This report gives a brief overview of some of the activities and developments in extragalactic research over the past three years.

Even a brief glance at astronomical journals indicates the breadth and depth of observational projects making use of photometric and polarimetric techniques. Examples of ongoing photometric and polarimetric research as related by Commission Members follows. I thank the Commission Members, acknowledged below, for their input.

The interests of Division VII encompass the Milky Way Galaxy and it comprises two commissions: 33–Structure and Dynamics of the Galactic System and 37–Star Clusters and Association.

The IAU Division IV (‘Stars’) organizes astronomers studying the characteristics, interior and atmospheric structure, and evolution of stars of all masses, ages, and chemical compositions.

During the triennial starting at the Sydney General Assembly in August 2003, the following o.cials served in Division IV: President – Dainis Dravins (Lund, Sweden); Organizing Committee – Beatriz Barbuy (São Paolo, Brazil; former Div.IV president); Christopher Corbally (Vatican & Tucson, USA; Comm. 45 President); Wojciech Dziembowski (Warsaw, Poland; Comm. 35 President); William Hartkopf (Washington DC, USA; Comm. 26 President); Christopher Sneden (Austin, USA; Comm. 29 President), and Monique Spite (Paris-Meudon, France; Comm. 36 President).

As is evident from Director Dan Green's detailed report below, the Central Bureau for Astronomical Telegrams (CBAT) continues to function in a very reliable and efficient way. The electronic telegrams (CBETs) introduced in 2002 have proved to be a great success; they allow for very rapid dissemination of more extensive information than there is room for on printed Circulars, and they are frequently cited in the astronomical literature. The workload on the Director seems to be forever increasing. It is therefore gratifying that an Assistant Director, Gareth Williams, has been appointed. Since he also serves as Associate Director of the Minor Planet Center (MPC) and performs many of the computations on which the CBETs and the Circulars are based, the ties and mutual benefits between the CBAT and the MPC have been made even stronger.

This report, like its predecessors, focuses on areas which have been especially active since the last General Assembly. Two major developments have been the unification of the T-dwarf standards and the new general catalogue of stellar spectral classifications.

Historically, there have been two main groups dealing with the investigation of extraterrestrial life and habitable worlds. The first is IAU Commission 51, composed of astronomers, physicists and engineers who focus on the search for extrasolar planets, formation and evolution of planetary systems, and the astronomical search for intelligent signals. The second group, the International Society for the Study of the Origin of Life (ISSOL), is composed largely of biologists and chemists focusing research on the biogenesis and evolution of life on Earth and in the solar system. There are now a variety of international organizations dedicated to this field, and this triennium has seen the beginnings of coordination and interaction between the groups through the Federation of Astrobiology Organizations, FAO.

The Program Group for the World-wide Development of Astronomy (PGWWDA) is one of nine Comm. 46 program groups engaged with various aspects of astronomical education or development of astronomy education and research in the developing world. In the case of PGWWDA, its goals are to promote astronomy education and research in the developing world through a variety of activities, including visiting astronomers in developing countries and interacting with them by way of giving encouragement and support.

IAU Division I includes Commission 4 (Ephemerides), Commission 7 (Celestial Mechanics and Dynamical Astronomy), Commission 8 (Astrometry), Commission 19 (Rotation of the Earth) and Commission 31 (Time). The Division has in addition five Working Groups on, respectively, Future Development of Ground-Based Astrometry, Nomenclature for Fundamental Astrometry, Definition of Coordinated Universal Time, and Precession and the Ecliptic.

This triennial report from Comm. 14 covers the topics Atomic Spectra and Wave-length Standards, Atomic Transition Probabilities, Collision Processes, and Line Broadening.

The definition of UTC was implemented in 1972, principally to accommodate celestial navigation and follows recommendation 460 of the International Radio Consultative Committee (CCIR) in 1970. Since 1972 the use of electronic means to navigate has overtaken celestial navigation. This fact along with increasing public dissatisfaction with the possible disruption to modern electronic communications and navigation systems caused by the insertion of a leap second has called into question the current definition of UTC. An extensive review of the background and issues relating to the leap second can be found in Nelson, et al (2001).

Participants in Commission 29 study various aspects of stellar spectra and the information that can be extracted from spectra. The list of fields of interest of the Organizing Committee members suggest some major current research topics in this area are stellar chemical compositions and surface/envelope phenomena. Some of the topics of this commission have overlap with other commissions, such as Commission 14 (Atomic and Molecular Data), 26 (Double and Multiple Stars), 27 (Variable Stars), 30 (Radial Velocities), 36 (Theory of Stellar Atmospheres), and 37 (Star Clusters and Associations). Many Commission 29 members are also members of these other commissions.

The most intensely discussed and controversial issue in time keeping has been the proposal before the International Telecommunications Union (ITU) to redefine Coordinated Universal Time (UTC) so as to replace leap seconds by leap hours. Should this proposal be adopted, the practice of inserting leap seconds would cease after a specific date. Should the Earth's rotation continue to de-accelerate at its historical rate, the next discontinuity in UTC would be an hour inserted several centuries from now. Advocates of this proposal cite the need to synchronize satellite and other systems, such as GPS, Galileo, and GLONASS, which did not exist and were not envisioned when the current system was adopted. They note that leap second insertions can be and have been incorrectly implemented or accounted for. Such errors have to date had localized impact, but they could cause serious mishaps involving loss of life. For example, some GPS receivers have been known to fail simply because there was no leap second after a long enough interval, other GPS receivers failed because the leap second information was broadcast more than three months in advance, and some commercial software used for internet time-transfer Network Time Protocol (NTP) could either discard all data received after a leap second or interpret it as a frequency change. The ambiguity associated with the extra second could also disrupt financial accounting and certain forms of encryption. Those opposed to the proposal question the need for a change, and also point out the costs of adjusting to the proposed change and its inconvenience to amateur astronomers and others who rely upon astronomical calculations published in advance. Reports have been circulated that the cost of checking and correcting software to accommodate the new definition of UTC would be many millions of dollars for some systems. In October 2005 American Astronomical Society asked the ITU for a year's time to study the issue. This commission has supported the efforts of the IAU's Committee on the Leap Second to make an informed recommendation, and anticipates considerable discussion at the IAU's 26th General Assembly in 2006.

JPL continues to be active in creating ephemerides in support of spacecraft navigation as well as various other functions. Many of the products are available on web sites: (a) “Horizons”, the interactive web site, updated on an hourly basis, is located at http://ssd.jpl.nasa.gov. As of August, 2005, it contains orbital elements and ephemerides for the sun and 9 planets, 150 natural satellites (including the Moon), 291, 655 asteroids, 1631 comets, and 34 Spacecraft. Horizons uses the full precision of the JPL DE405.

(b)JPL's Planetary and Lunar Ephemerides in “export” format are available via FTP from the Internet: ftp://ssd.jpl.nasa.gov/pub/eph/export/ or on a CD-ROM: http://www.willbell.com/software/jpl.htm We advise to read the attached README.

(c)The observational data used in fitting the planetary ephemerides is available at the following web site, updated periodically: http://ssd.jpl.nasa.gov/plan-eph-data/

(d)SPICE Toolkit is a subroutine package for experienced programmers who write their own main driving programs for astrometrical computations. SPICE is available at http://naif.jpl.nasa.gov/. It contains a large library of subroutines useful in reading SPICE format ephemeris files (SPK) and in computing many solar system observation geometry parameters associated with the various JPL solar system missions. Available in Fortran, C, and IDL for most popular computing platforms.

Following the Sydney General Assembly, the membership of C41 stood at 352, of whom, at the time of writing, three are known to have deceased. Since the formation of the Inter-Union Commission for the History of Astronomy (ICHA) prior to the Sydney General Assembly, C41/ICHA has subsequently acted, in effect, as an integrated Commission with a single OC. In this triennium the C41/ICHA OC made strong efforts to clarify and simplify the controversial issue of admitting non-IAU members to the ICHA. After prolonged and active consultation, the OC approved the document “Procedures for Admitting non-IAU members to the ICHA” and the OC Secretary Prof. Clive Ruggles officially presented this document to the history of astronomy community in C41/ICHA Newsletter no. 6. It is subject to ratification by the C41/ICHA Business Meeting in Prague in 2006.

We report the major highlights of variable star research within the past three years. This overview is limited to intrinsically variable stars, because the achievements in variable star research stemming from binarity, or multiplicity in general, is covered by the summary report of Commissions 26 and 42.

The triennial report of Commission V Documentation and Astronomical Data/Documentation et Données Astronomiques covers 2002–2005 activities, and in particular the activities of the five Working Groups: Working Group Astronomical Data; Working Group Designations; Working Group Libraries; Working Group FITS; Working Group Virtual Observatories; and of Task Force for the Preservation and Digitization of Photographic Plates.

Commission 12 covers research on the internal structure and dynamics of the Sun, the “quiet” solar atmosphere, solar radiation and its variability, and the nature of relatively stable magnetic structures like sunspots, faculae and the magnetic network. There is considerable productive overlap with the other Commissions of Division II as investigations move progressively toward the fertile intellectual boundaries between traditional research disciplines. In large part, the solar magnetic field provides the linkage that connects these diverse themes. The same magnetic field that produces the more subtle variations of solar structure and radiative output over the 11 yr activity cycle is also implicated in rapid and often violent phenomena such as flares, coronal mass ejections, prominence eruptions, and episodes of sporadic magnetic reconnection.

The last three years have again brought significant progress in nearly all the research endeavors touched upon by the interests of Commission 12. The underlying causes for this success remain the same: sustained advances in computing capabilities coupled with diverse observations with increasing levels of spatial, temporal and spectral resolution. It is all but impossible to deal with these many advances here in anything except a cursory and selective fashion. Thankfully, the Living Reviews in Solar Physicsacute; has published several extensive reviews over the last two years that deal explicitly with issues relevant to the purview of Commission 12. The reader who is eager for a deeper and more complete understanding of some of these advances is directed to http://www.livingreviews.org for access to these articles.

This document introduces the reports by the Commissions and Working Groups of Division IX.

Commission 36 covers all the physics of stellar atmospheres. The scientific activity in this large field has been very intense during the last triennium and led to the publication of a large number of papers which makes an exhaustive report practically not feasible. As a consequence we decided to keep the format of the preceding report: first a list of areas of current research, then web links for obtaining further information.