bluuebunny/crossref_metadata_2025 huggingface dataset:
Commission 19: Rotation of the Earth: (Rotation de la Terre)
Authors: McCarthy Dennis D. , Capitaine Nicole , Arias F. , Beutler G. , Brosche P. , Brzezinski A. , Dehant V. , Feissel M. , Gross R. , Manabe S. , Morrison L.V. , Rykhlova L.V. , Tarady V. K. , Vondrak J. , Wilson C. , Yang F. , Yatskiv Y.S.
Published: July 2016

The triennial report of Commission 19 was composed from the contributions of its members. Space does not permit a listing of their names, but their contributions are sincerely appreciated. Unfortunately because of limited space it is also not possible to provide in this report the extensive list of publication of the Commission members. The list of publications is however available on the Commission 19 web site at maia.usno.navy.mil/iauc19.
Division III: Planetary Systems Sciences: (Sciences des Systemes Planetaires)
Authors: A’Hearn Michael F. , Baggaley W. J. , de Bergh Catherine , Bowyer Stuart , Hanner Martha S. , Leinert Christoph , Marov Mikhail , Rickman Hans , Tarter Jill , Williams Iwan P. , Yeomans Donald K. , Zappala Vincenzo
Published: July 2016

Because the division consists of many very active commissions, most activities are included in the reports of the individual commissions. This report highlights a small subset of the major achievements that are covered in detail in the reports by the commissions. Some administrative activities of the division and reports of the divisional working groups and committees are also included as subsequent sections of this divisional report.
Commission 16: Physical Study of Planets and Satellites: (Etude Physique des Planetes et des Satellites)
Authors: de Bergh C. , Cruikshank D.P. , Coradini A. , Belton M.J.S. , Blanco C. , Consolmagno G.J. , Gautier D. , McGrath M.A. , Noll K.S. , Owen T.C. , Teifel V.G. , Woszczyk A.
Published: July 2016

This report includes some of the major achievements in studies of planets and satellites that have been made during the past three years.
Commission 36: Theory of Stellar Atmospheres
Authors: Traying G. , Gustafsson B. , Frisch H. , Hearn A.G. , Kalkofen W. , Kodaira K. , Marlborough J.M. , Mihalas D. , Sapar A.A. , Seaton M.J. , Underhill A.B.
Published: July 2016

Commission 36 acts as a cosponsor of the following Symposia: (1) IAU Symposium No. 102 “Solar and Stellar Magnetic Fields: Origin and Coronal Effects” Zurich, Switzerland (2-6 August 1982) and (2) IAU Symposium No. 103 “Planetary Nebulae” London, UK (10-1U August 1982). The commission participates jointly with Commissions 29, 35, and 45 in the organization of a Joint Discussion at the IXth General Assembly on the topic “Mass-Loss-Phenomena”.
7 – Celestial Mechanics
Authors: Kovalevsky J. , Brumberg V. A. , Aksenov E. P. , Chapront J. , Ferraz-Mello S. , Hadjidemetriou J. , Henrard J. , Jefferys W. H. , Kozai Y. , Scholl H. , Seidelmann P. K. , Sinclair A.
Published: July 2016

Celestial Mechanics has undergone, in the past three years, a considerable development that has been marked by a significant increase of published papers and by the recent organization of several specialized colloquia or symposia. The reasons of this increase of interest may be found among the following circumstances:

-

The discovery of new dynamical situations in the Solar system: ellipticity of ringlets, shepherd satellites.

-

The increase of interest in the problem of the dynamical evolution of the solar system or of its subsystems.

-

The present necessity to include relativistic effects in the theory of motion of celestial bodies.

-

New promising results in the analysis of the properties of dynamical systems.
VI. Solar Radiophysics
Authors: Stewart R. T.
Published: July 2016

The past 3 years since the last solar maximum have witnessed an unprecedented number (>200) of published scientific papers on many aspects of solar radiophysics. These contributions are the result of an intense research effort mounted during the first Solar Maximum Mission of 1980 and continued until the present. Excellent x-ray, EUV, and visible light observations of the disturbed corona and transition region have been obtained from the SMM, Hinotori, P78-1, and ISEE-3 spacecraft. ISEE-3 also has provided very low-frequency radio observations of solar bursts in the interplanetary medium. Ground-based radio support for space experiments has been provided by many observatories throughout the world. In particular, many collaborative studies using x-ray and radio observations of solar flares have been reported. The outstanding radio instrument during this period has been the VLA, operating at 2, 6, and 20 cm with a time resolution of 10 s and both modes of circular polarization. The two-dimensional spatial resolution of the radio images is a few seconds of arc, almost as good as the best resolution obtained so far at any wavelength in the solar spectrum. To complement the rather poor time resolution of the VLA one-dimensional arrays such as the WSRT at 6 cm wavelength and the Nobeyama interferometer at 17 GHz have been used successfully. In addition, a number of very-high-time resolution radiometers have been built at different locations. At meter wavelengths two-dimensional arrays at Clark Lake, Culgoora, and Nancay and a one-dimensional array at Nobeyama have been employed. The little known region of the solar spectrum at decimeter wavelengths is being investigated by the Zurich spectrograph. It is pleasing to see Chinese participation in solar radiophysics.
Commission 14: Atomic and Molecular Data
Authors: Gabriel A. H. , Nicholls R. W. , Johnson D. R. , Mandel’shtam S. L. , Nussbaumer H. , Phillips J. G. , Sahal S. , Takayanagi K. , Wiese W.
Published: July 2016

As the pool of fundamental data available to astronomers continues to increase, the question of how best to promote the necessary cross-discipline interaction becomes increasingly important. Commission 14 has traditionally played an important role in this activity, by publishing triennial reports in the IAU Proceedings, as well as by responding to more specific requests for data. We are fortunate in having the support for these activities of some energetic Working-Groups and Chairmen, whos contributions to the present report are very gratefully acknowledged. With the expansion of available data it is appropriate that these reports take on more and more the form of references to review articles and other more specific data bases. The question of whether the field of activity of the Commission should be enlarged was discussed at Patras and will be reviewed again at the Delhi meeting. One possibility is to include nuclear processes and fundamental particle physics. On the other hand a rationale for limiting the scope of our activities might be the direct application to astronomical observations. Astronomical theorists are usually better placed to access the fundamental data themselves. The interaction between fundamental physics and astronomy will in general take two forms. There is the essential service role of making data available in a usable form. However, we should surely aim to stimulate the other very profitable mode, in which the two disciplines are brought together to form real scientific collaborations, in order to research the problems of astronomy.
Working Group 5: Molecular Spectroscopy
Authors: Nicholls R. W.
Published: July 2016

Research in molecular spectroscopy over much of the electromagnetic spectrum has continued intensively over the past three years. It has been stimulated not only by the imperatives of fundamental research programmes in many laboratories, but also by the impact of molecular lasers on the field, and the needs of atmospheric and environmental programmes. The literature is so prolific that it is impossible even to review briefly here all that is relevant to astrophysical needs. Thus most of this report has been compiled from the contributions from individual workers and Research Centres.
16. Physical Study of Planets and Satellites
Authors: Tejfel’ V. G. , Hunt G. E. , Brahic A. , Beebe R. F. , Bertaux J. L. , Elliott J. L. , Gautier D. , Ksanfomaliti L. V. , Marov M. Y. , Masursky H. , Neukum G. , Owen T. C. , Shevchenko V. V. , Smith B. A.
Published: July 2016

During past three years from 1982 to 1984 we saw the further progress in the planets and satellites research by the space and ground-based technique, in the analysis and interpretation of the observational data. Inspite of some decrease of the activity in the planetary spacecrafts launches during this period (except of two Soviet missions to Venus) many important scientific results were obtained from the continued reduction and analysis of the measurements which were performed by Mariner 10 (Mercury), Pioneer Venus, Venera 13 and 14, Viking (Mars), Pioneer 10 and 11, and Voyager 1 and 2.
28. Galaxies
Authors: Rubin V. C. , der Kruit P. C. van , d’Odorico S. , Einasto J. , Graham J. A. , Hodge P. W. , Karachentsev I. D. , Lynden-Bell D. , Toomre A. , Ulrich M. -H. , Wakamatsu K. -I. , Westerlund B. E.
Published: July 2016

The present Report covers the period 1982-1984. As with previous Reports, it has not been possible to cover all publications or even every field of research. Some subsections of this Report, the Magellanic Clouds for example, report a body of work as extensive as that in some commissions.
31. Time
Authors: Hemmleb G. , McCarthy D. D. , Blinov N. S. , Costain C. C. , Fliegel H. F. , Guinot B. , Iijima S. , Miao Y. R. , Orte A. , Paquet P. , Pilkington I. , Proverbio E.
Published: July 2016

This report will try to review briefly the work achieved from 1982 to 1984 in different “subjects to be considered by Commission 31 Time” as adopted in Grenoble 1976. It contains also information provided by Commission members, for which hearty thanks are to be given. The limitation of space required the abbrevation of some institution reports.
50. Identification and Protection of Existing and Potential Observatory Sites
Authors: Hoag A. , van den Bergh S. , Anguita C. A. , Ardeberg A. L. , Bertola F. , Blanco V. M. , Cayrel R. , Crawford D. L. , Edwards P. J. , Mattig W. , Smith F. G. , Walker M. F.
Published: July 2016

While a number of site testing campaigns are in progress throughout the world, the dominant efforts seem to be associated with plans for very large telescopes. These plans, improved telescope technology, and the realization that astronomical observations from space will put increasing demands on ground-based observing facilities have given new impetus to site identification and to the optimum utilization of existing sites. A most excellent review of the factors involved in site identification is now available in the Proceedings of the ESO Workshop on Site Testing for Future Large Telescopes, edited by A. Ardeberg and L. Woltjer 1981. These Proceedings and Woolf’s review (1982, Ann. Rev. Astron. Astrophys. 20 367) provide a solid background of current site evaluation factors.
V. Heating and Dynamics of Chromosphere and Corona
Authors: Brueckner G.E.
Published: July 2016

The crucial role of magnetic fields in any mechanism to heat the outer solar atmosphere has been generally accepted by all authors. However, there is still no agreement about the detailed function of the magnetic field. Heating mechanisms can be divided up into 4 classes: (I) The magnetic field plays a passive role as a suitable medium for the propagation of Alfvén waves from the convection zone into the corona (Ionson, 1984). (II) In closed magnetic structures the slow random shuffling of field lines by convective motions below the surface induces electric currents in the corona which heat it by Joule dissipation (Heyvaerts and Priest, 1984). (Ill) Emerging flux which is generated in the convection zone reacts with ionized material while magnetic field lines move through the chromosphere, transition zone and corona. Rapid field line annihilation, reconnection and drift currents result in heating and material ejection (Brueckner, 1987; Brueckner et al., 1987; Cook et al., 1987). (IV) Acoustic waves which could heat the corona can be guided by magnetic fields. Temperature distribution, wave motions and shock formation are highly dependent on the geometry of the flux tubes (Ulmschneider and Muchmore, 1986; Ulmschneider, Muchmore and Kalkofen, 1987).
Commission 22: Meteors and Interplanetary Dust (Meteores et la Poussiere Interplanetaire)
Authors: Keay C. S. L.
Published: July 2016

As usual, a number of members of the Commission have contributed reviews of their own field. These have been edited in order to reduce overlaps and keep the whole report within the size limitation. Reference numbers from “Astronomy and Astrophysics Abstracts” have been used when available, and those references not (or not yet) included in the “Abstracts” have been gathered into a list at the end of the report. As editor, the President takes responsibility for any shortcomings in the report.
Commission 41: History of Astronomy (Histoire de L’Astronomie)
Authors: North J.D. , Débarbat S.
Published: July 2016

During the XXth General Assembly the Commission agreed to support a motion by Commissions 19 and 31 that a history be prepared of the Bureau Internationale de l’Heure and the International Polar Motion Service; the rider wad added that the two authors proposed (B. Guinot and S. Yumi) obtain the services of a professional historian of astronomy, to advise and assist where possible.
Working Group for Planetary System Nomenclature (Group De Travail Pour La Nomenclature Du System Plametaire)
Authors: Aksnes K. , Brahic A. , Fulchignoni M. , Marov M. Ya. , Morrison D. , Owen T.C. , Shevchenko V.V. , Smith B.A. , Boyce J.M. , Burba G.A. , Masson P. , Millman P.M.
Published: July 2016

It is with great sadness that we have to report the death on 24 August 1990 of the WG’s President, Harold Masursky, at the age of 66. Dr. Masursky is known for his many contributions in planetary science and for his many years of dedicated work in planetary nomenclature. During the interim until the next IAU General Assembly the IAU Executive Committee has appointed K. Aksnes as Acting President of the WG.
10 Solar activity
Authors: Engvold Oddbjørn , Deubner Franz-Ludwig , Ripken Hartmut
Published: July 2016

The time period covered by this report (1 July 1993 - 30 June 1996) has seen the flawless launch and operation of SOHO, the full development of the Global Oscillation Network (GONG) and other seismology networks, a continued successful operation of YOHKOH, the southern and northern passages of ULYSSES, as well as significant advances in high resolution solar observing techniques.

The topics of the present report have been chosen with the aim to maintain a long-term balance in the coverage of activities of the three Commissions, ranging from instrumentation and observing techniques to the most important work and new scientific results from studies of the Sun and Heliosphere. It is our intention to provide critical reviews of the field, which may also be useful for the non-specialist reader.
3. Commission Des Notations, Des Unites Et De L’Economie Des Publications
Authors: Strömgren B.
Published: July 2016

At the Stockholm meeting of I.A.U. in 1938 the General Assembly at the recommendation of Commission 3 adopted a list of notations proposed by the Commission. The list was published in the Transactions of the I.A.U., 6, 345-55, 1938.

It would appear desirable now to reconsider the list, and the problem of standardization of astronomical notation.

A survey of astronomical papers and publications that have appeared after the adoption of the list of notations, with a view to determining to what extent standardization has been achieved, might be useful as a guide to future work of the Commission in this field.
10. Commission Des Taches Solaires Et Des Nombres Caracteristiques
Authors: Waldmeier M. M.
Published: July 2016

Introduction. Ten years have passed since the last Congress and so much has been published since then in the field of photospheric and allied phenomena that this can only be a summary and not an exhaustive report.

Periodicity of Sunspot Activity. The long period already established by R. Wolf in 1862, has again been investigated by W. Gleissberg (Publ. Istanbul Obs. No. 14, 1941; No. 15, 1941; Z. Ap. 21, 347, 1942; Ap. J. 96, 234, 1942), with the result that the period amounts to approximately 70 years.
3. The Chemical Composition of Stellar Atmospheres
Authors: Unsöld A.
Published: July 2016

The quantitative analysis of stellar atmospheres requires—if we may put it somewhat paradoxically—already considerable knowledge of their composition and structure. In practice it is therefore necessary to begin with the simplest problems and even there to proceed in successive approximations.
Commission No. 15: Physical Study of Comets, Minor Planets and Meteorites (Etude Physique des Cometes, des Petites Planetes et des Meteorites)
Authors: A’Hearn M. , Kresak L. , Rahe J.
Published: July 2016

Tribute is paid to those members of Commission 15 who have passed away since the last General Assembly: Dr. Ludwig BIERMANN, Dr. Nicholas BOBROVNIKOFF, Dr. Richard Heinrich GIESE, Dr. Marie-Therese MARTEL, Dr. Reginald WATERFIELD.

The Commission had one Business Session, two Science Sessions on “News in Cometary Research” (organized by C. Arpigny), one Science Session on “News in Minor Planet Research” (organized by A.W. Harris), a Joint Discussion with Commission 20 on “Major Observing Programs and Data Bases” (organized by Y. Kozai and L. Kresak), and a Joint Discussion with Commission 22 on “Interrelation of Meteor Streams, Comets and Asteroids” (organized by P. Babadzhanov and L. Kresak)
17. Commission de Nomenclature Lunaire
Authors: Brown M. E. W. , Adams M. W. S. , Blagg Mlle , Campbell MM. W. W. , de Sitter  , Deslandres  , Dyson  , Müller K. , Pickering W. H. , Strömgren E. , Wright F. E.
Published: July 2016

A sub-committee, consisting of Miss M. A. Blagg and Dr K. Müller, has been at work during the past twelve months on the preparation of a list of names and designations for the lunar formations. This work is practically complete but as it was received by the chairman as late as August 22 it has not been possible for him to do more than glance over it. This brief report by him is therefore merely a summary of their work and of the material which is ready for action by the Commission.
25. Commission de Photométrie Stellaire
Authors: Seares M. F. H. , Baade MM. , Baillaud J. , Bemporad  , Bergstrand  , Graff  , Greaves  , Green  , Hassenstein  , Hellerich  , Hertzsprung  , Jones  , Malmquist  , Pannekoek  , Payne Mile , Ross MM. , Rougier  , Sampson  , Shapley  , Vanderlinden  , Van Rhijn  , Von Zeipel
Published: July 2016

Much material extending our knowledge of stellar magnitudes has accumulated during the last four years. In the appendix to this report will be found a list of recent catalogues, a summary of the discussion made at Mt Wilson by Seares and the formulae that he finds for the reduction of these catalogues to a fundamental system, until such time as a more extended discussion shall have furnished definitive corrections.
16. Commission Pour les Observations Physiques des Planètes, des Comètes et des Satellites
Authors: Phillips T. E. R. , Andrea MM. , Antoniadi  , Armellini  , Baldet  , Bobrovnikoff  , Campbell L. , Delporte  , Doniteli  , Dunham  , Gastardi  , Harwood Mile , Jarry-Desloges MM. , Lampland  , Luplau-Janssen  , Lyot  , Maggini  , Nicholson  , Peek  , Pickering W. U. , Plakidis  , Quénisset  , Ross  , Slipher E. C. , Slipher V. M. , Stroobant  , Wildt  , Wright F. E. , Wright W. H.
Published: July 2016

The following work embodying researches coming within the scope of this commission has been published since the last meeting of the Union: La Planète Mercure et la Rotation des Satellites, by E. M. Antoniadi; Gauthier-Villars, Paris.

In addition to references to the work of other astronomers the author gives a summary of his own observations with the 0.83 m. refractor at Meudon and his conclusions.

The following Memoirs or papers not specifically referred to in the body of the Report have also been published since the last meeting of the Union: Cometa Halley. Vol. xxv of Resultados del Observatorio Nacional Argentino. This is a monograph on the Comet at its 1910 return. By C. D. Perrine. Les Comètes en 1930,1931 et 1932. By F. Baldet. (L’ Astronomie 46,497 et 48,175.) I Fondamenti Psicologici dell’ Indagine Visuale. By M. Maggini. (Memorie dellaSoc. Astron. Italiana, Vol. VIII, 2.) Théorie Photométrique des Eclipses de Lune. By F. M. Link. (Bulletin Astronomique,

8 fase. 11.) Relative Lunar Heights and Topography by means of the Motion Picture Negative.
Commission 5. (Bibliography.)
Authors: Stroobant M. P. , Bourgeois M. P.
Published: July 2016

M. Stroobant estime que les questions soulevées à ce sujet par MM. Dittrich, Brasch et Pogo sont du ressort de la Commission 2; cette Commission devant les difficultés matérielles que présentait pareille entreprise sous les auspices de l’U.A.I. a cessé son activité au Congrès de Rome (1922).

M. Lundmark estime que la question est importante, qu’il convient que l’U.A.I. s’y intéresse et que la Commission s’en occupe.

M. Collinder considère, d’expérience personnelle, que parfois, tout au moins en ce qui concerne certains ouvrages anciens importants au point de vue historique, une publication partielle serait suffisante.
Commission 6. (Telegrams.)
Authors: Strömgren E. , Hansen J. M. Vinter
Published: July 2016

At its meeting the Commission adopted the cipher code for astronomical telegrams, proposed by the President, with two minor alterations, and agreed that the new code was to be used from 1935 Nov. 1. The corrected cipher code is given below in this volume (p. 391).

The Commission also asked for an annual grant of 1200 Swiss francs to the Bureau of Astronomical Telegrams until the next meeting of the Union.

(A joint discussion with Commission 20 is reported by the latter Commission. p. 309.)
14. Commission des Étalons de Longueur D’Onde et des Tables de Spectres Solaires
Authors: Meggers M. W. F. , Babcock MM. , Buisson  , Burns  , Fabry Ch. , Fowler A. , Harrison  , Kayser  , Nagaoka  , Pérard
Published: July 2016

The red radiation, 6438.4696 A., emitted by a cadmium lamp of Michelson type was first chosen in 1907 by the International Union for Co-operation in Solar Research (Trans. I.U.S.R. 2, 109, 1907) as a definition of the unit of wave-length. This primary standard was subsequently adopted by the International Astronomical Union (Trans. I.A.U. 1, 35, 1922) and by the International Committee on Weights and Measures (Procès-Verbaux Comité Int. Poids et Mesures (2), 12,67,1927). Specifications for the production of this primary standard were adopted provisionally by the I.A.U. in 1925 (Trans. I.A.U. 2, 47, 232, 1925), and by the I.C.W.M. in 1927 (Procès-Verbaux Comité Int. Poids et Mesures (2), 12, 67, 1927). Three reports of this Commission (Trans. I.A.U. 3, 77, 236, 1928; ibid. 4, 58, 233,1932; ibid. 5, 81, 299, 1935) have discussed the divergences in these specifications and pointed out the unsatisfactory features of each. This discussion culminated in a revised specification (Trans. I.A.U. 5, 303, 1935) which was adopted unanimously by the I.C.W.M. in 1935 (Procès-Verbaux Comité Int. (2), 17, 91,1935).
29. Commission des Spectres Stellaires
Authors: Russell M. H. N. , Adams MM. W. S. , Beals  , Cannon Mile , Cecchini MM. , Chalonge  , Colacevich  , Gaposchkin Mme Payne , Gerasimovich MM. , Joy  , Kohlschütter A. , Lindblad  , Merrill  , Milne  , Morgan W. W. , Plaskett H. H. , Plaskett J. S. , Redman  , Stratton  , Struve  , Swings  , Wright W. H.
Published: July 2016

Two-thirds of the members of the Commission have replied to the request of the chairman for an expression of their opinion. Most of them are in general well satisfied with the existing system of classification and nomenclature. Lindblad reports on successful work upon the determination of absolute magnitudes of faint stars, in many ways. Adams writes: “I might suggest that attention be called in the report to the fact that the ultra-violet spectra, even of stars like β Orionis, show large numbers of lines. As you probably remember, the spectrum of Sirius resembles, at first sight, the solar spectrum. If all observatories had the facilities for getting spectra in the far ultra-violet, this region would probably furnish the best criteria for spectral type.” Merrill suggests: “The nomenclature which, upon the basis of atomic transition, assigns the adjective ‘nebular’ to lines which may not occur in nebulae, and ‘ auroral ‘ to lines which may not occur in the aurora, is surely not an ideal one.
30. Commission des Vitesses Radiales Stellaires
Authors: Adams M. W. S. , Bok MM. , Guthnick  , Harper  , Joy  , Knox-Shaw  , McLaughlin  , Merrill  , Mohr J. M. , Moore J. H. , Neubauer  , Pearce  , Plaskett J. S. , Sanford  , Shajn G. , Shapley  , Struve  , Young R. K.
Published: July 2016

During the past three years the measurement of stellar radial velocities has formed an important part of the spectroscopic programme of most observatories possessing large telescopes. As observations are carried to fainter and fainter stars and the number of observable objects increases rapidly, a natural development has been the selection of special groups and types of stars, the radial velocities of which will aid in the solution of certain specific problems. Illustrations are the studies of the O, B and A type stars made at the Dominion Astrophysical, the Lick, and the Simeis Observatories, of the members of the galactic clusters at the Lick Observatory, and of the fainter Cepheid variables and early-type stars with strong interstellar lines at the Mount Wilson Observatory.
Conseil International des Unions Scientifiques
Authors: Fabry Ch. , Kruyt H.R. , Stratton F. J. M.
Published: July 2016

1 . Le Conseil International a pour but:

(a)

D’établir des liaisons d’une part entre les organisations nationales adhérentes, et d’autre part entre les diverses Unions intemationales;

(b)

D’orienter l’activité scientifique internationale dans les domaines où il n’existe pas d’associations compétentes;

(c)

D’entrer, par l’intermédiaire des organisations nationales adhérentes, en relation avec les Gouvernements des pays adhérents pour recommander des mesures favorables au développement scientifique de ces pays.
7. Celestial Mechanics
Authors: Eckert W. J. , Duboshin G. N. , Chebotarev G. A. , Hagihara Y. , Kovalevsky J. , Kozai Y. , Message P. J. , Stumpff K. , Szebehely V. G. , Zagar F.
Published: July 2016

The most exciting feature of contemporary celestial mechanics is the close interaction with three of the most dramatic engineering achievements of our time: the electronic computer, artificial celestial objects, and the precise measurement of distances in the solar system. The last two provide new information for and make new demands on celestial mechanics and the former provides an effective means of response. These developments have also stimulated people with backgrounds other than celestial mechanics to make contributions in the field.

Since the last meeting of the Union, the use of the computer for literal theoretical developments has become effective and widespread.

The creation of artificial celestial objects not only requires the services of celestial mechanics but provides the means of obtaining new measurements that may throw light on the physical laws that govern the motion of celestial objects. In other words, we can now perform experiments as well as observe.
30. Radial Velocities
Authors: Evans David S. , Abt H. A. , Batten A. H. , Blaauw A. , Bouige R. , Thackeray A. D.
Published: July 2016

Les mesures de vitesse radiale (VR) ont été continuées par les trois techniques: prisme objectif, spectrographie à fente, interférométrie, avec des instruments en fonction à l’Observatoire de Haute Provence ainsi qu’à celui de l’ESO.

Grand Nuage de Magellan: Le travail de 13 champs est pratiquement achevé et sera publié dès que les mesures de spectres de fente pris au Chili seront complètement dépouillés.

Un catalogue comprenant 1765 étoiles galactiques et 469 étoiles du Grand Nuage de Magellan est achevé. Un supplément comprend environ 200 étoiles particulières de cette région.
12 Radiation and Structure of the Solar Atmosphere
Authors: Uchida Yutaka
Published: July 2016

The report of Commission 12 presented here covers the parts of the field of solar physics other than those directly related to solar activities which, in our view, are the time-dependent phenomena inherent to solar active regions to be covered by Commission 10. From the sub-fields in the domain of Commission 12, the Organizing Committee selected six topics of special interest and invite six researchers to prepare reviews. Topics selected and reviewers are (1) Variations of Total Solar Irradiance ( Dr. R. C. Willson, Jet Propulsion Laboratory ), (2) Solar Global Oscillations ( Dr. E. Fossat, University of Nice ), (3) Magnetic Activity and Rotation in the Sun and Stars ( Dr. R. W. Noyes, Harvard University ), (4) Photospheric Magnetic Concentration and Related Problems ( Dr. H. C. Spruit, Max Planck Institut fur Astrophysik ), (5) Coronal Loop Structure and its Heating ( Dr. E. Priest , University of St. Andrews ), and (6) Coronal Transients ( Dr. E. Hildner, NASA Marshall Space Flight Center ). Of course it is not that there were no important contributions to the progress of sub-fields of solar physics other than those presented here. It was our consensus, however, that we should adopt this method since a complete coverage of works appearing across the entire field is no longer possible because of the rapid increase in the number of works in the expanding field of solar physics when severe page limitations exist for the IAU Reports.
Report of the IAU Working Group on ICRS
Authors: Mignard F.
Published: July 2016

After the adoption of the ICRS and its primary materialization by the ICRF in January 1998, the last three years have witnessed a burst of interest in stellar astrometry stimulated by the availability of the ICRF and its optical counterpart. This paper reports on the activities carried out by the members of the IAU appointed working group on reference frames as well on other works directly related to the main goals of this working group.
Determination of Optical Positions for Extragalactic Radio Sources under the Collaboration Between SHAO and NAO
Authors: Tang Z.H. , Jin W.J. , Wang S.H. , Pinigin G. , Shulga A. , Maigurova N. , Protsyuk Yu.
Published: July 2016

The optical positions of 9 compact extragalactic radio sources have been determined by using the 1.56m, 1m and 60/90cm telescopes with CCDs in China and the Axial Meridian Circle at Nikolaev Astronomical Observatory since Jan. 1996 in a cooperative project between the two observatories. The instrumentation, observations and reduction are briefly described, and the preliminary results are presented. The comparison between the optical and radio positions for 9 sources are also given. More optical positions of radio sources are being processed.
Dynamical Reference Frame — Current Relevance and Future Prospects
Authors: Standish E.M.
Published: July 2016

Planetary and lunar ephemerides are no longer used for the determination of inertial space. Instead, the new fundamental reference frame, the ICRF, is inherently less susceptible to extraneous, non-inertial rotations than would be a dynamical reference frame determined by the ephemerides. Consequently, the ephemerides are now adjusted onto the ICRF, and they are fit to two modern, accurate observational data types: ranging (radar, lunar laser, spacecraft) and VLBI (of spacecraft near planets).

The uncertainties remaining in the inner planet ephemerides are on the order of 1 kilometer, both in relative positions between the bodies and in the orientation of the inner system as a whole. The predictive capabilities of the inner planet ephemerides are limited by the uncertainties in the masses of many asteroids. For this reason, future improvements to the ephemerides must await determinations of many asteroid masses. Until then, it will be necessary to constantly update the ephemerides with a continuous supply of observational data.
Definition of the Celestial Ephemeris Pole and the Celestial Ephemeris Origin
Authors: Capitaine Nicole
Published: July 2016

The adoption of the International Celestial Reference System (ICRS) by the IAU in use since 1 January 1998, and the accuracy achieved by the most recent models and observations of Earth rotation call for a redefinition of the Earth Orientation Parameters (EOP). First, the precession-nutation parameters and Greenwich sidereal time, which are currently defined in the FK5 System, have to be re-defined to be consistent with the ICRS. Second, the current definition of the Celestial Ephemeris Pole (CEP) has to be extended in order to be consistent with the most recent models for nutation and polar motion at a microarsecond accuracy including diurnal and sub-diurnal components, as well as with new strategies of observations. Such issues have been under consideration by the subgroup T5 named “Computational Consequences” of the IAU Working Group “ICRS”. This paper gives, as the basis for future recommendations, the preliminary proposals of the subgroup T5 for a modern definition of the CEP, for the definition of more basic EOP in the ICRS and for the choice of a new origin on the equator of the CEP in place of the equinox. Then, the paper emphasizes the use of the Celestial Ephemeris Origin (CEO) which is defined as the “non-rotating origin” in the celestial frame on the equator of the CEP.
Improved Models for Precession and Nutation
Authors: Mathews P.M.
Published: July 2016

The modeling of nutations and precession has advanced to the point where the rms of residuals between theory and the observational estimates from the VLBI data of the past decade is only 0.16 mas in Δψ sin є0 as well as in Δє. Such a fit is provided by the MHB2000 nutation series (Mathews et al., 2000) based on geophysical theory with a few basic Earth parameters estimated by a fit to nutation-precession data, and its accompanying precession rate. A brief account of the series is presented, along with an outline of the theoretical background and of the geophysical information of interest obtained in the process of constructing the series. A series due to Shirai and Fukushima (2000) also gives a somewhat comparable fit to data, improving on the IERS 1996 series, but it is essentially empirical and provides no geophysical insights.
Precession-Nutation Estimates from Optical Astrometry 1899.7–1992.0 and Comparison with VLBI Results
Authors: Vondrák Jan , Ron Cyril
Published: July 2016

The most recent solution of Earth orientation parameters from the observations made by optical astrometry in 1899.7-1992.0 at 33 observatories is used to estimate the corrections of the present IAU model of precession-nutation. Since the resolution of the solution is about five days, only the terms with periods of 14 days and longer are considered. The results are compared with VLBI-based corrections of the standard precession-nutation model, and the differences are discussed.
Sub-Microarcsecond Astrometry and New Horizons in Relativistic Gravitational Physics
Authors: Kopeikin Sergei M. , Gwinn Carl R.
Published: July 2016

Attaining the limit of sub-microarcsecond optical resolution will completely revolutionize fundamental astrometry by merging it with relativistic gravitational physics. Beyond the sub-microarcsecond threshold, one will meet in the sky a new population of physical phenomena caused by primordial gravitational waves from the early universe and/or different localized astronomical sources, space-time topological defects, moving gravitational lenses, time variability of gravitational fields of the solar system and binary stars, and many others. Adequate physical interpretation of these yet undetectable sub-microarcsecond phenomena cannot be achieved on the ground of the “standard” post-Newtonian approach (PNA), which is valid only in the near-zone of astronomical objects having a time-dependent gravitational field. We describe a new, post-Minkowskian relativistic approach for modeling astrometric observations having sub-microarcsecond precision and briefly discuss the light-propagation effects caused by gravitational waves and other phenomena related to time-dependent gravitational fields. The domain of applicability of the PNA in relativistic space astrometry is outlined explicitly.
Numerical Data-Processing Simulations of Microarcsecond Classical and Relativistic Effects in Space Astrometry
Authors: Kopeikin Sergei M. , Shuygina N.V. , Vasilyev M.V. , Yagudina E.I. , Yagudin L.I.
Published: July 2016

The accuracy of astrometric observations conducted via a space-borne optical interferometer orbiting the Earth is expected to approach a few microarcseconds. Data processing of such extremely high-precision measurements requires access to a rigorous relativistic model of light ray propagation developed in the framework of General Relativity. The data-processing of the space interferometric observations must rely upon the theory of general-relativistic transformations between the spacecraft, geocentric, and solar barycentric reference systems allowing unique and unambiguous interpretation of the stellar aberration and parallax effects. On the other hand, the algorithm must also include physically adequate treatment of the relativistic effect of light deflection caused by the spherically-symmetric (monopole-dependent) part of the gravitational field of the Sun and planets as well as the quadrupole- and spin-dependent counterparts of it. In some particular cases the gravitomagnetic field induced by the translational motion of the Sun and planets should be also taken into account for unambigious prediction of the light-ray deflection angle. In the present paper we describe the corresponding software program to take into account all classical (proper motion, parallax, etc.) and relativistic (aberration, deflection of light) effects up to the microarcsecond threshold and demonstrate, using numerical simulations, how observations of stars and/or quasars conducted on board a space optical interferometer orbiting the Earth can be processed and disentangled. For numerical simulations the spacecraft orbital parameters and the telescope optical-system-characteristics have been taken to be similar to those in the Hipparcos mission. The performed numerical data analysis verifies that the relativistic algorithm chosen for data processing is convergent and can be used in practice to determine astronomical coordinates and proper motions of stars (quasars) with the required microarcsecond precision. Results shown in the paper have been obtained with a rather small number of stars (a few thousand). Simulations based on a much larger number of stars, e.g., from the Guide Star Catalogue used to model original observations will give more complete information about potential abilities of the space astrometric missions.
Pulsar Scintillation: Overview and Some Recent Results
Authors: Gupta Yashwant
Published: July 2016

Radio signals from pulsars are significantly affected by scattering in the interstellar medium. A review of this phenomenon of pulsar scintillation forms the main objective of this paper. The basic concepts are described and some new results related to the following aspects are presented: (i) understanding of refractive scintillation effects and (ii) constraining the spectrum of electron density fluctuations in the interstellar medium.
Frequency Structure of Radio Scintillations for Several Pulsars
Authors: Kondratiev V.I. , Popov M.V. , Soglasnov V.A. , Kostyuk S.V.
Published: July 2016

Scintillation times and decorrelation bandwidths for the pulsars B0329+54, B1641-15, B1508+55 and B1919+21 are determined. The results are based on observations made with different instruments and at different radio frequencies. All objects but the pulsar B1508+55 were detected to have more than one frequency scale. The obtained values of scattering parameters are not contrary in general to the Kkolmogorov form of density fluctuation spectrum.
Scintillation Observations of Strong Northern Pulsars
Authors: Wang Na , Manchester R.N. , Yusup Aili , Wu Xinji , Zhang Jin , Chen Maozheng
Published: July 2016

Scintillation of pulsar radio emission provides information about the interstellar medium along the path to the pulsar and the velocities of pulsars. It also affects the precision of pulse timing observations. Using a pulsar timing system developed at the Urumqi Astronomical Observatory 25 m telescope, we observed diffractive scintillation dynamic spectra for several strong northern pulsars. This paper introduces the observing system and discusses the observational results.
Pulsar Investigation Using Interstellar Scintillation
Authors: Smirnova T.V. , Shishov V.I.
Published: July 2016

We discuss the resolution of pulsar magnetospheres using interstellar scintillation. The two-dimensional spatial structure of pulsar emission zones can be obtained from analysis of diffractive scintillations at low frequencies. Based on refractive and diffractive scintillation of pulsars we can also reconstruct the distribution of turbulent plasma along the line of sight, and using this analysis a new approach to pulsar distance estimation can be made.
VSOP Observations of the BL Lac Object 2007+777
Authors: Jin C. , Krichbaum T.P. , Witzel A. , Nan R. , Peng B. , Kraus A. , Lobanov A. , Qian S. , Zensus J.A.
Published: July 2016

We present three epochs of VSOP observations of the BL Lac object 2007+777 at 5 GHz. Compared with the ground-based VLBA data, the space baselines with HALCA clearly reveal a more detailed and finer source structure. Mainly based on the quite uniform and circular UV-coverages of the VLBA, and using a new cross-selfcalibration method, we have found evidence for weak structural changes on a timescale of two weeks in the core region of this intraday variable source. The physical causes for these variations are discussed.
Interpretation of Extreme Scattering Events
Authors: Walker Mark A.
Published: July 2016

Extreme Scattering Events are sometimes manifest in the light-curves of compact radio-quasars at frequencies of a few GHz. These events are not understood. The model which appears to offer the best explanation requires a new population of AU-sized, neutral gas clouds; these clouds would then make up a large fraction of the Galaxy’s dark matter. Independent of the question of which theoretical model is correct, if we extrapolate the observed behaviour to low radio-frequencies, we expect that the sky should be criss-crossed by a network of narrow caustics, at frequencies below about 700 MHz. Consequently at these frequencies sources should typically manifest additional, faint images which are substantially delayed with respect to the primary image. Although some examples of this type of behaviour are already known, it is expected that these are just the tip of the iceberg, with strong selection biases having been imposed by the instrumentation employed to date.
Magnetic Fields in our Galaxy: How much do we Know? I. Disk fields within a few kpc of the Sun
Authors: Han J.L.
Published: July 2016

The large scale magnetic fields of our Galaxy have been mostly revealed by rotation measures (RMs) of pulsars and extragalactic radio sources. In the disk of our Galaxy, the average field strength over a few kpc scale is about 1.8 μG, while the total field, including the random fields on smaller scales, has a strength of about 5 μG. The local regular field, if it is part of the large scale field of a bisymmetric form, has a pitch angle of about −8°. There are at least three, and perhaps five, field reversals from the Norma arm to the outer skirt of our Galaxy.
Active Adaptive Arrays: The Astron Approach to SKA
Authors: Strom Richard G. , Smolders Bart , van Ardenne Arnold
Published: July 2016

It has been argued, for a number of reasons, that the next generation radio telescope should be a multi-element interferometer with a collecting area of about 1 km2. The remaining parameters of such an instrument – frequency range, angular resolution, instantaneous bandwidth, etc. – will be science driven. The requirements for propagation studies are briefly discussed, and it is pointed out how variable-source confusion may differ from the normal variety. Finally, the Dutch project to achieve a large collecting area using adaptive arrays of active antennas is described. A systematic approach has been adopted, with the construction of arrays of increasing complexity to test design features at each state. Recently, development of a low frequency array (LOFAR) has become an additional option. It would facilitate tests of some of the larger instrument’s features, and provide real data on the influence of the ionosphere and interfering sources.
Spectroscopic Spin Variability in new IP Candidates
Authors: de Martino Domitilla , Haberl Frank , Alcalá Juan M. , Grado Aniello
Published: July 2016

We present fast spectroscopy of RX J1548-45 and BT Mon acquired with EFOSC-ESO 3.6 m in March & April 2002, with the aim to detect for the first time spectral variability at the white dwarf rotation.
Stream Eclipse Mapping with ‘Fire-Flies’
Authors: Bridge C. M. , Hakala Pasi , Cropper Mark , Ramsay Gavin
Published: July 2016

We apply a new method of eclipse mapping to the light curves of eclipsing polars. The technique aims to locate the bright emission associated with the accretion stream, using a technique that makes the fewest prior assumptions about the location of the accretion stream material. We have obtained data of EP Dra and HU Aqr with the S-Cam 2 superconducting tunnel junction camera using the William Herschel Telescope. The location of emission regions in both systems show that previously assumed trajectories are consistent with those found using our technique. Most of the emission is located in a region where we expect material to be confined to magnetic field lines, particularly for HU Aqr, while there appears to be a lack of emission from where we conventionally expect material to follow a ballistic trajectory from the L1 point.
Can the propeller outflow from AE Aquarii be imaged directly?
Authors: Still Martin , Horne Keith , Knigge Christian
Published: July 2016

We calculate the Hα luminosity of an outflow nebula resulting from propeller action in AE Aqr. While the outflow is bright enough to be detected as an extended source, 1 arcsec across, it is dominated by the point-spread function (PSF) wings of the central object. By subtracting a PSF model from HST PC data we rule out the extreme models of high mass-loss rate combined with narrow-angle outflow, but more precise measurements are required to explore the propeller parameter space further.
Earth Rotation Information Derived from Merit and Polaris VLBI Observations
Authors: Robertson D. S. , Carter W. E.
Published: July 2016

In September and October 1980, the National Geodetic Survey, jointly with the National Aeronautics and Space Administration and several other agencies and institutions, conducted a series of astronomical radio interferometry (VLBI) observing sessions to support the IAU/IUGG MERIT short campaign. A total of 14 days of observations, organized into two 7-day sessions, was collected by three observatories in the United States (Harvard Radio Astronomy Station (HRAS), Haystack Observatory, and Owens Valley Radio Observatory) and the Onsala Space Observatory in Sweden. Chilbolton Observatory, England, and Effelsberg Observatory, West Germany, also participated on some days. Immediately following the MERIT campaign, NGS initiated a series of 24-hour observing sessions, spaced at approximately 2-week intervals, as a pilot program to project POLARIS. All of these sessions included two observatories, HRAS and Haystack, and Onsala participated in about half of the sessions. The MERIT and POLARIS observations were made with the third generation MARK III VLBI system using procedures and schedules designed to yield high quality geodetic information, including Earth rotation values. This paper briefly traces the planning, observing, and data processing activities, and presents the Earth rotation information thus far derived from the data.