In the article by Crabtree et al., published in Transactions IAU, Volume XXVIIIA there was an error in the list of authors. Pedro Russo was not included in the list of authors on the organizing committee. The editors apologise to Pedro Russo for this error. The correct authorship is published below:

• PRESIDENT: Dennis R. Crabtree

• VICE-PRESIDENT: Lars Lindberg Christensen

• PAST PRESIDENT: Ian Robson

• ORGANIZING COMMITTEE: Oscar Alvarez Pomare, Augusto Damineli Neto, Richard T. Fienberg, Anne Green, Ajit K. Kembhavi, Pedro Russo, Kazuhiro Sekiguchi, Patricia Ann Whitelock, Jin Zhu

The goal of the division is to address the scientific issues that were developed at the 2009 IAU General Assembly in Rio de Janeiro. These are:

• • Astronomical constants

• —Gaussian gravitational constant, Astronomical Unit, GMSun, geodesic precession-nutation

• • Astronomical software

• • Solar System Ephemerides

• —Pulsar research

• —Comparison of dynamical reference frames

• • Future Optical Reference Frame

• • Future Radio Reference Frame

• • Exoplanets

• —Detection

• —Dynamics

• • Predictions of Earth orientation

• • Units of measurements for astronomical quantities in relativistic context

• • Astronomical units in the relativistic framework

• • Time-dependent ecliptic in the GCRS

• • Asteroid masses

• • Review of space missions

• • Detection of gravitational waves

• • VLBI on the Moon

• • Real time electronic access to UT1-UTC

The Commission 4 Organizing Committee began its work for the 2009-2012 triennium by revising the commission's terms of reference, which serve as our “mission statement.” The new terms of reference are:

1. (a) Maintain cooperation and collaboration between the national offices providing ephemerides, prediction of phenomena, astronomical reference data, and navigational almanacs.

2. (b) Encourage agreement on the bases (reference systems, time scales, models, and constants) of astronomical ephemerides and reference data in the various countries. Promote improvements to the usability and accuracy of astronomical ephemerides, and provide information comparing computational methods, models, and results to ensure the accuracy of data provided.

3. (c) Maintain databases, available on the Internet to the national ephemeris offices and qualified researchers, containing observations of all types on which the ephemerides are based. Promote the continued importance of observations needed to improve the ephemerides, and encourage prompt availability of these observations, especially those from space missions, to the science community.

4. (d) Encourage the development of software and web sites that provide astronomical ephemerides, prediction of phenomena, and astronomical reference data to the scientific community and public.

5. Promote the development of explanatory material that fosters better understanding of the use and bases of ephemerides and related data.

At the time this report was written, Commission 7 according to the IAU database had 304 registered members. The activities of Commission 7 in the past triennium closely followed the plan outlined at the business meeting of the Commission held on August 5, 2009 in Rio de Janeiro (Transactions IAU, Volume XXVIIB, 119-120).

Gaia is continuing well with its development and construction and is expected to achieve parallax accuracies of about 10 to 300 μas for 6 to 20 mag. It is scheduled to launch in 2013.

The ICRF2 was adopted by the IAU in 2009 as the new fundamental celestial reference frame.

The UCAC project concluded with the publication of its 4th data release (all-sky, over 100 million stars).

The JASMINE project will launch the Nano-JASMINE satellite in 2012 and continues with the development of its other satellites which will complement the Gaia project.

The PPMXL (Heidelberg) and XPM (Ukraine) catalogues provide improved astrometric accuracies from new reductions of USNO-B (USNO-A) and 2MASS data.

It is disappointing that the SIM project was cancelled during this triennium. It would have further complemented the above two satellite projects and would have gone even beyond Gaia in astrometric accuracy.

The Commission supports and coordinates scientific investigations about Earth rotation and related reference frames. Above all C19 encourages and develops cooperation and collaboration in observation and theoretical studies of Earth orientation (the motions of the pole in the terrestrial and celestial reference systems and the rotation about the pole). The Commission serves the astronomical community by linking it to the official organizations providing the International Terrestrial and Celestial Reference Systems/Frames (ITRS/ITRF and ICRS/ICRF) and Earth orientation parameters (EOP): International Association of Geodesy (IAG), International Earth Rotation and Reference System Service (IERS), International VLBI Service for Geodesy and Astrometry (IVS), International GNSS Service (IGS), International Laser Ranging Service (ILRS), International DORIS Service (IDS). Among the most important activities are the development of methods for improving the accuracy and understanding of Earth orientation and related reference systems/frames. Further, C19 ensures the agreement and continuity of the reference frames used for Earth orientation with other astronomical reference frames and their densifications and provides means of comparing observational and analysis methods and results to ensure accuracy of data and models.

IAU Commission 31 “Time” is part of Division I of the IAU. It currently has 103 members, a net increase of about 15% over the triennium, and 9 Consultants. The Commission web page is: www.atnf.csiro.au/iau-comm31/. It maintains a current membership list, with links to the IAU membership database, links to past and up-coming meetings related to Time and links to relevant websites and documents.

The IAU Commission 52 “Relativity in Fundamental Astronomy” (RIFA) has been established during the 26th General Assembly of the IAU (Prague, 2006). The general scientific goals of the Commission were identified as:

• • clarify geometrical and dynamical concepts of Fundamental Astronomy within a relativistic framework,

• • provide adequate mathematical and physical formulations to be used in Fundamental Astronomy,

• • deepen the understanding of the above results among astronomers and students in astronomy,

• • promote research needed to accomplish these tasks.

At the 2006 General Assembly of the International Astronomical Union (IAU), a proposal was adopted to form the Working Group (WG) for Numerical Standards of Fundamental Astronomy (NSFA). The goal of the WG is to update the “IAU Current Best Estimates" conforming with IAU Resolutions, the International Earth Rotation and Reference Systems Service (IERS) Conventions, and the Système International d'Unités (SI). The need for changes to the numerical standards are due mainly to the adoption of a new precession model, the redefinition of Barycentric Dynamical Time (TDB), and the significant improvement of the accuracy of recent estimates for a number of constants. The work from the first triennium culminated in the acceptance at the 2009 IAU General Assembly of Resolution B2 which adopted the NSFA list of Current Best Estimates as the IAU (2009) System of Astronomical Constants.

As in the past, the primary activity of the IAU Working Group on Cartographic Coordinates and Rotational Elements has been to prepare and publish a triennial (“2009”) report containing current recommendations for models for Solar System bodies (Archinal et al. (2011a)). The authors are B. A. Archinal, M. F. A'Hearn, E. Bowell, A. Conrad, G. J. Consolmagno, R. Courtin, T. Fukushima, D. Hestroffer, J. L. Hilton, G. A. Krasinsky, G. Neumann, J. Oberst, P. K. Seidelmann, P. Stooke, D. J. Tholen, P. C. Thomas, and I. P. Williams. An erratum to the “2006” and “2009” reports has also been published (Archinal et al. (2011b)). Below we briefly summarize the contents of the 2009 report, a plan to consider requests for new recommendations more often than every three years, three general recommendations by the WG to the planetary community, other WG activities, and plans for our next report.

The Working Group on the Natural Planetary Satellites has been created to promote the development of high-quality ephemerides. The Working Group encourages theoretical studies, coordinated observations, and makes all data available to the users through the NSDC web site (http://www.imcce.fr/nsdc).

The solar activity cycle entered a prolonged quiet phase that started in 2008 and ended in 2010. This minimum lasted for a year longer than expected and all activity proxies, as measured from Earth and from Space, reached minimum values never observed before (de Toma, 2012). The number of spotless days from 2006 to 2009 totals 800, the largest ever recorded in modern times. Solar irradiance was at historic minimums. The interplanetary magnetic field was measured at values as low as 2.9 nT and the cosmic rays were observed at records-high. While rumors spread that the Sun could be entering a grand minimum quiet phase (such as the Maunder minimum of the XVII century), activity took over in 2010 and we are now well into Solar Cycle 24 (albeit, probably, a low intensity cycle), approaching towards a maximum due by mid 2013. In addition to bringing us the possibility to observe a quiet state of the Sun and of the Heliosphere that was previously not recorded with modern instruments, the Sun has also shown us how little we know about the dynamo mechanism that drives its activity as all solar cycle predictions failed to see this extended minimum coming.

Commission 10 of the International Astronomical Union has more than 650 members who study a wide range of activity phenomena produced by our nearest star, the Sun. Solar activity is intrinsically related to solar magnetic fields and encompasses events from the smallest energy releases (nano- or even picoflares) to the largest eruptions in the Solar System, coronal mass ejections (CMEs), which propagate into the Heliosphere reaching the Earth and beyond. Solar activity is manifested in the appearance of sunspot groups or active regions, which are the principal sources of activity phenomena from the emergence of their magnetic flux through their dispersion and decay. The period 2008–2009 saw an unanticipated extended solar cycle minimum and unprecedentedly weak polar-cap and heliospheric field. Associated with that was the 2009 historical maximum in galactic cosmic rays flux since measurements begun in the middle of the 20th Century. Since then Cycle 24 has re-started solar activity producing some spectacular eruptions observed with a fleet of spacecraft and ground-based facilities. In the last triennium major advances in our knowledge and understanding of solar activity were due to continuing success of space missions as SOHO, Hinode, RHESSI and the twin STEREO spacecraft, further enriched by the breathtaking images of the solar atmosphere produced by the Solar Dynamic Observatory (SDO) launched on 11 February 2010 in the framework of NASA's Living with a Star program. In August 2012, at the time of the IAU General Assembly in Beijing when the mandate of this Commission ends, we will be in the unique position to have for the first time a full 3-D view of the Sun and solar activity phenomena provided by the twin STEREO missions about 120 degrees behind and ahead of Earth and other spacecraft around the Earth and ground-based observatories. These new observational insights are continuously posing new questions, inspiring and advancing theoretical analysis and modelling, improving our understanding of the physics underlying magnetic activity phenomena. Commission 10 reports on a vigorously evolving field of research produced by a large community. The number of refereed publications containing ‘Sun’, ‘heliosphere’, or a synonym in their abstracts continued the steady growth seen over the preceding decades, reaching about 2000 in the years 2008–2010, with a total of close to 4000 unique authors. This report, however, has its limitations and it is inherently incomplete, as it was prepared jointly by the members of the Organising Committee of Commission 10 (see the names of the primary contributors to the sections indicated in parentheses) reflecting their fields of expertise and interest. Nevertheless, we believe that it is a representative sample of significant new results obtained during the last triennium in the field of solar activity.

Commission 12 of the International Astronomical Union encompasses investigations of the internal structure and dynamics of the Sun, mostly accessible through the techniques of local and global helioseismology, the quiet solar atmosphere, solar radiation and its variability, and the nature of relatively stable magnetic structures like sunspots, faculae and the magnetic network. The Commission sees participation of over 350 scientists worldwide.

Commission 49 (Interplanetary Plasma and Heliosphere) is part of IAU Division II (Sun and Heliosphere). The research topics include large-scale solar disturbances such as coronal mass ejections (CMEs), shocks, and corotating interaction regions (CIRs) propagating into the heliosphere. The disturbances propagate through the solar wind, which essentially defines the heliosphere. The solar disturbances provide large-scale laboratory to study plasma processes over various time and spatial scales, the highest spatial scale being the size of the heliosphere itself (~100 AU). These solar disturbances are related to solar activity in the form of active regions and coronal holes. Solar eruptions are accompanied by particle acceleration and the particles can be hazardous to life on earth in various ways from modifying the ionosphere to damaging space technology and increasing lifetime radiation dosage to astronauts and airplane crew. Particle acceleration in solar eruptions poses fundamental physics questions because the underlying mechanisms are not fully understood. One of important processes is the particle acceleration by shocks, which occurs throughout the heliosphere. The heliosphere has both neutral and ionized material, with interesting interaction between the two components.

Division III, with 1126 members, is the third largest of the 12 IAU Divisions, focusing on subject matter related to the physical study of interplanetary dust, comets, minor planets, satellites, planets, planetary systems and astrobiology. Within the Division are very active working groups that are responsible for planetary system and small body nomenclature, as well as a newly created working group on Near Earth Objects which was established order to investigate the requirements for international ground-and/or space-based NEO surveys to characterize 90% of all NEOs with diameters >40m in order to establish a permanent international NEO Early Warning System.

Commission 53 was created at the 2006 Prague General Assembly (GA) of the IAU, in recognition of the outburst of astronomical progress in the field of extrasolar planet discovery, characterization, and theoretical work that has occurred since the discovery of the first planet in orbit around a solar-type star in 1995. Commission 53 is the logical successor to the IAU Working Group on Extrasolar Planets (WGESP), which ended its six years of existence in August 2006. The founding President of Commission 53 was Michael Mayor, in honor of his seminal contributions to this new field of astronomy. The current President is Alan Boss, the former chair of the WGESP. The current members of the Commission 53 (C53) Organizing Committee (OC) began their service in August 2009 at the conclusion of the Rio de Janeiro IAU GA.

Following its meeting in May, 2010, the IAU Executive Committee requested that a Working Group on NEOs within Div. III be re-activated and carry out the following activities:

1. a) investigate and formulate requirements for an international ground- and/or space-based NEO survey, to detect, track and characterize (optical/IR, radar) 90% of all NEOs with D >40 m and to establish as such a permanent International NEO Early Warning System; to submit to the President, Vice-President and OC of Division III by March 31, 2011, a progress report and by March 31, 2012, a final report on this matter, to be forwarded to the President and General Secretary of the IAU;

2. b) assemble a SOC in order to write and submit to the IAU Assistant General Secretary before December 1, 2010, a proposal for a GA IAU Symposium or a GA Special Session, to be held during the IAU XXVIII General Assembly, August 20-31, 2012 in Beijing, on theoretical and observational aspects of NEO research in general, and on requirements and other aspects of a permanent International NEO Early Warning System in particular;

3. c) prepare and submit to the IAU General Secretary by January 31, 2012, a Resolution for consideration by the IAU XXVIII General Assembly in Beijing, August 2012, asking for international action and support to establish an International NEO Early Warning System; such a Resolution, if accepted by the IAU XXVIII General Assembly, to be addressed to the IAU National Members, to the United Nations Committee on the Peaceful Uses of Outer Space (UN-COPUOS), and to the International Council for Science (ICSU).

The activity of the Minor Planet Center continued generally to increase during the triennium. This report covers the period 2008 July 1 to 2011 October 12, and the phrase “during the triennium” in this report should be understood to mean this period.

This Division IV was started on a trial basis at the General Assembly in The Hague 1994 and was formally accepted at the Kyoto General Assembly in 1997. Its broad coverage of “Stars” is reflected in its relatively large number of Commissions and so of members (1266 in late 2011). Its kindred Division V, “Variable Stars”, has the same history of its beginning. The thinking at the time was to achieve some kind of balance between the number of members in each of the 12 Divisions. Amid the current discussion of reorganizing the number of Divisions into a more compact form it seems advisable to make this numerical balance less of an issue than the rationalization of the scientific coverage of each Division, so providing more effective interaction within a particular field of astronomy. After all, every star is variable to a certain degree and such variability is becoming an ever more powerful tool to understand the characteristics of every kind of normal and peculiar star. So we may expect, after hearing the reactions of members, that in the restructuring a single Division will result from the current Divisions IV and V.