bluuebunny/crossref_metadata_2025_split huggingface dataset:
Commission 34. (Solar Parallax.)
Authors: Jones Spencer , Slocum F. 
Published: July 2016

The President first summarized the present position of the work of determining the solar parallax as given in the Report.In connection with the determination of the positions of the reference stars it was stated that within the next six months or so the reductions of all the series of photographs will be completed and it will then be possible to co-ordinate the results and publish a definitive list of secondary comparison stars. At the same time it has become apparent that there are appreciable errors in the positions based on the meridian observations of some of the primary stars given in Prof. Kopff’s catalogue. By co-ordinating the measures of the several series of path plates it will be possible to derive corrections to the positions of the Kopff stars, which will still keep them on the system adopted by Prof. Kopff, but will improve their homogeneity.
9 Commission des Instruments Astronomiques
Authors: Fabry M. Ch , Chrétien M. H. , Anderson MM. , Baillaud R. , Calder  , Chandon Mme , Couder MM. , Danjon  , Pluvinel de la Baume , Delvosal  , Dufay  , Horn d’Arturo  , Moll  , Ritchey  , Sampson  , Schilt  , Svoboda  
Published: July 2016

La commission vient de perdre l’un de ses membres les plus actifs dans l’élaboration et la construction des instruments. Le Dr F. G. Pease est décédé le 7 février 1938, après une très courte maladie qui l’emporta en quelques jours.Mme Ed. Chandon suggère que la commission étudie systématiquement, aux divers points de vues des observations astronomiques, l’œil, cet instrument auquel tous les autres aboutissent et aux imperfections duquel ils doivent remédier.L’œil est un instrument multiple. Ses qualités photométriques et colorimétriques jouent un rôle fondamental dans les observations des étoiles variables. Comme instrument de coïncidences, l’astigmatisme qu’il peut présenter n’intervient pas de la même manière dans les observations des passages, dans les mesures des hauteurs, etc.
19. Commission de la Variation des Latitudes
Authors: Kimura M. , Jones M. H. Spencer , Carnera M. , Bemporad MM. G. , Berg  , Bianchi  , Burton H. E. , Castro H. , da Gama  , Dodwell  , Esclangon  , Lambert W. D. , Matukuma  , Niethammer  , Orlov  , Peres  , Schlesinger  , Schumann  , Sollenberger  , Stetson  , Stoyko  , Subbotin M. , Vocea  , Williams E. L. 
Published: July 2016

In consequence of the decision made by the Fifth General Assembly of the I.A.U. I have been entrusted, from January 1936, with the direction of the Central Bureau for the International Service of Latitudes.I am much indebted to Prof. Kimura, who preceded me as Director and to Prof. Kohlschütter, Director of the Geodetic Institute of Potsdam, for information and advice, which has been of great assistance to me; therefore I desire to acknowledge to them my deep gratitude.
10. Solar Activity
Authors: Švestka Z. , Jefferies J. T. , Kiepenheuer K. O. , Michard R. , Nagasawa S. , Newkirk G. , Rösch J. , Severnyj A. B. , Waldmeier M. , Fokker A. D. 
Published: July 2016

The reader is kindly asked to consider this report for some sort of greatly unbalanced equilibrium between the pressure exercised by the steadily increasing flow of papers discussing the vastly extending subject of solar activity, and the equally steady pressure exercised by the editor who insists on having this report twice as short as three years ago. Therefore, some selection of the subjects and papers had to be made, a fairly severe one, since only about one third of all published papers could have been mentioned in the references, and I am well aware that almost everyone who will read the report, could suggest some improvement of the selection scheme. Nevertheless, I believe that the report as it stands, can fulfill its basic purpose, i.e. to give to the readers a general picture on the progress, which has been achieved in the field of solar activity research since the Prague meeting and on some of the research activities which are in progress at the present time.It is a great pleasure to acknowledge the enormous help I have received from the authors of the individual sections of the Draft Report, as well as from many other members of the Commission, who have very kindly provided me, or the co-authors, with useful information on the recent progress of their work. It is necessary to add that some highly valuable comments made by V. Bumba, J. T. Jefferies, C. Sawyer, E. v. P. Smith, B. Valníček and J. M. Wilcox, have also been included in other chapters than those prepared by themselves.
Working Group on Solar Eclipses
Authors: Rigutti M. 
Published: July 2016

The working Group on Solar Eclipses regrets Dr J. Houtgast’s resignation as Chairman of the Group. However, Dr Houtgast will maintain his membership and continue to give his experience to the group.The total eclipse of September 22,1968 was actively observed by many groups in spite of its short duration. Reports on the observations are expected to be given during the 1970IAU General Assembly.A great deal of work has been done everywhere in view of the total eclipse of March 7, 1970.
15. Physical Study of Comets
Authors: Biermann L. , Vanýsek V. , Herzberg G. , Levin B. J. , Roemer E. , Whipple F. L. , Wurm K. 
Published: July 2016

The partition of the subject matter of this report follows that of earlier reports. Drafts for individual sections or parts of such were contributed by C. Arpigny, L. Biermann, A. H. Delsemme, O. V. Dobrovolsky, L. Haser, G. Herzberg, B. J. Levin, Rh. Lüst, E. Roemer, V. Vanýsek, and K. Wurm. The overall editing was done by Mrs Rh. Lüst, V. Vanýsek, and the undersigned.Before mentioning some of the more important developments it is noted that E. Roemer has continued to publish every few months short notes on comets in the Publications of the A.S.P. The annual reports inQuarterly Journal of the Royal Astronomical Societyhave been continued by B. G. Marsden and J. G. Porter.Several collections of Russian papers have been published which give a survey of the work done in the U.S.S.R. The description of physical characteristics of comets which appeared from 1961— 1965 was continued by S. K. Vsehsvjatskij, who also completed a book onNature and Origin of Comets and Meteoritic Matter.
23. Carte du Ciel
Authors: Dieckvoss W. , Lacroute P. , Couderc P. , Dejč A. N. , Herget P. , Kox H. , Luyten W. J. , Sémirot P. , Wood H. W. 
Published: July 2016

There seems to be a consensus of opinion that the useful life of the commission has come to an end with the achievement of the principal aim of the historical task of the Carte du Ciel, presenting an overall picture of the Heavens as to positions of the fixed stars up to a definite limiting magnitude. The French presidents in succession with great energy, supported by the IAU, succeeded in overcoming all obstacles and in finishing the printed Astrographic Catalogue. Remaining tasks of deriving definitive plate constants, eventually deriving reliable proper motions of all stars in the programme evidently rests with individual observatories or at other commissions of the Union within their proper frame of activities.Following a suggestion presented at the meeting of the Executive Committee in September 1969 a decision was reached to abolish the Commission 23 proper by merging it with Commission 24 (Stellar parallax and proper motion), and a working group in the latter commission would become a suitable means to continue work on data furnished by the Astrographic Catalogue.Several of those observatories still in possession of Carte du Ciel-astrographs are going on with proper motion (p.m.) work in their zones or are preparing to do so. The application of the astrographs to the programme of attachment of stars to galaxies according to A. N. Dejč’s method is in progress.
Working Group on the Magellanic Clouds
Authors: Thackeray A.D. 
Published: July 2016

A Symposium on the Magellanic Clouds was sponsored by E.S.O. in Santiago, Chile, in 1969 March in connection with the dedication of the E.S.O. Observatory at La Silla. Review papers on the Clouds have been written by Westerlund and Bok (J. R. astr. Soc. Can., 63, 105).Gascoigne (Mon. Not. R. astr. Soc., 146, 1) has prosecuted further his P-L work on Cloud cepheids and finds
V = 17·58 — 3·072 logP (7 LMC cepheids),
V = 17·73 — 2·879 logP (13 SMC cepheids)
while 25 SMC, 18 LMC and 13 galactic cepheids obey the Sandage relation
Mv = a – 3·609 logP + 2·52(<B> – <V>).This implies moduli of 18·73 (LMC) and 19·36 (SMC), but Gascoigne recommends, in the light of other evidence, adoption of moduli 18·75 (LMC) and 19·2 (SMC). The colours of SMC cepheids are 0.m1 bluer than those in the Galaxy and they may be somewhat underluminous for their periods.
29a. Working Group on Absolute Spectrophotometry
Authors: Oke J. B. 
Published: July 2016

Two new and independent determinations of the absolute spectral energy distribution in αLyr have been completed during the last three years. The first of these by Hayes has been published in part (Wolff, Kuhi and Hayes, 1968). It was done at the Lick Observatory using the Crossley reflector and two ribbon-filament standard lamps. His published results are based on the old practical temperature scale which is based on a melting point for gold of 1336·16K. The new scale has been adjusted to agree as well as possible with the thermodynamic temperature scale and is based on 1337·59K for the melting point of gold. Hayes’ results have been adjusted to this new scale and are shown in Table 1. The numbers listed are — 2·5 log fv + const, when fv is the flux from αLyr in ergs s-1 cm-2 Hz-1. The results are normalized to 0·000 at λ5556.The new calibration by Oke and Schild was carried out on Palomar Mountain. A four inch reflecting telescope was built and mounted with the prime focus scanner which was built for the 200-inch telescope. Three light sources were used (1) a ribbon-filament standard lamp calibrated with an accuracy of 2 % by the National Bureau of Standards was used from λ3300 to λ8000.
45. Spectral Classifications and Multi-Band Colour Indices
Authors: Fehrenbach Ch. , Westerlund B. , Bidelman W. P. , Haradze E. K. , Jaschek C.O.C. , Johnson H. L. , Morgan W. W. 
Published: July 2016

Des classifications spectrales et des mesures photométriques ont été faites dans de nombreux Observatoires.La classification à un seul paramètre, comme celle de Harvard, a été remplacée dans la plupart des cas par une classification bidimensionelle. La classification simplifiée est réservée aux étoiles faibles. Les classifications dans le système MK ont été faites dans de nombreux Observatoires et nous signalons les importantes listes d’Abastumani.De nombreux astronomes ont recherché les étoiles riches ou pauvres en métaux, ce qui est l’amorce des classifications à trois paramètres. Des listes d’étoiles Am et Ap ont été publiées.
10. Distribution of electron concentration with
height and its influence on the propagation of
radio waves
Authors: Zhekulin L. A. 
Published: July 2016

AbstractIn this paper there is investigated the propagation of radio waves in a non-homogeneous ionized atmosphere with a dispersion of ionization obtained as a result of recent investigations into the structure of the ionosphere.On the basis of the wave treatment of the problem, relations were found for the electric field intensity, expressed as Airy functions; and the results were compared with the approximate solution by geometric optics.
Improving the Accuracy of Radio Astrometry
Authors: Fey Alan L. 
Published: July 2016

AbstractThe International Celestial Reference Frame (ICRF) is currently realized by the radio positions of compact extragalactic objects obtained by the technique of Very Long Baseline Interferometry (VLBI). The positions of the defining sources with the highest quality are estimated to be accurate at the 0.25 milliarcsecond (mas) level. The limiting accuracy is thought to be due mostly to tropospheric propagation effects and by the apparent motions of the sources due to variable intrinsic structure. Increasing the accuracy of VLBI astrometry beyond current levels will require an improved understanding of the variable emission structures associated with compact extragalactic sources as well as improvements in the modeling of the Earth’s troposphere.
Densification of ICRS in the Optical by use of Old Pulkovo Observation Sets
Authors: Kumkova Irina I. , Bobylev Vadim V. , Bronnikova Nina M. 
Published: July 2016

AbstractModern tasks of high precision astrometry demand optical coordinate systems including more faint stars than are available now in current conventional systems (Hipparcos). For this purpose it is suggested to use old photographic observations accumulated in the Pulkovo Observatory. Extensive observational data have been obtained at Pulkovo Observatory during the last century in the framework of several programs, e.g. Pulkovo Galaxy plan, etc. Observations have been made with the Normal Astrograph from 1894 to the present. The data are investigated with the aim of extending the Hipparcos catalog to stars fainter than 11th magnitude. All available observations are taken into account. A description of the material considered is given. The distribution of the selected plates over the celestial sphere is shown as well. Coordinates of faint stars in the Hipparcos system are calculated for selected areas. The accuracy of computed star coordinates is analyzed. Results of the investigation are presented.
A New Optical Realization of the ICRS
Authors: Gontcharov George A. , Andronova Anna A. , Kornilov Edward V. , Titov Oleg A. 
Published: July 2016

AbstractA new optical realization of the ICRS is built upon the data of the Hipparcos catalog and 60 observational and compiled astrometric ground-based catalogs of the 20th century reduced to the Hipparcos system. It is in print as two catalogs. The ‘Proper Motions of Fundamental Stars’ catalog (PMFS) contains proper motions of 4638 stars common to the Hipparcos and Basic FK5/FK5 Extension improved to the level of 0.5 mas. 1800 of the stars are the photocenters of stellar systems unresolved in the astrometric observations. The duplicity parameters of those systems were collected in the ‘Astrometric Binaries’ catalog (ABC). The photocenter nonlinear motions of several hundred of those astrometric binaries were detected and separated from their proper motions. The periods and amplitudes of several astrometric binaries are discussed in detail. This research will be continued for all Hipparcos stars observed from the ground in the 20th century. The web site is http://www.geocities.com/georgegontcharov/
On the Reference Pole for Earth Orientation and UT1
Authors: Mathews P.M. , Herring T.A. 
Published: July 2016

AbstractWe show how the study of variations in orientation of a terrestrial reference system (TRS) in space may be done directly in terms of the motion of the pole of the TRS and rotation around it, and how a separation of these variations into low frequency and high frequency (retrograde and prograde diurnal, semidiurnal, · · · ) bands enables one to characterize and model variations belonging to the various bands and to estimate them simultaneously from observational data by a uniform procedure. Introduction of the Celestial Ephemeris Pole (CEP) or other Celestial Intermediate Pole (IP) is not only unnecessary, but also gives rise to needless debate as to whether variations due to particular causes are to be included in the celestial motion of the IP or in its terrestrial motion, and leaves the question of estimation of high-frequency signals in either frame unresolved. In regard to UT1, we point out that the “correction terms” through which the concept of the nonrotating origin is implemented emerge naturally from fundamental kinematical relations, and use this observation to identify the correction terms to be employed when the Earth orientation parameters are defined in relation to the pole of the TRS rather than an IP.
A New Nutation Model Of Nonrigid Earth With Ocean And Atmosphere
Authors: Huang Cheng-li , Jin Wen-jing , Liao Xing-hao 
Published: July 2016

AbstractBy integrating the truncated complex scalar gravitational motion equations for an anelastic, rotating, slightly elliptical Earth, the complex frequency dependent Earth transfer functions are computed directly. Unlike the conventional method, the effects of both oceanic loads and tidal currents are included via outer surface boundary conditions, all of which are expanded to second order in ellipticity. A modified ellipticity profile in second order accuracy for the non-hydrostatic Earth is obtained from Clairaut’s equation and the PREM Earth model by adjusting both the ellipticity of the core-mantle boundary and the global dynamical ellipticity to modern observations. The effects of different Earth models, anelastic models, and ocean models are computed and compared. The atmospheric contributions to prograde annual, retrograde annual and retrograde semiannual nutation are also included as oceanic effects. Finally, a complete new nutation series of more than 340 periods, including in-phase and out-of-phase parts of longitude and obliquity terms, for a more realistic Earth, is obtained and compared with other available nutation series and observations.
Influence of Adopted Nutation Model on VLBI NEOS-Intensives Analysis
Authors: Titov Oleg 
Published: July 2016

Very Long Baseline Interferometry (VLBI) provides information about the Earth’s rotation. Various observational programs have operated for different specific purposes since 1983. The purpose of the NEOS-Intensive program is to make observations of Universal Time (UT1–UTC). Short observational sessions (1-2 hours) include only the transcontinental baseline (Wettzell - NRAO20). 20–30 individual scans are performed during the observational time. Only five parameters, wet delay for the reference station, wet delay for the second station, clock offset for the second station, clock rate for the second station, and UT1–UTC are considered in the parametric model.The purpose of this paper is to investigate the influence of the adopted nutation model on the UT1–UTC estimates. VLBI data from the NEOS-Intensives have been analyzed using the OCCAM 3.4 software. All reduction calculations are in accordance with the IERS Conventions 1996 (McCarthy, 1996).
Report on Astronomical Constants
Authors: Fukushima Toshio 
Published: July 2016

AbstractRecent progress in the determinations of astronomical constants is reviewed. First is the latest estimation of the general relativistic scale constants, LC, LG, and LB (Irwin and Fukushima, 1999). By reestimating the uncertainty, the value of the first constant is given as LC = 1.480 826 867 4 × 10–8 ± 1.4 × 10–17. Also noted is the rigorous relation among these three, LB = LC + LG – LCLG. Based on the latest determination of the geoidal potential W0 in the IAG 1999 Best Estimate of Geodetic Parmeters (Groten, 1999), LG and LB were reevaluated as LG = 6.969 290 09 × 10–10 ± 6 × 10–18 and LB = 1.550 519 767 3 × 10–8 ± 2.0 × 10–17. Since LG is roughly related to W0, a proposal to fix its numerical value is presented in order to remove the geophysical ambiguity in its evaluation in the future. In that case, LG becomes a defining constant for the scale difference between the geocentric and terrestrial coordinate systems. While LC and LB remain as a primary and derived constant, respectively. Next is the correction to the current precession constant, Δp. The recent estimates of Δp based on Very Long Baseline Interferometry (VLBI) observation seem to converge to a value close to –0.30″/cy (Mathews et al., 2000; Petrov, 2000; Shirai and Fukushima, 2000; Vondrák and Ron, 2000). Unfortunately this is significantly different from –0.34″/cy, the latest value determined from the Lunar Laser Ranging (LLR) data (Chapront et al., 1999). The difference is roughly ten times larger than the sum of their formal uncertainties. Since the cause of this difference is not clear, we first arranged the best estimates based on VLBI and LLR techniques, respectively, then took a simple mean of these two best estimates, and recommend it as the current best estimate. The value derived is p = 5 028.78 ± 0.03 ″/cy. Similar estimates were given for some other quantities related to the precession formula; namely the correction to the obliquity rate of the IAU 1976 precession formula (Lieske et al., 1977), Δε1 = (–0.024 5 ± 0.002 5) ″/cy, and the offsets of the Celestial Ephemeris Pole of the International Celestial Reference System, Δψ0 sin ε0 = (–17.5 ± 0.8) mas and Δε0 = (–5.2 ± 0.4) mas. As a result, the obliquity of the ecliptic at the epoch J2000.0 was estimated as ε0 = 23°26′21.″405 6 ± 0.″000 5. The draft IAU 2000 File of Current Best Estimates of astronomical constants, that is to replace the 1994 version (Standish, 1995) or maybe even the formal IAU 1976 System of Astronomical Constants (Duncombe et al., 1977), after discussion at the 24th General Assembly of the IAU is presented.
Incompressible MHD Turbulence
Authors: Goldreich Peter 
Published: July 2016

AbstractThe inertial range of incompressible MHD turbulence is most conveniently described in terms of counter propagating waves. Shear Alfvén waves control the cascade dynamics. Slow waves play a passive role and adopt the spectrum set by the shear Alfvén waves. Cascades composed entirely of shear Alfvén waves do not generate a significant measure of slow waves. MHD turbulence is anisotropic with energy cascading more rapidly along k⊥ than along k‖. Anisotropy increases with k⊥ such that the excited modes are confined inside a cone bounded by . The opening angle of the cone, , defines the scale dependent anisotropy. MHD turbulence is generically strong in the sense that the waves which comprise it are critically damped. Nevertheless, deep inside the inertial range, turbulent fluctuations are small. Their energy density is less than that of the background field by a factor θ2(k⊥) « 1. MHD cascades are best understood geometrically. Wave packets suffer distortions as they move along magnetic field lines perturbed by counter propagating wave packets. Field lines perturbed by unidirectional waves map planes perpendicular to the local field into each other. Shear Alfvén waves are responsible for the mapping’s shear and slow waves for its dilatation. The former exceeds the latter by θ−1 (k⊥) » 1 which accounts for dominance of the shear Alfvén waves in controlling the cascade dynamics.
Looking into Pulsar Magnetospheres
Authors: Lyutikov Maxim 
Published: July 2016

AbstractDiffractive and refractive magnetospheric scintillations may allow direct probing of the plasma inside the pulsar light cylinder. The unusual electrodynamics of the strongly magnetized electron-positron plasma allows separation of the magnetospheric and interstellar scattering. The most distinctive feature of the magnetospheric scintillations is their independence of frequency. Diffractive scattering due to small scale inhomogeneities produces a scattering angle that may be as large as 0.1 radians, and a typical decorrelation time of 10−8 seconds. Refractive scattering due to large scale inhomogeneities is also possible, with a typical angle of 10−3 radians and a correlation time of the order of 10−4 seconds. Some of the magnetospheric propagation effects may have already been observed.