bluuebunny/crossref_metadata_2025 huggingface dataset:
Theory of interstellar molecules
Authors: Salpeter E. E.
Published: July 2016

Various estimates are described for the rate of formation of hydrogen molecules on the surface of interstellar grains in H 1 regions. The average abundance of molecular hydrogen relative to atomic hydrogen remains uncertain by a few orders of magnitude.

Possibilities are presented for the formation of OH molecules (and, more briefly, for other diatomic molecules), either on the surface of dust grains or by exchange reactions in the interstellar gas after cloud-cloud collisions. The rate for photodissociation of OH in H 1 regions is uncertain.

A brief discussion is given of various possible mechanisms for maser action in the OH molecule, such as optical pumping of microwave levels by UV radiation at the edge of an H 11 region. It appears that the narrow OH emission lines must originate in cool gas bordering an H 11 region.
Berkeley results on OH emission
Authors: Dieter N. H. , Weaver H. F. , Williams D. R. W.
Published: July 2016

This paper briefly summarizes studies of the position, polarization, and spectral variations of OH emission sources.
General characteristics of interstellar clouds and their interpretation
Authors: Kahn F. D.
Published: July 2016

This report is concerned with recent progress on various aspects of interstellar gas dynamics, including an investigation of the Orion Nebula, studies of H 11 regions and of ionization fronts, a statistical model of H 1 clouds and a re-appraisal of the heating and cooling processes in H 1 regions.

Dyson has worked out a new model for the Orion Nebula, in which it is supposed that dense pockets of non-ionized gas exist within the H 11 region. He makes predictions concerning the flow of ionized gas around these pockets, and about the possible presence of shock-waves nearby.

Mendis has extended Axford's classical description of ionization fronts to include the case in which a front advances into a region where the hydrogen is molecular, and finds that there are a number of consequent changes in the nature of the front. Hjellming has given a comprehensive account of the processes by which a thermal balance is achieved in an H 11 region, and has shown how the temperature in its various parts depends on the distance from the exciting star and on the stellar surface temperature. Mathews has integrated the equations of motion for a growing H 11 region, and has described how ionization fronts develop and when shocks will occur. Lasker has followed the motion further, and has given examples to show how older H 11 regions evolve.

By means of a simple model of H 1 clouds, Field and Saslaw have tried to estimate how long it would take to form a massive interstellar complex which would become gravitationally unstable. They find that the time required is relatively short. One must therefore assume that only a small fraction of an unstable cloud can condense into stars, or else the rate of star formation would be too rapid.

Finally an estimate is made of the rate at which early-type stars supply kinetic energy to the H 1 clouds, via the expansion of H 11 regions. One cannot, with the present data, decide definitely whether this process is important. A possible alternative would be the acceleration of gas clouds by supernova shells.
The energization of the interstellar medium by ionization-limited H 11 regions
Authors: Lasker Barry M.
Published: July 2016

The energy input into the interstellar medium from ionization-limited H 11 regions is estimated at 1·4 × 10-28erg cm-3sec-1, an order of magnitude lower than the anticipated dissipation.
The effect of magnetic fields on interstellar clouds
Authors: Pikel'ner S. B.
Published: July 2016

I should like to say something about the equilibrium of the gas in spiral arms and about the interaction of interstellar clouds. The polarization of the light of distant stars shows that there is a quasi-regular magnetic field inside the clouds, and the Faraday rotation indicates the same for the gas between the clouds.
Local structure and large-scale motions from young objects
Authors: Schmidt-Kaler Th.
Published: July 2016

Substitution of the value 3·2 for the ratioRof total visual extinction to reddening leads to a revision of the galactic rotation curve determined by Feast and Shuttleworth. The new results agree very well with the 21-cm rotation curves, particularly with those by Kwee, Muller and Westerhout and by Shane and Bieger-Smith. The corresponding local value for Oort's constant isA= + 15.2 km sec-1kpc-1.

With the exclusion of special regions like Orion, the ratioRappears to vary only little about an average of 3·2. This value gives a clearer spiral pattern than the strong variations ofRwithladvocated by Johnson; also it leads to better correlation of velocity with distance at the maxima of differential galactic rotation.
Comparison of the distribution and motion of atomic hydrogen in our own Galaxy and in other spiral systems
Authors: Burke B. F.
Published: July 2016

Our own stellar systemhas been studied in some detail by the Leiden and Sydney groups, whose maps of the large-scale hydrogen distribution are well-known; these are discussed by Lindblad in Paper 24 of this Symposium volume. The distances in our Galaxy are sufficiently small to reveal significant structure on the order of size of spiral arms, but the lack of a direct distance scale, with an indirect scale to be inferred from velocity models, is a serious handicap in reaching definite conclusions about the symmetry, number of spiral features, and inclination of spiral arms. In fact it is very difficult to decide whether the gas arms coincide with the spiral arms as defined by stars. By the study of external galaxies one can remove the scale uncertainty, but only at the cost of a serious lack of detailed information on the structure, because angular resolution is relatively poor, even with the largest existing telescopes. The largest, the 300-foot (91-m) transit telescope of the National Radio Astronomy Observatory at Green Bank, West Virginia, has a beamwidth of 10′ (arc) at 21 cm, which is larger than the angular dimensions of all but the closest external galaxies.
Motions of neutral hydrogen at high latitudes
Authors: Blaauw A. , Fejes I. , Tolbert C. R. , Hulsbosch A. N. M. , Raimond E.
Published: July 2016

Earlier investigations have shown that there is a preponderance of negative velocities in the hydrogen gas at high latitudes, and that in certain areas very little low-velocity gas occurs. In the region 100° <l< 250°, + 40° <b< + 85°, there appears to be a disturbance, with velocities between - 30 and - 80 km/sec. This ‘streaming’ involves about 3000 (r/100)2solar masses (rin pc). In the same region there is a low surface density at low velocities (|V| < 30 km/sec). About 40% of the gas in the disturbance is in the form of separate concentrations superimposed on a relatively smooth background. The number of these concentrations as a function of velocity remains constant from - 30 to - 60 km/sec but drops rapidly at higher negative velocities. The velocity dispersion in the concentrations varies little about 6·2 km/sec. Concentrations at positive velocities are much less abundant.
Possible interpretations of the high-velocity gas
Authors: Oort J. H.
Published: July 2016

After a brief summary of observational information on gas with high and intermediate velocities, the objections against several possible origins for these phenomena are reviewed. The best hypothesis appears to be an intergalactic origin, near the Local Group. The intergalactic density required if the observed high-velocity flow is a continuing phenomenon is estimated at 10 to 100 × 10-29g cm-3, depending on thez-distance of the intergalactic matter at the time of its deceleration by galactic gas, and on the importance of cosmic rays in this deceleration. The effects of the observed inflow of gas on galactic dynamics may be of great significance.
Infalling metagalactic gas clouds and galactic cosmic rays
Authors: Puppi G. , Setti G. , Woltjer L.
Published: July 2016

We wish to suggest (see also Puppi, Setti and Woltjer 1966) that the interaction between matter falling into the Galaxy and cosmic rays may be important both in slowing down the infalling material and in contributing to the acceleration of cosmic rays.
High-velocity cloud collisions
Authors: Savedoff M. P. , Hovenier J. W. , van Leer B.
Published: July 2016

At the suggestion of Professor Oort, we have investigated a model for the collision of a high-velocity cloud with galactic gas. Oort considers a snow plow model, for the incoming cloud has a unique density and velocity, etc., and conservation of momentum is used as for such a solid body. The three-dimensional hydro-dynamic problem is quite expensive to carry out both in computer and in human time. We consider alternatively a shock-tube model which permits easy comparison with observations.
Places of formation of young and moderately young stars
Authors: Strömgren Bengt
Published: July 2016

Narrow-band photoelectric photometry can furnish classification indices allowing accurate determination of stellar ages. From these ages, together with well-determined space motions, the places of formation of stars, and their relationship to the spiral structure of the Galaxy, may be determined. This procedure has been successfully followed for 52 B8–B9 stars within 200 pc from the Sun. It turns out that seven of these have originated in the Perseus Arm, with local peculiar velocities of about 22 km/sec.

A simple model is developed describing places of star formation in the Perseus Arm and velocities at formation. The distribution of space velocities and of ages for stars formed according to this model appears to be in agreement with observation.
Structure in the radiation of the galactic disk
Authors: Davies R. D.
Published: July 2016

Observations at various frequencies between 136 and 1400 MHz indicate a considerable amount of structure in the galactic disk. This result appears consistent both with measured polarization percentages and with considerations of the strength of the galactic magnetic field.
Dual-beam observations at 1417 MHz of the region of the North Polar Spur
Authors: Davis M. M. , Merkelijn Jeannette K.
Published: July 2016

This is a preliminary report of a survey carried out with a dual-feed system, which measures the intensitygradientalong a path in the sky swept by the motion of the telescope. The accuracy reached is 0·04 °K of antenna temperature per 2° beam separation.
Observing the galactic magnetic field
Authors: van de Hulst H. C.
Published: July 2016

Various methods of observing the galactic magnetic field are reviewed, and their results summarized. There is fair agreement about the direction of the magnetic field in the solar neighbourhood:l= 50° to 80°; the strength of the field in the disk is of the order of 10-5gauss.
Magnetic-field strengths from optical polarization data
Authors: Greenberg J. M.
Published: July 2016

Van de Hulst (Paper 64, Table 1) has marked optical polarization as a questionable or marginal source of information concerning magnetic field strengths. Rather than arguing about this–I should rate this method asq+-, or quarrelling about the term ‘model-sensitive results’, I wish to stress the historical point that as recently as two years ago there were still some who questioned that optical polarization was definitely due to magnetically-oriented interstellar particles.
Recent advances in X-ray astronomy
Authors: Rossi B. B.
Published: July 2016

In a review written in December 1965, the author of this report has summarized the state of observational X-ray astronomy at that time. Further data that have become available since then have produced important advances in several directions. New sources have been discovered, some of which have been tentatively identified with known galactic or extra-galactic objects. Evidence has been presented for variability of the X-ray flux received from at least one of the sources. New spectral information has been obtained. New observations of the strong X-ray source in Scorpius, Sco X-1, have greatly reduced the previous upper limit for its angular size and have provided a much more accurate determination of its celestial coordinates. This determination has led to the identification of Sco X-1 with a faint visible object whose peculiar properties had, until then, escaped the attention of astronomers.
Absolute intensity calibration methods in the vacuum UV region
Authors: Boldt G.
Published: July 2016

As a summary of the principal results presented at the ESRO symposium on Calibration Methods in the Vacuum Ultra Violet (Munich, 1968) a description is given of three different absolute intensity calibration methods. These are the branching ratio method, the synchrotron radiation method and the black-body radiation method, and they define the present state of the art.
An investigation of the properties of vacuum-ultraviolet radiation detectors
Authors: Tiyt Valdur M.
Published: July 2016

At the Institute of Physics and Astronomy of the Academy of Sciences of the Estonian S.S.R. there is a laboratory for the research on the properties of detectors for vacuum ultraviolet radiation. The laboratory has also the necessary measuring equipment, including a beam double vacuum monochromator for the wavelengths 1000–2700 Å with a balancing-out system of registration attached to it. The last-named device automatically eliminates effects on the results of measurement caused by the distribution of energy in the spectrum of the light source as well as by absorption in the apparatus.

Earlier the absolute efficiency of detectors was determined by means of a thermocouple but at present it is calculated from the data obtained from the photoionisation cross sections of gases.

The present report throws light on some results of the investigation of the properties of radiation detectors under different operating conditions.
Ultraviolet interstellar extinction from a comparison of ∊ Persei and ζ Persei
Authors: Stecher Theodore P.
Published: July 2016

Hall's and Stebbins and Whitford's extinction pair has been used to determine interstellar extinction in the ultraviolet. The extinction shows a feature suggestive of graphite. Previous observations of Stecher (1965) are confirmed. The results are presented in the figures.
The effective temperatures of the O stars
Authors: Morton Donald C.
Published: July 2016

Effective temperatures of O-type stars imbedded in diffuse nebulae are derived from measurements of Hα and radio fluxes from the nebulae and the apparent magnitudes of the stars. Accurate model atmospheres, with ultraviolet line blanketing where appropriate, are used for the theoretical relation between effective temperature and the ratio of Lyman continuum to visual stellar fluxes. Although there is considerable scatter in the results, an average temperature of 48000 K is found for spectral type O5, 40000 K for O6, and 35000 K for O7.
The stellar temperature scale from O5 to A0
Authors: Hayes D.S.
Published: July 2016

An absolute spectrophotometric calibration of Vega and eleven other standard stars was completed by the author in 1967. This calibration extends from 3200 to 10870 Å, and therefore gives a useful calibration of the Paschen discontinuity as well as the Balmer discontinuity, for which calibrations have been available for some time.

The measured values of the ratio of the size of the Paschen discontinuity to the size of the Balmer discontinuity have been compared with corresponding values predicted by model atmospheres. The comparison shows that LTE models satisfactorily predict the continuum in the wavelength range given above.

A stellar temperature scale has been determined by fitting the measured sizes of the Balmer discontinuity of 43 stars to blanketed model atmospheres. This temperature scale agrees very well with Morton's modified form of the Morton-Adams temperature scale for all except the latest B-stars, for which higher temperatures are predicted.
Photographic magnitudes of 201 stars at 2600 Å
Authors: Sivan Jean-Pierre , Viton Maurice
Published: July 2016

The magnitudes of 201 stars at 2600 Å (1000 Å passband) were derived from two plates of the winter Milky Way obtained with a large field camera. A preliminary investigation of the interstellar reddening allowed us to plot a color-spectral type diagram. Stars of type O seem to be brighter than predicted.
Low resolution stellar spectrophotometric observations in the region 1500 Å–3000 Å
Authors: Sudbury G.C.
Published: July 2016

The success of Stecher and Milligan (1962) in obtaining UV photoelectric objective dispersion spectra of stars in 1962 inspired similar work at the Royal Observatory, Edinburgh. For a number of reasons we preferred to build a system using grating dispersion in the convergent beam from a 21-cm diameter paraboloidal mirror (Sudbury, 1969). The same principle of random sky scan from a spinning rocket was employed.
Ultraviolet photometry of stars from OSO II
Authors: Hallam Kenneth L.
Published: July 2016

Ultraviolet stellar fluxes from 1500 to 3200 Å were from February through August 1965 on OSO II. A 15-cm diameter Gregorian telescope with a stepped grating spectrophotometer provided flux measurements in ten adjacent 180 Å wide band passes.

By comparing fluxes of stars showing B-U color excesses smaller than 0.19 and larger than 0.26, an ultraviolet extinction curve has been derived, which agrees with others which have been published as far as the magnitude effect is concerned, but the shape differs somewhat, the slope at 1/λ = 3.8 μ−1 being somewhat greater than at 1/λ = 5.0 μ−1.

If the stars' fluxes are corrected for reddening, it is found that there is a good agreement between observation and models for stars earlier than B3, but that many of the later type stars have a residual apparently intrinsic reddening.
The ultraviolet solar opacity
Authors: Gingerich Owen
Published: July 2016

Ultraviolet solar observations are compared with predictions from a new solar model. From 3600 to 1700 Å there is heavy line blanketing; probably one or more major sources of opacity are missing from the theoretical calculation in this region.
Observations of ultraviolet stellar spectra
Authors: Wilson R.
Published: July 2016

The dividing line between photometry and spectrometry is not always obvious and for the purpose of this review, I will define ultraviolet stellar spectroscopy as observations with sufficient spectral resolution to allow the detection of individual spectral lines and their measurement in terms of wavelength and strength. From an examination of the existing observations this results in a resolution requirement of δλ < 10 Å. Since the best spectral resolution so far obtained is about 1 Å then this places the results to be discussed within the range 1–10 Å. In terms of λ/δλ this corresponds to a range of about 2000–200 and it is important to bear in mind that these represent low resolution spectra. In fact the limit of 200 that I have imposed would rarely be used for spectroscopic studies in ground based observatories where it corresponds, in the notation of the optical astronomer, to a dispersion of about 1000 Å/mm, the resolution limit being set by the photographic plate, typically taken as 20 μ. Hence, even the faintest objects like quasars are usually studied with a dispersion of a few hundred Å mm−1. The fact that such a resolution can be included here is an indication of the exceptionally strong resonance lines which occur in the ultraviolet and which can be detected with such a resolution. On the other hand, the richness of the ultraviolet spectrum is making and will continue to make, demands on improved resolution in order to separate the many features. The best achieved resolution of about 1 Å goes only part-way to solving this problem.
The far-ultraviolet spectrum of γ Cassiopeiae
Authors: Morton Donald C. , Jenkins Edward B. , Bohlin Ralph C.
Published: July 2016

The ultraviolet spectrum of γ Cas from 1060 to 2120 Å is described.
Mass loss from early-type stars
Authors: Hutchings J. B.
Published: July 2016

Following the detailed study of four very high luminosity OB stars, a survey has been made for spectroscopic evidence of mass loss in a number of early-type supergiants. A list of spectroscopic criteria is given and the mass loss estimates for 24 stars plotted on the HR diagram. The dependence of the phenomenon on spectral type and luminosity is discussed as well as its significance in terms of stellar evolution.
Review of astrophysical conclusions from the UV solar spectra
Authors: Pottasch S. R.
Published: July 2016

A good deal is known about the Sun from the measurement of its spectrum. The measurement of the ultraviolet spectrum has contributed to this knowledge and I shall try to summarize the results and problems of some of these investigations.
The night sky brightness measured from satellites Kosmos 51 and 213
Authors: Dimov N. A. , Severny A. B. , Zvereva A. M.
Published: July 2016

(1)

The minimum measured brightness of the night sky (in the visual region) is about 100 stars of the 10th magnitude per square degree near the galactic poles.

(2)

The ratio of fluxes in the ultraviolet (2300–3000 Å) and visual regions is approximately in agreement with expected theoretical data based on the models of stellar atmospheres for spectral classes B0 to G5 and on the distribution of stars of the different spectral classes over the sky.

(3)

The nature of possible deviations (theory minus observation) is discussed.
Space and ground-based stellar spectrophotometry; a summary
Authors: De Jager C.
Published: July 2016

One of the most important results of the present Symposium is the obvious necessity of close cooperation between ground-based and UV stellar spectral observers. Either of the two observational techniques yields only part of the total information about the stars and the interstellar medium; together they enable the scientist to construct the imposing image of modern stellar spectroscopy that we have seen growing during this Symposium.
Exospheric temperature of Venus from Mariner 5
Authors: Barth Charles A.
Published: July 2016

The Lyman alpha measurements made on the sunlit side of Venus by Mariner 5 showed that the distribution of the radiating hydrogen atoms was governed by two scale heights. A revised model is presented in which the inner or cold distribution is attributed to hydrogen atoms in thermal equilibrium with the thermosphere and the outer or hot distribution is due to hydrogen atoms produced by the photodissociation of molecular hydrogen. The consequence of this interpretation is that the temperature of the dayside thermosphere of Venus is 325 K.
A two-parameter theory for Venus spectra
Authors: Chamberlain Joseph W.
Published: July 2016

An approximate, analytic theory has been developed for the formation of spectral absorption lines in a hazy atmosphere that scatters isotropically and has a homogeneous mixture of scattering and absorbing matter. The behavior – i.e., the curve of growth and the dependence of equivalent width on incident and emergent angles – has been examined for various possible situations, with emphasis on the physical reasons for a particular behavior. It is emphasized that two ratios – essentially the line and continuum absorption coefficients relative to the scattering coefficient – are important in any quantitative theory of the curve of growth and phase variation of the absorption spectrum.
Limb darkening observations of Venus from 5 μ to 18 μ
Authors: Westphal J. A.
Published: July 2016

Limb darkening measurements of the thermal radiation from Venus at 5, 9, 11, 13 and 18 μ are presented. This data, produced by deconvolving the observations with a measured instrumental response function, indicates a complex atmospheric structure which will require careful atmospheric modeling to fully interpret.
Longitudinal variations, the opposition effect and monochromatic albedos for Mars
Authors: Irvine William M. , Higdon James C. , Ehrlich Susan J.
Published: July 2016

Observations of Mars previously reported in 10 narrow bands between 3150 Å and 1.06 μ and in UBV are analyzed for brightness variations which correlate with longitude of the central meridian. Such an effect is found for λ ≥ 5000 Å, with some evidence for such a correlation at λ = 4570 Å. The data are then corrected to the mean (over longitude) brightness and a linear phase curve fitted to those observations with phase angle i ≥ 15°. An opposition effect (anomalous brightening at small phase angles) is found for wavelengths λ ≤ 5500 Å, in contrast to a result previously reported. The magnitude at zero phase, phase coefficient, and monochromatic albedo are computed for Mars as a function of wavelength.
Observations of the martian 1.2 μ CO2 bands
Authors: Barker Edwin S.
Published: July 2016

A method to determine independently the Martian surface pressure from measurements of individual lines in the 1.2030 and 1.2177 μ CO2 bands is presented. Observations obtained during the 1967 apparition and some preliminary results of the 1969 apparition observations yield CO2 abundances near 100 m-atm and surface pressures of 4–8 mb.
High altitude interferometer spectra of Mars
Authors: Fink Uwe , Kuiper G. P.
Published: July 2016

Spectra of Mars were presented which were taken as part of the LPL high altitude program [1] with the NASA CV990 jet. The spectra were taken at about 40 000′ (12 km) altitude. Two sets of five flights each were made around May 1, 1969 and June 1, 1969. In each case the first flight was a Moon comparison flight and the other four were Mars flights, with some Moon if the Moon could be observed.

A 12″ telescope received light from a gyroscopically controlled heliostat and directed it into a Block Associates rapid scan interferometer. (For details see Reference [2].) The interferometer had a resolution of 5 cm−1. The present spectra are, however, only reduced for a resolution of 8 cm−1 due to limitations in our computer operations.

The spectra taken around June 1 are of better quality since Mars was brighter at that time. The CO2 bands at 1.4 μ, 1.6 μ, 2.0 μ, and 2.7 μ all show up very nicely. The isotopic C13 companion band of 003 as well as the ordinary forbidden isotopic band of O16C12O18 (002) can be detected. No water vapor at 1.4 μ or 1.8 μ remains after taking the ratio with the Moon. Some possible trace remains at 2.7 μ. Quantitative analysis as well as reductions of the interferograms to higher resolution are in progress.
Mariner 1969: results of the infrared radiometer experiment
Authors: Münch G. , Neugebauer G. , Chase S. C.
Published: July 2016

The energy radiated by Mars in the wavelength bands 8–12 and 18–25 μ has been measured during the flyby of Mariner 1969 with linear resolution of 50 km at closest approach. From the laboratory energy calibrations and assuming unit emissivity, the temperature of the surface materials has been derived. The main results are summarized as follows:

(a)

The temperatures near the equator (Mariner 6), as function of local time, on the average agree with the values expected on the basis of the gross thermophysical properties of the soil determined from ground-based measurements.

(b)

The temperature fluctuations around their mean seem to correspond to variations in albedo over the classical features of the planet, with the possible exception of one area.

(c)

The lowest temperatures measured by channel 2 of Mariner 7, during the polar swath, were 148 K, while at the edge of the polar cap the temperature was 230 K.

A small amount of instrumental responsivity to off-axis radiation will change these nominal temperatures slightly, in the general sense that the low temperatures, when properly corrected, will decrease by a few degrees, while the high temperatures will increase by a similar amount.
Mariner 6 and 7 television pictures: Preliminary analysis
Authors: Leighton R. B. , Horowitz N. H. , Murray B. C. , Sharp R. P. , Herriman A. H. , Young A. T. , Smith B. A. , Davies M. E. , Leovy C. B.
Published: July 2016

Before the space era, Mars was thought to be like the earth; after Mariner 4, Mars seemed to be like the moon; Mariners 6 and 7 have shown Mars to have its own distinctive features, unknown elsewhere within the solar system.

The successful flyby of Mariner 4 past Mars in July 1965 opened a new era in the close-range study of planetary surfaces with imaging techniques. In spite of the limited return of data, Mariner 4 established the basic workability of one such technique, which involved use of a vidicon image tube, on-board digitization of the video signal, storage of the data on magnetic tape, transmission to the earth at reduced bit rate by way of a directional antenna, and reconstruction into a picture under computer control. Even though the Mariner 4 pictures covered only about 1% of Mars's area, they contributed significantly to our knowledge of that planet's surface and history [1, 2, 15, 17].
The spectrum of Uranus in the region 4800–7500 Å
Authors: Galkin L. S. , Bugaenko L. A. , Bugaenko O. I. , Morozhenko A. V.
Published: July 2016

Spectra of Uranus were obtained with the 122 cm reflector of the Crimean Astrophysical Observatory using the spectrometer of the Main Astronomical Observatory of the Ukrainian Academy of Sciences (Kiev), in March 1969. A photomultiplier (Soviet type 79) was used in a pulse counting mode, and the dispersion of the spectrometer at the camera focal plane was 15 Å/mm.
Spectral Analysis of Gamma Rays with the COS-B Satellite
Authors: Van De Hulst H. C. , Scheepmaker A. , Swanenburg B. N. , Mayer-Hasselwander H. A. , Pfeffermann E. , Pinkau K. , Rothermel H. , Schneider H. , Voges W. , Labeyrie J. , Keirle P. , Paul J. , Bellomo G. , Bignami G. , Boella G. , Scarsi L. , Hutchinson G. W. , Pearce A. J. , Ramsden D. , Wills R. D. , Wright P. J.
Published: July 2016

The ESRO satellite COS-B carries one single experiment aiming at the measurement of arrival direction and energy of celestial gamma rays with energies between 25 MeV and 10 GeV. The experiment is conventional in design and consists of a veto counter, a wire spark chamber, a telescope and an energy calorimeter.

The energy measurement is obtained by a CsI scintillation crystal of 4.7 radiation length thickness. The expected energy resolution at 100 MeV is 50% FWHM. The other detector elements are designed as to cause the least possible degradation of the energy measurement.

The possibilities for the detection of a small contribution of π -origin gamma rays in the presence of a power-law type background spectrum will be discussed.
A Satellite Experiment to Measure the Intensity and the Energy Spectrum of Gamma Rays from Solar Flares in the Range 50–500 MeV
Authors: Bignami G. F. , Bland C. J. , Citterio O. , Dean A. J. , Inzani P.
Published: July 2016

A high energy solar gamma-ray telescope incorporating a lenticular Čerenkov for directional measurement and an energy calorimeter is described. The instrument is included in the payload of the TD-1 ESRO spacecraft to be launched into a sun-pointing orbit during spring 1972. The results of laboratory and accelerator tests are presented and the sensitivity and measurement capability to solar flare gamma rays is discussed.
Progress in the Observational X-Ray Astronomy
Authors: Oda Minoru
Published: July 2016

I shall review recent observational results on discrete X-ray sources and on the diffuse background component. Thus far, approximately forty sources have been reported. It is to be noted that the sources can not be classified in only one or two categories and that there are a variety of the sources. Figure 1 shows the situation.
X-Ray Spectrometry of Galactic Sources in the Energy Range 30–200 keV
Authors: Bui-Van A , Vedrenne G. , Cezac Y. , Bouigue A. , Sabaud L.
Published: July 2016

We describe a detection unit for X-rays in the energy range 30-200 keV of high directivity (2° FWHM). This directivity is obtained by the use of a honeycomb collimator and completed by an efficient passive shielding. The angular resolution of the detector necessitates the use of a solar sensor so as to track the sources observed during the balloon flight and to localize them with an accuracy of 3.8 arc min. This experiment was launched with balloon at Aire-sur-L'Adour and Gap (France) and the results obtained must permit the flux limit detected to be reduced.

The performances of this detector are analysed as well as their consequences in the study of galactic discrete sources.
A New Optical System for Solar Soft X-Ray Spectrophotometry
Authors: Dijkstra J. H. , Werner W.
Published: July 2016

At the Institute of Applied Physics TNO-TH at Delft a strongly off-plane grating mounting has been developed for the soft X-ray wavelength region. In this mounting a parallel beam is incident on the grating surface nearly parallel to the grooves. We found herewith a remarkable improvement of the grating efficiency compared with the grazing incidence perpendicular to the grooves. The focal distance is nearly independent on the wavelength, so scanning of the spectrum can be provided by a simple rotation of the cylindrical grating around the central groove. The exit slit and the detector have fixed positions. The lightspot on the detector cathode does not move and has a moderate size; a standard detector can be used.
A Rocket Payload Using Focusing X-Ray Optics for the Observation of Soft Cosmic X-Rays
Authors: Gorenstein P. , Harris B. , Gursky H. , Giacconi R.
Published: July 2016

A rocket payload utilizing focusing optics has been designed and constructed for the detection and localization of cosmic X-ray sources. The instrument is designed to be used in a scanning mode. The sensitivity of the instrument covers the wavelength bands 80 Å to 44 Å and 20 Å to 10 Å with a total field of view of 2° × 8°. A telescope operating on the principle of grazing incidence reflection instantaneously focuses the X-rays from a distant source in one dimension upon one member of four proportional counter elements located in the focal plane. Location precision from a single scan is about 0.1° × 1° for the stronger sources. The telescope consists of eight nested sheets of re-enforced glass whose reflecting surfaces are overcoated with an evaporated layer of chromium to improve reflection properties at the shorter wavelengths. The effective collecting area of the mirror assembly for on-axis radiation is about 160 cm2 at 80 Å, and 40 cm2 at 10 Å. The focal plane detector is a multiwire proportional counter with a one micron polypropylene entrance window and contains a supply of propane gas regulated to a constant pressure of 50 cm. In the wavelength range 80 Å–10 Å the focusing technique results in (1) greater sensitivity, (2) better angular resolution, and (3) improved detector reliability compared to non-focusing techniques. (Published, Nuclear Instruments and Methods91 (1971) 451.)
A Balloon-Borne X-Ray Telescope
Authors: Fujii M. , Matsuoka M. , Miyamoto S. , Nishimura J. , Oda M. , Ogawara Y. , Ohta S.
Published: July 2016

A balloon-borne X-ray instrument with the modulation collimator was designed and constructed to study the structure of solar X-ray flares. The angular resolution was approximately one arc minute. The instrument was used on an occasion of X-ray flare on Sept. 27, 1970.
Construction of Apodised Zone Plates for Solar X-Ray Image Formation
Authors: Dijkstra J. H. , De Graaff W. , Lantwaard L. J.
Published: July 2016

A Fresnel zone plate (sometimes called a Fresnel-Soret zone plate) is an image formation device consisting of a large number of concentric circular rings which are alternatively transparent and opaque for the radiation concerned.
High Resolution Balloon-Borne Spectrograph for the Near Solar Ultraviolet
Authors: Lemaire P.
Published: July 2016

In order to obtain the solar spectrum of the Mgii lines at 2795.5 Å and 2802.7 Å, we built a balloon instrument which consisted of a Cassegrain telescope, with an aperture ratio of F/20 and a focal length of 300 cm to give a solar image on the slit of a spectrograph. The theoretical spectral resolution is better than 10 mÅ. In the laboratory, we measured a spatial resolution of 10 μ in the image plane of the spectrograph, which corresponds to 1 arc sec in this mounting. During a balloon flight of 1969, April 30, which used a biaxial pointing system, we obtained a spatial resolution better than 10 arc sec, limited by the accuracy of the pointing system. Lastly, on 1970 June 24, the same instrument with a servosystem inside the telescope, was launched and spectral and spatial resolutions of 25 mÅ and about 3 arc sec, respectively, were obtained.
The Princeton Experiment on the Orbiting Astronomical Observatory
Authors: Jenkins E. B.
Published: July 2016

Princeton's 80 cm diameter telescope with an ultraviolet spectrometer will be the prime experiment on board NASA's third Orbiting Astronomical Observatory (OAO-C) which is scheduled for launch in late 1971. Two scanning carriage arms within the spectrometer will each have one photomultiplier sensitive to a 1600–3200 Å first order spectrum and another photomultiplier which will register from 800 to 1600 Å in the second order. Since the primary purpose of the instrument will be to study interstellar absorption lines, the design philosophy has emphasized the role of carefully examining the detail of specific lines, rather than surveying a star's entire spectrum. Thus the carriage with the narrowest exit slits, providing 0.1 Å resolution in first order and 0.05 Å in second order, has been programmed to repetitively scan and retrace over any selected 0.7 Å interval in first order (or 0.35 Å in second order). Stepping motion in one direction every 16 s will occur for the second carriage, which will offer 0.4 and 0.2 Å resolutions for first and second orders, respectively. Approximately half of the starlight which is focussed on the entrance slit jaws is reflected into a fine guidance system which will enable the spacecraft to stabilize to within 0.1 arc sec on a star as faint as 7th magnitude.
Real Time Control of the Observing Program of an Orbiting Solar Observatory
Authors: Reeves E. M. , Huber M. C. E. , Withbroe G. L. , Noyes R. W.
Published: July 2016

This paper departs somewhat from the usual interpretation of the subject of this symposium, in which instrumental techniques normally deal with diverse aspects of experiment design or construction. Rather, we will concern ourselves here with some innovations in the ground control optimization of the modes of data acquisition once an instrument is in orbit. Although the fullest possible utilization of the data gathering capability of a device is of vital interest to the success of the experiment and the mission, the subject has not been discussed at length in the open forum of scientific meetings. The planning of the data gathering and processing aspects of a mission must receive as careful attention as instrument design and test if the characteristics of the instrument are to be fully exploited.
Space Radio-Astronomy of Solar Bursts at All Frequencies: The Stereo Project
Authors: Steinberg J. L. , Caroubalos C.
Published: July 2016

Most observed characteristics of type III bursts are accounted for by the ‘plasma hypothesis’ which implies that the radio energy is radiated from the coronal altitude where the local plasma frequency is close to the observing frequency and the index of refraction vanishes. Strong focusing is to be expected in the absence of scattering effects.
Nutation as derived from latitude observations
Authors: Fedorov E. P.
Published: July 2016

The results of several long series of latitude observations have been used for a separate determination of the coefficients of some nutational terms in obliquity and longitude.

The derived value of the constant of nutation is essentially smaller—and those of the coefficients of the semiannual and semimonthly terms larger—than the respective theoretical values, determined on the supposition that the earth as a whole is an elastic body. The theoretical value of the ratio of the axes of the nutational ellipse evidently does not need any correction.

On the basis of these data some conclusions of a qualitative character are made on the interaction between the core and the shell of the earth.
Variations périodiques et aléatoires de la rotation de la Terre
Authors: Stoyko Nicolas
Published: July 2016

Etude de la periode 1952–1958 a montré la stabilité assez grande de la variation saisonnière de la rotation de la Terre par rapport à l'heure definitive. Nous avons trouvé

où j est exprimé en jours moyens à partir du Ier janvier.

La comparaison avec le temps terrestre des étalons atomiques de fréquence à césium a permis de trouver que la vitesse moyenne de la rotation de la Terre varie d'une façon aléatoire pendant les trois derniéres années. Pour la période du juin au novembre 1955 la durée du jour diminue (la Terre accélere) de 2 × 10−6 sec. par mois, du decembre 1955 au mai 1957 la durée du jour augmente progressivement (la Terre retarde) en moyenne de 4 × 10−6 sec. par mois et à partir du mai 1957 elle est presque constante.

Ainsi, I'extrapolation du temps rotationnel terrestre par rap portau temps atomiques présente des grandes difficultés
Etalons de fréquence
Authors: Decaux B.
Published: July 2016

De récents progrès ont été obtenus sur les horloges à quartz et les étalons atomique de fréquence.

L'amortissement des cristaux a pu être notablement diminué par le choix de tailles spéciales et également par l'emploi de températures voisines du zéro absolu; le vieillissement se trouve en même temps très réduit. L'asservissement d'un oscillateur par un cristal fonctionnant comme résonateur permet d'obtenir une stabilité accrue.

Le résonateur à jet atomique de césium a fourni de remarquables résultats dans divers pays, et a permis d'affectuer des comparaisons internationales montrant un accord à quelques 10-10 près. Des mesures régulières sont effectuées par rapport aux déterminations horaires. Un de ces appareils est réalisé sous forme industrielle.

Le Maser à jet moléculaire d'ammoniac constitue un générateur de courant. Il a donné lieu à de nombreuses réalisations. Certains de ces étalons sont comparés aux horloges d'observatoires, et par l'intermédiaire de signaux horaires, aux étalons à césium. Certaines différences ont été constatées.

Les étalons atomiques de fréquence permettent d'améliorer considérablement la conservation du temps par les horloges à quartz.
Inaugural address Delivered at the I.A.U.-Symposium no. 21
Authors: Fricke W.
Published: July 2016

After a presentation of the problem posed by the construction of a system of astronomical constants, the author describes the new catalogue FK 4. He then reviews recent progress in the knowledge of the orbits of major planets and in the determination of solar parallax, the constant of aberration and the constant of precession.
A preliminary estimation of the accuracy of the inner planet's co-ordinates
Authors: Kulikov D. K.
Published: July 2016

In the construction of analytical theories of planetary motion, the effect is considered of errors in the adopted values of masses, orbital elements and ephemeris time upon the accuracy of computed co-ordinates of the inner planets in accordance with Newcomb's expansions and constants (with Ross's elements for Mars). These are accurate to five decimal places. The errors in the orbital elements are the principal source of inaccuracy in the positions of the planets. The precision of the ephemerides can be considerably improved by introducing appropriate corrections.
Radar determination of the Astronomical Unit
Authors: Shapiro Irwin
Published: July 2016

A comprehensive review is given of the Earth-Venus measurements made with the Lincoln Laboratory Millstone radar in 1959 and 1961. The time-delay and Doppler shift data yield a value for the Astronomical Unit of 499.0052 ± 0.001 light-sec. Using 299 792.5 km/s for the speed of light leads to an AU of 149 598 000 ± 300 km. With the radius of Earth taken as 6 378.15 km, the solar parallax then becomes 8″.79416 ± 0″.00002. This value is consistent with measurements made at various other laboratories to about one part in 105.
Progres recents sur la stabilite des mouvements periodiques
Authors: Janet M.
Published: July 2016

La notion destabilité structurelleest relative au cas oò c'est L'équation même qui varie et non pas seulement les données initiales.
On periodic motions of stars within ellipsoidal stellar systems
Authors: Abalakin V. K.
Published: July 2016

L. Perek

The existence of periodic motions of stars belonging to an ellipsoidal stellar cluster has been proved, the effect of medium resistance being neglected. The density distribution is assumed to depend on the polar semi-axis of the ellipsoidal system, the surfaces of equal density being homothetical ellipsoidal surfaces. By applying Lindstedt–Lyapounov's method of frequency variation the generating solutions have been obtained in an explicit form. Following H. Poincaré's method the first terms of power developments relative to a small parametervhave been found corresponding to several commensurabilities between the mean motion of the star and that of the peri centre of its orbits as well as the angular velocity of rotation of the cluster.
A new solution of Hill's lunar problem
Authors: Stumpff K.
Published: July 2016

The two second order differential equations of Hill's lunar problem for rectangular co-ordinates in the rotating system are transformed into a single equation of the fourth order for the geocentric radius vector r, which can be reduced, using Jacobi's integral, to a differential equation of the third order. A discussion of this equation leads to a new exhibition of Hill's “variation orbits”. The first terms of Hill's power series, which represent these periodic solutions of the problem, are exactly confirmed by using a very simple approximative assumption about the mathematical character of the solution.
Zonal and tesseral harmonic perturbations of an artificial satellite
Authors: Garfinkel B.
Published: July 2016

The paper extends the known solution of the Main Problem to include the effects of the higher spherical harmonics of the geopotential. The von Zeipel method is used to calculate the secular variations of orderJmand the long-periodic variations of ordersJm/J2andnJm,λ/ω. HereJmandJm,λare the coefficients of the zonal and the tesseral harmonics respectively, withJm,0=Jm, andωis the angular velocity of the Earth's rotation. With the aid of the theory of spherical harmonics the results are expressed in a most compact form.
Sur le mouvement d'un satellite autour de la Lune
Authors: Kovalevsky J.
Published: July 2016

Discussion du mouvement d'un satellite lunaire sous l'action des perturbations terrestres et celles qui sont dues aux termes enJ2etJ3du potentiel lunaire. Il existe trois familles d'orbites de libration. Les orbites trouvées sont très perturbées: les satellites de demi-grand axe 2500 km s'écrasent en général sur le sol sauf trois familles d'orbites au voisinage des inclinaisons 0°, 63° et 900.
HST Image Restoration: Current Capabilities and Future Prospects
Authors: Hanisch Robert J. , White Richard L.
Published: July 2016

The spherical aberration in the primary mirror of the Hubble Space Telescope causes more than 80% of the light from a point source to be spread into a halo of radius of 2–3 arcsec. The point spread function (PSF) is both time variant (resulting from spacecraft jitter and desorption of the secondary mirror support structure) and space variant (owing to the Cassegrain repeater optics in the Wide Field / Planetary Camera). A variety of image restoration algorithms have been utilized on HST data with some success, although optimal restorations require better modeling of the PSF and the development of efficient restoration algorithms that accommodate a spacevariant PSF. The first HST servicing mission (December 1993) will deploy a corrective optics system for the Faint Object Camera and the two spectrographs and a second generation WF/PC with internal corrective optics. As simulations demonstrate, however, the restoration algorithms developed now for aberrated images will be very useful for removing the remaining diffraction features and optimizing dynamic range in post-servicing mission data.