The last triennium, and coincidentally the last few years of the 20th century, has been a most remarkable time for Commission 9, and for astronomy in general. Ground-based astronomy in particular has received an enormous boost due to the arrival of an astonishing array of new telescopes, novel instruments and innovative techniques. For those of us closely involved in developing new observatories, instrumentation or detectors, the last few years have been rather hectic! As an astronomer with a long-time interest in the development of new instruments, what amazes me is the breadth of technology and the visionary scope of all these incredible new achievements. Many of the very large 8-10 meter class telescopes are now coming into full operation – yet, just as this is happening, numerous smaller “survey” telescopes are providing a wealth of new sources. Adaptive optics is being practiced at many sites and diffraction-limited imaging from the ground is now a reality. Several optical-IR interferometers are now working and more are coming along very soon. Detectors continue to get bigger and better, especially for the infrared, and instrumentation is increasingly more sophisticated, complex and efficient. Remote observing, robotic telescopes and global networks of telescopes are common, and international collaborations are larger and stronger than ever before.

The work of Commission 25 covers a wide range of topics concerning the measurement of magnitude, colour and polarisation of astronomical objects. As such, the area of interest covers virtually every field of astrophysical research in the visual and infrared spectral domain. Our reports cover some aspects of photometry and polarimetry as a technique rather than being an account of research highlights over the last three years.

In 1988, a Joint Commission (9 and 25) meeting on the causes of the well-known limitations on the precision of infrared astronomy led to several suggestions to improve matters (see Milone 1989). These included better reporting of the photometric systems in use by practitioners, redesign of the infrared passbands to be more optimally placed inside the atmospheric windows, and development of a method to ascertain the water vapor content of the atmosphere when the astronomical infrared measurements were being made. An Infrared Astronomy Working Group was formed to look into the matter. Advice and suggestions were solicited from the community at large. All who volunteered information became, de facto, members of the Working Group. A small subgroup composed of Andrew Young, Chris Stagg, and Milone set to work on the central of the recommendations: improvement of the passbands. Young, Milone, k Stagg (1994) (hereafter YMS) summarized the work: existing JHKLMN and Q infrared passbands were found to be both far from standardized, and all too frequently defined, to various degrees, by the water vapor and other components of the terrestrial atmosphere. Following extensive numerical simulations with a MODTRAN 3 terrestrial-atmospheres model package, and Kurucz stellar atmospheres, we suggested a set of improved infrared passbands designed explicitly to fit within, and not be defined by, the terrestrial atmospheric windows; however, we sought to optimize them so as to get the maximum throughput consistent with plausible limitations on precision of manufacture of the filters. In 1995 and again in 1997, a number of improvements were made in the code with which the improved passbands were designed. While they do not much affect the optimization trials and thus the passband recommendations, they have been used to extend the modeling.

Commission 30 has 120 members in 28 countries who are active in the area of radial velocities. During the past triennium 11 new members have joined the commission. The work of the commission covers a wide range of topics all of which concern the application of the Doppler effect to astronomical objects, including galaxies and the interstellar medium as well as stars, and in all wavelength ranges of the electromagnetic spectrum. Although the commission focuses mainly on stellar and galaxy radial velocities, it is noted that stellar rotation, spectroscopic binaries, extrasolar planet searches, pulsating variable stars, asteroseismology and turbulence in stellar atmospheres are also included.

Radio astronomy has seen major advances in both instrumentation and scientific discovery during the last three years. This report is not encyclopedic but is intended to show the breadth of activity in the field. Division X is a technique-based division, and radio telescopes are becoming increasingly more international in character and usage. For these reasons this report devotes considerable attention to advances in instrumentation. More complete information on radio telescopes and scientific advances in the field can be found at the following Web site: http://www.stsci.edu/science/net-resources.html

The reporting period has shown that Space has become a firmly established domain in observational Astrophysics, also in the low energy astrophysics area. The launching of new spacecraft is always an important addition to the capabilities of the Astronomers, but the availability of space observatories is strongly affected by the fact that they disappear as their subsystems become damaged or, for other reasons, become inoperable. The relatively short life of astronomical space facilities has generated new dynamic in the life cycle of observational tools for the astronomer, rather different from that for ground facilities. Launch failures or the final in-orbit functionality verification can also very strongly affect the availability of observational capabilities in space astrophysics. The only spacecraft designed without this built-in life time restriction, is the Hubble Space Telescope, which can be serviced by the Space Shuttle.

Four working groups and three task groups of IAU Commission 5 deal specifically with information handling, technical aspects of collection, archiving, storage and dissemination of data, with designations and classification of astronomical objects, with library services, editorial policies, computer communications, ad hoc methodologies, and with various standards, reference frames etc. Information about Commission 5 working and task groups and their activities may be found in http://nut.inasan.rssi.ru/IAU/.

Throughout the triennium, Commission 6 has interacted with the Central Bureau for Astronomical Telegrams (CBAT), most ably headed by Brian Marsden. As will be seen from his report below, the use by scientists of the Circulars for rapid dissemination of astronomical and related news continues unabated.

In recognition of its special interdisciplinary character, IAU Commission 14 is linked directly to the Executive Committee. The Commission’s role is to inform the astronomical community of new developments in the diverse fields of research which involve atoms and molecules. Conversely it endeavors to sensitize the research community active in those fields to the specific needs of astronomy, especially concerning basic data and modeling tools. More generally, Commission 14 tries to foster long term relations and collaborations between the two communities and, when necessary, to alert funding authorities to the specific needs of ground and space based astronomy for specific atomic and molecular data. This report is one of the main contributions of Commission 14 to the information of the astronomical community. Several meetings concerned, at least in part, with the need and availability of atomic and molecular data for astrophysics were also sponsored or co-sponsored. In the last triennium, Commission 14 cosponsored IAU Symposium 194 “Astrochemistry: From Molecular Cloud to Planetary Systems” held in Sogwipo (Korea) from Aug. 23 to 27, 1999 and organized by Commission 34. A Joint Discussion: JD1 on “Atomic and Molecular Data for Astrophysics, New Developments, Case Studies and Future Needs” has been planned for the XXIVth IAU General Assembly in Manchester (Aug. 7-19, 2000) and cosponsored by Commissions 15, 16, 29, 34, 36, 40 and 44. Several other Joint Discussions to be held at the Manchester General Assembly are co-sponsored by this commission.

Thirty five grants were made during the triennium October 1, 1996 to September 30, 1999. The astronomer, home country, and host country are listed below.

Commission 46 is dedicated to Teaching of Astronomy. Commission 46 can be seen as an extension of the IAU Executive Committee in the sense that each adhering country has appointed a national representative to the Commission. National Representatives maintain liaison between the Commission and the home country, and write national triennial reports on development of astronomy on their nations. Other IAU astronomers, with special interest in education, can become regular individual members of the Commission. Non-IAU members can be invited by the Commission to serve for one triennial term. Commission 46 considers that one of its major duties is to contribute to enhance astronomy education in developing countries. The Newsletter, the International School for Young Astronomers, the Visiting Lecturer Program and the Travelling Telescope are examples of such activities administered by the Commission. The strength of Commission 46 comes from the hard work that its members do in order to promote astronomy education worldwide.

The chief activities of the Commission for this period were the organizing of two important meetings. The first was held as Joint Discussion 5 at the Kyoto General Assembly in August 1997. The proceedings have now appeared as “Preserving the Astronomical Windows”, edited by S. Isobe (1997).

The membership of the Commission, as of its 50th anniversary in 1998, stands at 146 members and 19 consultants. In order to increase communications, during the report period the President issued six Newsletters to Commission members, consultants, and IAU officers. In a further attempt to increase communications, Commission 41 also instituted a web site (http://www.astro.uni-bonn.de/~pbrosche/iaucomm41/) in early 1998. This was largely due to the efforts of C41 Organizing Committee member Wolfgang Dick and the kindness of Professor Peter Brosche in supplying space. The site not only contains the Newsletters, meeting notices, and a list of members, but also the Bibliography on History of Astronomy, compiled by Ruth Preitag of the Library of Congress in Washington, D.C. The site also links to the history of astronomy site maintained for several years by the History of Astronomy Working Group of the Astronomische Gesellschaft, and now also maintained on behalf of Commission 41. These sites serve not only for better communication among Commission members, but also the broader history of astronomy community.

Since July 1996, 815 new names on features on bodies in the Solar System have been assigned by the WGPSN and approved at the IAU General Assembly in Kyoto in 1997. Of these names, 666 were for Venus, 17 for Mars, 3 for the Moon, 125 for the Galilean satellites, 3 for the Uranian satellite Miranda, and 1 for the minor planet Ida. 71 additional names mostly on Venus have been selected and have been given or are awaiting provisional approval by the IAU Executive Committee (EC). These names are up for final approval at the next IAU General Assembly.

The Working Group often overlaps in responsibilities with other Commissions, particularly with Commission 46. Some projects (e.g. TAD) may begin on the initiative of our Group but are maintained by Commission 46. TAD programmes are now running in Viet Nam and Central America and one will begin soon in Morocco. Preliminary inquiries have been received from other countries.

The idea for a Working Group (WG) on “Future Large Scale Facilities in Astronomy” grew from the Joint Discussion on this topic held on 20 August 1994, during the IAU General Assembly in The Hague. The IAU Executive Committee approved its formation in August, 1995, and Harvey Butcher was chair until the XXIIIrd General Assembly in Kyoto in 1997.