The restructuring of our commission, adopted at the last General Assembly, was undoubtedly beneficial and various activities were developed under the aegis of the commission.

Two very important changes have marked the last triennium: the World Wide Web and electronic publishing. The American Astronomical Society is the first to have introduced an electronic version of an astronomical journal and will be followed soon by the Astronomy and Astrophysics Journal. Last February, an ICSU/UNESCO Conference was held in Paris on this topic. A.G. Hearn was the IAU representative. An extensive report of this meeting can also be found on the Web (http://astro.fys.ruu.nl:8000/iau) and the proceedings are available also on the Web (http://www.lmcp.jussieu.fr/icsu/Information/index.html. A Joint Discussion on this very hot topic will be held during the Kyoto General Assembly.

As a result of the deliberations and discussions during the last General Assembly of the IAU in The Hague, it was recommended that Commission 14 become a commission of the Executive Committee. The special interdisciplinary role and nature of Comm. 14 were in this way recognized and encouraged.

Education is important to astronomers because it affects the recruitment and training of future astronomers, and because it affects the awareness, understanding, and appreciation of astronomy by taxpayers and politicians.

There are many other reasons why astronomy should be part of education and culture. Astronomy is deeply rooted in the history of almost every society, as a result of its practical applications and its philosophical implications. It still has everyday applications to calendars and timekeeping, navigation, seasons and climate. It has longer-term applications to climate change and biological extinctions. Astronomy advances the other sciences, and is a dynamic science in its own right. It deals with our place in time and space, our cosmic roots, and our kinship with other peoples and species on earth. It reveals a universe which is vast, varied, and beautiful, and it promotes curiosity, imagination, and a sense of shared exploration and discovery. It provides an enjoyable hobby for millions of people. In a school context, it provides an alternative approach to the scientific method - the observational (as opposed to experimental) approach. It can attract young people to study science and technology. It can promote rational thinking, and it can increase public interest in science and technology. These benefits are important in all countries, both developed and developing.

During the past triennium many efforts have been made by individual members and Commission 50 to keep a good observational environment, along the lines set up by the previous Commission 50 president, P. Murdin. The number of commission members is 65, which is unchanged from the previous period. Since our problems become more severe year by year and are connected directly to the activities of all observational astronomers and indirectly to those of all theoreticians, the commission should have made an effort to increase the number of active members.

The book “Adverse Environmental Impact on Astronomy” edited by D. McNally was published by Cambridge University Press in 1994. This book is a direct output of a meeting held by UNESCO, ICSU and IAU at the headquarters of UNESCO in Paris from June 30 to July 2 in 1992, and shows nearly all the problems which we are facing.

The Antarctic plateau provides the best site conditions on the Earth for a wide range of astronomical observations, both of photons and particles. This is a result of the unique combination of cold, dry and tenuous air found only there. Wintertime temperatures average below -60˚C, with minimal diurnal variation, the precipitable water vapour content is below 250 μm, the katabatic wind is low on top of the plateau and there are no jet streams at high altitude. The vast quantities of pure ice can be used as an absorber for particle detectors. Secondary benefits include continuous viewing for any source visible, lack of pollution and dust in the atmosphere, and low electromagnetic interference. Considerable activity is now focussed at the South Pole on developing facilities for astronomy. Initial investigations of higher sites have begun, particularly at Dome C.

Since the 22nd IAU General Assembly in the Hague in 1994, WGPSN has conducted most of its business by e-mail and fax. Ad hoc WG meetings were held on July 10, 1996 in Versailles and on July 17 in Birmingham during, respectively, the Asteroids, Comets and Meteors meeting and the 31st COSPAR Scientific Assembly. Seven members of the WG and two members of the adhering Nomenclature Task Groups attended one of the nomenclature meetings or both.

During the past triennium some effort has been put into setting up what we hope will be an effective Working Group which currently has the above composition. Membership includes the Presidents of Commissions 38 and 46 ex-officio, so some regular change is built in every three years, as these Presidents change. Thanks are due to R. Kippenhahn, P. Lena, and J. Sahade, members of the original Working Group, who have retired from its active membership. The Chairman retains an extensive mailing list of about some 100 names. All those on that list will continue to receive the WG Newsletter. The present system is to mail one Newsletter annually, in April. At the time of writing, two such mailings have been made since the last General Assembly.

The idea for a Working Group (WG) on “Future Large Scale Facilities in Astronomy” grew from a discussion held on 20 August, 1994, during the IAU General Assembly in The Hague. The IAU Executive Committee approved its formation in August, 1995, and its composition in October, 1995. The WG will remain active at least until the XXIIIrd General Assembly in Kyoto in 1997. Members are: H. Butcher (Chairman), R. Ekers, B. Fort, N. Kardashev, M. Longair, F. Pacini, L. Rodriguez, G. Swarup, Y. Tanaka, H. Tananbaun, and L. Woltjer (ex officio). The WG carries out its work mostly by email and FAX.

The two years that elapsed since the establishment of Division 1 have been characterised by a large variety of tasks of common interest to the five Commissions forming the Division. This is shown in particular by the activity of the Working Groups on Astronomical Standards (Chairman, T. Fukushima) and on Reference Frames (Chairman, L.V. Morrison) which include members from the five Commisions and were actually Division 1 Working Groups. This is also reflected by the very close relationship that prevailed between Commissions 8 and 24. They actually are preparing an eventual merging between the two commissions by proposing that both commissions have the same Vice-President for the next term (E. Schilbach). Last, but not least, three of the Joint discussions accepted for the Kyoto General Assembly are sponsored by the whole Division, one of its Commissions being the proposer. However, these common actions are only a small fraction of the activity of each Commission as described in their reports.

During 1994-1996 Ephemerides have been intensively developed for all celestial bodies in the solar system in both analytical and numerical ways, except an analytical ephemeris of Pluto. Because of the shortage of allotted pages this report covers only the reviews of planetary ephemerides. Ephemerides of natural satellites and other bodies will be included in the next report as six years' achievements. Conventional reports from institutions and individual members were published in the Newsletter of Commission 4.

In preparing this report the reviews by M. Standish and P. Bretagnon are highly appreciated.

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.

Spatial structures in the solar photosphere are likely to be seen down to scales of the order of the photon mean free path, which is about 70 km in the lower photosphere. This scale corresponds to an angle of O.”1 at disk center. Structures associated with magnetic fields may be expected on even smaller scales. Existing solar telescopes typically have diameters of slightly less than one meter. Hence, even in the visible part of the spectrum, the scales of solar structures extend out to the diffraction limit of current solar telescopes. Therefore, the achievable spatial resolution is limited by turbulence in the Earth’s atmosphere (seeing). This has led to the development of various techniques to overcome this resolution limit and achieve diffraction-limited resolution. This report covers selected highlights and recent work done in the context of high-resolution techniques published in the period from July 1, 1993 to June 30, 1996. Due to the lack of space the report remains necessarily incomplete, and I apologize to all the authors of important contributions that are not cited here. This review does not cover space and balloon-borne instruments that try to achieve high spatial resolution by observing from above the Earth’s atmosphere. Recent work on ground-based high-resolution techniques has been collected in the proceedings of the 13th Sacramento Peak Summer Workshop on Real Time and Post Facto Solar Image Correction (Radick 1993).

Solar wind ion composition measurements are a unique tool to investigate solar system processes, ranging from the solar interior out to the heliospheric boundary. Compositional changes in the solar wind, which originates in the outer convective zone (OCZ) of the Sun, are produced in the transport of solar matter from the OCZ to the solar corona and in the process of lifting the coronal plasma out of the solar gravitational field up to the termination shock and beyond. During the last three years instrumentation originally designed to measure the composition of the solar wind has detected further pick-up ion species in the solar wind and thereby strongly motivated pick-up ion related research. This review therefore puts particular emphasis on pick-up ion observations and their theoretical interpretation.

This report has, following the usual practice in Commission 15, been compiled primarily by the chairpersons of the two working groups. E. Tedesco prepared the entire section about Asteroids and Meteorites. H. U. Keller prepared the section about Comets using material originally prepared by E. Kiihrt (nuclei), H. Bohnhardt (dust), R. Schulz (neutral gas), and W.-H. Ip (plasma). M. F. A’Hearn did minor editing to merge the two reports and fit the report into the allotted space.