit Martin O.
Published: July 2016

We have considered the cooperative effects of photon and magnetic alignment on plausible models for interstellar dust grains. Neither effect, either in cooperation or alone, appears able to produce the observed alignment.
Interstellar Reddening at High Galactic Latitudes
Authors: Philip A. G. Davis
Published: July 2016

Measures in the Strömgren four-color and Hβ systems provide an accurate way to determine color excesses of early-type stars. Fourteen areas at high galactic latitude have now been searched for faint A stars which are then measured photoelectrically to obtain the color excesses. Non-main sequence A stars, which are easily detected by means of the four-color photometry, are not included in the analysis. Within 40° of each pole, the reddening is essentially zero, Eb–y = 0.00 north of the galactic plane and Eb–y = 0.01 south of the plane.
Destruction of Dirty Ice Mantles by Sputtering
Authors: Aannestad P. A.
Published: July 2016

Dirty ice mantles are destroyed efficiently by sputtering of He atoms when clouds encounter shock velocities greater than 13–15 km s–1. Destruction due to grain-grain collisions is found to be about 10–3 times less efficient. Sputtering in the hot intercloud medium should make intercloud grains smaller than cloud grains.
Some Implications of the Distribution of Interstellar Molecules
Authors: Snyder Lewis E.
Published: July 2016

It is suggested that molecular observations of interstellar clouds can be used to determine the stage of cloud evolution. However, before observational data can reliably be used to investigate the evolutionary path leading from a tenuous cloud of gas and interstellar dust to a star cluster, mechanisms of molecular formation, excitation, and destruction must be taken into account. The evidence is growing that interstellar dust grains have an important role in molecular formation and destruction.
Formation Mechanism for Interstellar Molecules
Authors: Harteck Paul , Beaudoin Arthur , Reeves Robert
Published: July 2016

The gas phase production of molecules in dust clouds in interstellar space may occur largely as H2 formation on the interstellar grains, with relatively minor formation in the gas phase. The formation of more complex molecules, however, may be augmented by gas phase processes including (1) negative ions formed by radiative attachment of electrons, (2) direct radiative association of molecules and atoms, and (3) reaction of atoms and molecules with H3+ molecules.
Infrared Observations of Stars in the Association Cyg OB2
Authors: Voelcker K. , Elsässer H.
Published: July 2016

About 80 stars of the association Cyg OB2 have been observed in J, H, K and L. These measurements have been made in search for infrared circumstellar emission in this highly reddened association.
The Evolutionary Status of PSR 1718–19
Authors: Ergma Ene , Sarna Marek J.
Published: July 2016

Possible models for the matter source inside the eclipsing binary system PSR 1718–19, and for the evolution of this system are reviewed, including Zwitter's (1993) stripped main-sequence (MS) turnoff star model. Both the accretion induced collapse (AIC) scenario with a young neutron star, and the capture scenario with an old neutron star are discussed. Although Burderi & King (1994) claim that the size of the Roche lobe (∼0.5 R⊙) unambiguously rules out the AIC formation scenario, we show that in our evolutionary picture an AIC scenario will be possible.
The Local Low-Mass Binary Pulsar Population
Authors: Lorimer D.R.
Published: July 2016

Using a fully self-consistent approach to account for known survey selection effects, we constrain the number and scale height of low-mass binary pulsars (LMBPs) in the local solar neighbourhood. Our results show that the local surface density of LMBPs with luminosities above 2.5 mJy kpc2 is ∼20 kpc−2. Assuming that these are long-lived (≲1010 yr) objects, their local birth rate is at least 2 10−9 kpc−2 yr−1. Whilst this is in excellent agreement with the birth rate of their proposed progenitors, the low-mass X-ray binaries, there are several uncertainties involved which could significantly increase our derived birth rate, perhaps by an order of magnitude. Models in which the scale height of LMBPs above the galactic plane exceeds 500 pc are found to be most consistent with the data. The mean space velocity at birth required to produce scale heights of this order in 1010 yr is found to be ≳ 80 km s−1.
The Masses of the Neutron Stars in M15C
Authors: Deich W.T.S. , Kulkarni S.R.
Published: July 2016

Several years of timing the pulsar in the binary neutron star system M15C have yielded the masses of both stars: the total mass is MT = 2.7121(6) M⊙; the companion mass is mc = 1.36(4) M⊙; and the pulsar mass is mp = 1.35(4) M⊙. We argue that this system is not likely to have formed through accretion-induced collapse (AIC), and that the standard model also has problems in explaining the formation.
Optical Photometry of Black-Hole Candidates
Authors: Haswell C. A.
Published: July 2016

The orbital light curves of SXTs are discussed. In principle, the orbital inclination can be determined from the ellipsoidal variations, allowing a complete solution for the component masses. Complications in this analysis are described, and the evidence for superhumps in the light curves is reviewed. Constraints on the compact-object masses derived from superhumps are described.
ROSAT Observations of Globular Clusters in the Galaxy and in M31
Authors: Johnston Helen M. , Verbunt Frank , Hasinger Günther , Bunk Wolfram
Published: July 2016

X-ray sources in globular clusters fall into two categories: the “bright” sources, with LX ∼ 1036-1038 erg s−1, and the “dim” sources, with LX ≲ 1034.5 erg s−1. The bright sources are clearly associated with accreting neutron stars in binary systems. The nature of the dim sources, however, remains in doubt. We review recent observations of globular-cluster X-ray sources with the ROSAT satellite. ROSAT detected bright sources in M31 globular clusters and greatly increased the number of dim sources known in galactic globular clusters. We discuss what these new observations have taught us about the distribution and nature of such sources, their spectral properties, and their underlying luminosity function.
AM Herculis Binaries
Authors: Beuermann K.
Published: July 2016

AM Herculis binaries contain mass accreting magnetic white dwarfs which appear as bright X-ray sources in the ROSAT All Sky Survey. About 52 systems are presently known which allow detailed studies of the evolution of magnetic close binaries and of fundamental plasma-physical processes in the accretion region on the white dwarf.
Gamma-Ray Bursts: Observational Overview
Authors: Fishman Gerald J.
Published: July 2016

Gamma-ray bursts remain one of the greatest mysteries in astrophysics in spite of new and more detailed observations made with the BATSE experiment on the Compton Observatory. The new observation with the greatest impact has been the observed isotropic distribution of bursts along with a deficiency of the weak bursts which would be expected from a homogeneous burst distribution. This is not compatible with any known Galactic population of objects. Other recent important observations include an enormous variety of burst morphologies and gamma-ray burst photons extending to GeV energies. A time dilation effect has also been reported to be observed in gamma-ray bursts.