Astronomiske observationer: observatorier, udstyr og metoder

For anyone artistically inclined, observing the Moon and attempting to sketch or paint it can easily become a passion. The Moon presents a broad array of tone, texture, and form. Capturing this in a painting or sketch at the eyepiece of a telescope - or even with binoculars - develops observational skills, leaves a record of the observation, and can also be a delightful and rewarding pastime. However, the choice of media available is extensive (acrylic paint, oils, pen, charcoal, etc., and even computer art programs), and there is no existing text that fully explains all lunar sketching and painting techniques in each respective medium. This beautiful and graphically rich book fulfills this requirement. It presents detailed step-by-step instructions, in the form of illustrated tutorials for every major medium employed to represent the Moon. It also provides practical advice on how to sketch outdoors at night (not ideal conditions for an artist!). This is easily the most extensive book on the subject of lunar art for amateur astronomers, particularly those observing through a telescope. The diverse features of the lunar surface will attract and entice readers to review the number of different media presented, exciting and inspiring them with the possibilities of learning to depict all of the fascinating aspects of Earth's very own satellite.

The Casual Sky Observer's Pocket Guide offers an observing program for occasional amateur observers looking for some quick, fun astronomy adventures under the stars. In the real world, where time for observing is limited, the weather is seldom perfect, and expensive equipment is not an option, amateur astronomy may not be seen as a worthwhile activity. However, portable and quick-to-set-up instruments are available. A pair of binoculars or a small telescope fills the bill. And the way to make the most of these instruments is described in the Casual Sky Observer's Pocket Guide. Not only does the book feature the best and brightest showpieces of the heavens; it also provides a great deal of physical and environmental data as well as lots of fascinating information and beautiful illustrations that provide a unique perspective on the many treasures within and beyond our home galaxy, the Milky Way--stars, star clusters, other galaxies, and nebulae, all within reach of binoculars or a small telescope.

Proceedings of the 129th Symposium of the International Astronomical Union, held in Cambridge, MA, USA, May 10-15, 1987

The objective of this meeting was to bring together collea­ gues from different branches of observational astronomy and theoretical astrophysics to discuss and analyse the rapid progress in our knowledge and understanding of the matter surrounding stars, streaming off stellar surfaces, or fall­ ing onto stars. The meeting was sponsored by IAU Commis­ sions 36 (Theory of Stellar Atmospheres), 29 (Stellar Spec­ tra), and 34 (Interstellar Matter). There were two special reasons for organizing this meeting at Heidelberg in 1986: During this year the University of Heidelberg celebrated its 600th anniversary and the IAU symposium joined the many scientific events accompanying this celebration. Secondly, the year 1986 also marked the conclusion of a special co­ operative research project ("Sonderforschungsbereich") in astrophysics at Heidelberg, a major part of which had been devoted to the physics of circumstellar matter. The main topics discussed at this meeting were: (1) circumstellar matter, bipolar flows, and jets from young stars and protostars; (2) circumstellar envelopes of evolved stars; (3) stellar coronae; (4) stellar winds from hot and cool stars; (5) dust formation and circumstellar chemistry. Many exciting new results were presented in 21 invited or review papers, 26 contributed papers, and 127 poster papers. This symposium would not have been possible without the generous financial assistance of the International Astronomical Union, the German Science Foundation (DFG), and the State Government of Baden-Wurttemberg. The practi­ cal support of the University of Heidelberq and the Max­ Planck-Society was also very valuable.

Ken Freeman I would like to pick out a few items that I found particularly interesting. The choice probably reflects my ignorance, because many of these topics are no doubt more known to most of you. I am fairly sure that some of them are basic and important. We will start with the first session. There were three closely related papers on the evolution of massive stars, the formation of open clusters and associations and the IMF. We learned that clusters appear to form in initially bound clouds 6 of masses between 10'+_10 M , but star formation is a destructive process. Most of the gas is@ lost and the remaining stars then find themselves in an unbound system, which naturally disperses on a dynamical time. As a result of this, star formation is typically a fairly inefficient process, at least on the scale of open clusters. However (as Heggie pointed out) it seems to be somewhat more efficient on smaller scales, as evidenced by the fairly high incidence of binary stars. To form a bound cluster requires a higher efficiency of star formation, typically 30% or more, and we see how the three papers of this morning session relate: the initial mass function and the timing of where and when the DB stars form dictate the likely fate of the system.

The XVlllth General Assembly of the International Astronomical Union was held in Patras, Greece, from 17-26 August 1982. It was marked by the tragic death of the President of the IAU, Professor M.K.V. Bappu, on August 19, 1982. This sad event, without precedent in the history of the Union, posed serious problems to the organization of the General Assembly, which could only be overcome by the full collaboration of all members, the organizers, and the Executive Committee. A tribute to the memory of Prof. Bappu was paid during a plenary meeting on 23 August 1982. The full texts of the speeches are published in Chapter I of this . volume. The excellent scientific programme in Patras was organized by the Presidents of the 40 IAU Commissions and coordinated by the IAU General Secretary (1979-1982), Professor P.A. Wayman. The local arrangements were taken care of by Professor C. Goudas and his collaborators from the Patras University. Due to the unexpected withdrawal in 1979 of another invitation to host the 1982 IAU General Assembly, the organizers in Greece had less than two years available for the extensive preparations, and our hearty thanks are due to them for their persistent efforts, which made this General Assembly an outstanding success.

The lAU Symposium No. 78, "Nutation and the Earth's Rotation," was held in Y~ev, USSR, from 23 to 28 May, 1977. The Organizing Committee included E. P. Fedorov and R. O. Vicente (Joint Chairmen), W. Fricke, J. Kovalevsky, P. Melchior, N. Pariisky, M. Rochester, C. Sugawa, G. Wilkins and Ya. Yatskiv, who presided over the Local Organizing Com­ mittee. The meeting was sponsored by Commission 19 and co-sponsored by Commissions 4, 8, and 31. There were 114 registered participants from 14 countries. The main topics covered were as follows: the specification of nutation in the lAU system of astronomical constants; determination of forced nutation and nearly diurnal free polar motion from astronomical observations; expected use of lunar ranging data and long baseline interferometers for precise measurement of the nutation terms; models of the internal constitution of the Earth as the basis of a new theory of nutation; the effect of the ocean and liquid core on the rotation of the Earth; and the interaction between Earth tides and nutation.

IAU Transactions XXIIB summarizes the work of the XXIInd General Assembly. The discourses given during the Inaugural and Closing Ceremonies are reproduced in Chapters I and III, respectively. The proceedings of the two sessions of the General Assembly will be found in Chapter II, which includes the Resolutions and the report of the Finance Committee. The Statutes, Bye-Laws and a few working rules of the Union are published in Chapter IV. The Accounts and other aspects of the administration of the Union are recorded in Chapter V, together with the report of the Executive Committee for this last triennium, and provide the permanent record for the Union in the period 1991-1994. This volume also contains the Commission reports from The Hague compiled by the Presidents of the Commissions (Chapter VI). Finally, Chapter VII contains the list of countries adhering to the Union and the alphabetical, geographical and commission membership lists of about 8000 individual members. The IAU still appears to be unique among the scientific Unions in maintaining this category of individual membership which contributes in a crucial way to the spirit and the aims of the Union.

This volume of the Highlights of Astronomy contains the Invited Discourses and the proceedings or summaries of Joint Discussions, Special Sessions, and Working Group Meetings held at the XIInd IAU General Assembly in August 1994 in The Hague. While the three Invited Discourses are reproduced in the order of their appearance in the meeting programme, the Joint Discussions have been reordered according to their topics. Not included in this volume are the proceedings of the GA Symposia which will be published individually in the IAU Symposia series. I am most grateful to the authors of the invited discourses for preparing manuscripts in spite of heavy other commitments. It is a pleasure to express my appreciation of the work by Dr. Jacqueline Bergeron in organizing the XXIInd General Assembly, and I wish to thank all authors and meeting chairpersons for their cooperation and for providing their contributions in time to meet the customary publication schedule of this series. Special thanks are due to Ms. Monique Leger-Orine from the IAU office for considerable and patient assistance in the final editing, and to Dr. Tom Herbst from the Max­ Planck-Institute for Astronomy for permission to reproduce on the cover of this volume one of his IR images of Jupiter obtained just after the Comet Shoemaker-Levy 9 impact, one of the definite Highlights of Astronomy in 1994.

G. MICHAUD Dipartement de Physique Universiti de Montrial c. P. 6128, succursale A Montrial, Que. , H3C 317 Canada The aim of IAU Symposium 145 was to use the photospheric abundances of the chemical elements to give us some hint of the past evolution and of the current structure of stars. At the invitation on the Bulgarian Academy o/Sciences, it brought together one hundred and fifty one scientists from 21 countries to 71atni Pjasaci (Golden Sands), Bulgaria, for a five day meeting. The processes discussed included accretion, mass loss, mass exchange, convection, turbulence, meridional circulation, and diffusion in addition to nuclear reactions. Observationally, spectroscopy was involved. New telescopes and instruments have considerably extended the scope of spectroscopy over the last few years. Space telescopes, such as IUE, have allowed the development of far UV spectroscopy. The access to the infrared has proven critical for probing cool stars. Large ground based telescopes have allowed fainter objects to be observed especially when they are equipped with more efficient detectors such as CCDs and Reticons. The co-adding of digitalized photographic plates has extended their usefulness. It has become possible to make high resolution, high signal to noise observations of objects that could only be observed at low resolution in former days. Weak lines can now be measured with accuracy, allowing the precise determination of the abundances of elements as rare as lithium and the determination of precise limits to isotopic ratios.