Due to the adoption of the new International Celestial Reference Frame (ICRF), the Earth’s Ori-entation Parameters (EOP) will be revised and their definitions will need to be re-examined and clarified. This implies that precession/nutation formulation will be also revised in the future.

The precession/nutation theories for a non-rigid Earth suffer from a lack of dissipation in the core and from a mismodeling of the ocean and of the atmospheric effects. The scientific community is examining these questions. The IAU community is consequently not yet ready to adopt a new precession/nutation geophysical model but the users may use the International Earth Rotation Service (IERS) empirical series.

In order to review those questions and prepare the future research, the Scientific Organizing Committee (SOC: P. Bretagnon, V.A. Brumberg, N. Capitaine, V. Dehant (Chair), T. Fukushima, E. Groten, H. Kinoshitä, B. Kolaczek, D.D. McCarthy, P.K. Seidelmann and P.T. Wallace) has proposed invited talks on the current situation concerning:

1. (1) the formulation of precession/nutation (N. Capitaine, see paper 1),

2. (2) the planetary theories and their relation to precession/nutation (P. Bretagnon, see paper 2),

3. (3) the precession/nutation for a rigid Earth (J. Souchay and H. Kinoshita, see paper 3),

4. (4) the DExxx JPL ephemerides precision and accuracy (E.M. Standish, see paper 4),

5. (5) the observations of the Celestial Ephemeris Pole (CEP) and in particular the pole offset from which precession/nutation corrections can be derived (M. Feissel and A.M. Gontier, see paper 5),

In the fall of 1920 two young scholars happened to meet in London and found they had many interests in common in laboratory spectroscopy and astrophysics. One was an Indian and the other a Japanese, and their paths crossed as they visited American and European centers to learn the tools and techniques of the quantum theory. The young Japanese scholar, T. Takamine, whose home base was then the Institute of Physical and Chemical Research in Tokyo, was delighted to have met Meghnad Saha, from Calcutta, who was just putting the finishing touches on his fourth paper on ionization equilibrium in the atmospheres of the sun and stars. When they met, Takamine and Saha spoke of Sommerfeld’s theories, and pledged to keep in touch. Thus began a correspondence that lasted for some twenty years, as Takamine returned to Japan from his long visits to American and European observatories and spectroscopic laboratories, and Saha returned to India. Of the two, Takamine had stayed the longer time in the West, mainly at Mount Wilson where he was in residence through much of 1919 working with John Anderson and A. S. King, and published on the ”The Stark Effect for Metals.” Takamine also returned to Mount Wilson in 1924, and toured many spectroscopic laboratories in the United States continuing to hone his interests and technique. Elsewhere I have examined Saha’s contacts with western astrophysics. Here I examine briefly how Takamine established and maintained contacts in the West and why he did so.

This paper describes the conventional models for precession and nutation, the current procedure for taking them into account in the reduction of highly accurate observations, the recent IAU recommendations on this topic, as well as the current situation for theory and observations. This emphasizes the imperfections in the conventional models and in the current procedure which are not in consistency either with the adoption of the new International Conventional Celestial Reference System (ICRS) or with the high accuracy and resolution of the current observations of Earth rotation. This addresses the question of the adoption of a new formulation and of an improved model combining precession and nutation of the equator with respect to the ICRS as well as the adoption of a revised definition of the Celestial Ephemeris Pole.

In the IAU, there is the Commission 46 “Teaching of Astronomy” to which at least one representative from each member country belongs. At an occasion of the Asian-Pacific regional meeting of the IAU held in Beijing in 1987, there was a resolution to set up a committee of Teaching of Astronomy in the Asian-Pacific region. Since then, a session of the Teaching of Astronomy has been hold at each regional meeting.

In this paper, I give the present state of the analytical planetary theories by describing the general theories and the secular variation theories, the variations of the ecliptic with respect to the ecliptic J2000, the utilization of the analytical planetary theories in the calculation of the precession-nutation of the equator and in the calculation of the expressions of transformation between the barycentric and geocentric reference systems. At last, I describe the construction of new planetary theories undertaken at the Bureau des longitudes.

The analytical planetary theories arise in two forms: the general theories give, with a low accuracy, the variations of the elements of the planets over several million years; the secular variation theories reach a high accuracy over time spans of a few thousands of years.

In all these solutions, the motion of the planets is represented with 6 elements: a, the semi major axis, λ, the mean longitude and the variables k = e cos ϖ, h = e sin ϖ, q = sin ½ cos Ω, p = sin ½ sin Ω where e represents the eccentricity of the orbit, w the longitude of the perihelion, i the inclination of the orbit about the ecliptic J2000 and Ω the longitude of the node.

Recently Catherine Jami and I have found the manuscript of the Lifa wenda Dialogue on Astronomy) by Jean-Francois Foucquet (Fu Shengze , 1665-1741) at British Library. Together with the other, partial, but, otherwise identical, version, which she had located at the Vatican Apostolic Library, the manuscript, especially Book V, Part 1, from the British Library, gives us the detail of how Kepler’s forst and second Laws was introduced into China as early as in the 1710’s. This means that we can go back in the history of the introduction more than two decades earlier than the so far believed date.

Whereas no particular attention was paid to the theory of the nutation for a rigid Earth model, for more than a decade after the adoption by the International Astronomical Union (IAU) of coefficients as calculated and listed by Kinoshita (1977), an increasing number of studies have been done in the recent years aiming to improve this theory. The improvement became necessary mainly because of the big parallel improvement of the VLBI observations itself, which leads to present determinations of some coefficients of nutation at the level of a few 10μas. Therefore the amelioration of the theory of the nutation for a rigid Earth model can be divided in two aspects: one is to consider a smaller level of truncation of the coefficients of nutation; the other is to evaluate in the best way the coefficients already taken into account, particularly the leading coefficients which are typically those subject to the largest absolute differences.

There are of the order of 30 astronomers with research records and another 40-50 with substantial education in astronomy and astrophysics. Geographically, astronomical and astrophysical research is concentrated mainly at Shiraz University (cosmology and photometric observations), Sharif University of Theran (cosmology and gamma-ray astronomy), Tabriz University (binaries and solar physics), Meshad University (binaries and interstellar matter), Zanjan University (stellar dynamics, radio astronomy) and the Institute for Advanced Studies in Basic Sciences, Zanjan (stellar and stellar systems studies).

The period 1850-1910 was a “golden age” in Australian astronomy, with the establishment of professional observatories, substantial growth of popular interest in astronomy, establishment of a network of significant private observatories across the nation, and formation of Australia’s earliest astronomical groups and societies.

During this period, amateur astronomers were able to make a significant contribution internationally to positional astronomy. This paper briefly examines amateur-professional relations in Australian astronomy at the time, and the interplay of power and politics.

The latest JPL planetary and lunar ephemerides, DE405, are now referenced to the ICRF with an accuracy of about 1 mas. This has been accomplished mainly by fitting the ephemerides to 18 VLBI observations of the Magellan Spacecraft in orbit around Venus, 1990-1994, and to 2 VLBI observations of the Phobos Spacecraft in its approach to Mars, 1989. The orientation of DE405 is discussed in more detail elsewhere in this volume (Standish, 1997). Since all of the parameters of the inner solar system are now determined to 1 mas or better, one should be able to extract numerically the fundamental arguments of the nutation theories to the level of 1 mas.

There are two ways of extracting the ecliptic, for example, from a numerical ephemeris: 1) one computes the node and obliquity of the instantaneous ecliptic at multiple points in time and then fits these with analytic functions, or 2) one fits an analytical planetary theory to the ephemerides and then computes the node and obliquity from the theory’s parameters. This paper relates a short example using method #1 and concludes that method #2 is probably more preferable.

The accurate observation of the celestial motion of the Earth’s pole requires careful connection of the VLBI observables with quantities and reference frames related to the theoretical description of precession-nutation models. The analysis of the derived celestial pole offsets beyond the semi-empirical IERS(1996) precession-nutation model shows variability of some components, such as the seasonal term and a ~ 430 day term.

Delisle, born in 1688 April 4, is well known as a collector of astronomical data from all over the world. Part of his manuscripts are preserved in the Paris Observatory Library. He is said to have collected all available astronomical data at the time he was in activity in France and in Russia where he spent more than twenty years. He had more correspondents and among them, in Asia, Father Gaubil, of which more than one hundred letters are in the Paris Observatory Archives, providing priceless informations to astronomical researchers, historians and others.

Over the last few decades phenomena involving high energy particles (mostly electrons) and/or photons have become increasingly part of the astronomical work. Opening new spectral windows has revealed many phenomena that have deeply changed our perception of the Universe. High energy astrophysics, as this field of astronomy is known, is now very well integrated in the astronomical research. This is shown by the fact that the high energy astrophysics results are published in the leading astronomy and astrophysics journals of the world rather than anywhere else. Nonetheless, this still young field has not yet quite found its way in the structure and working of the IAU.

The whole scope of problems related with the rotational motion of celestial bodies is briefly discussed. Relativistic modeling of the Earth rotation is considered from a conceptual point of view. Relativistic effects in rotational equations of motion of an extended body in general relativity are discussed. Numerical values of the effects are given.

The IERS nutation series was developed as a nutation series which would match observations and could be used with geodetic systems which have sensitivity to nutations but are not able to determine accurately corrections to the IAU-1980 nutation series. After experimentation with different methods for parameterizing the nutation estimation problem, the best fit to the VLBI observed nutation angle data was found by estimating selected coefficients in the Mathews et al. (1991a) nutation response function (see equation (1) below), along with other parameters to be discussed below. The estimation of the response function coefficients was also found to account for mantle anelasticity and the loading part of the ocean tide correction and therefore no corrections were applied for these effects. Their contributions should be absorbed into the estimated response coefficients. These initial analyses also showed: setting the inner-core response to zero yielded better fits to the nutation angle data than the Mathews et al. (1991b) theoretical response and resonance frequency; the amplitude of the RFCN free mode appeared to be time dependent; and the prograde annual nutation was significantly affected by the SI thermal tide which is not proportional to the S1 gravitational potential.

The data set used to estimate the IERS conventions series was the GSFC nutation angle data set with 2040 pairs of adjustments to the IAU 1980 nutations in obliquity and longitude spanning the interval between 1979 and 1995. Here we also compare the IERS conventions series with a US Naval Observatory analysis of VLBI data between 1979 and August 1997. This data set consists of 2152 pairs of nutation angle estimates and extends by 1.8 years the interval covered by the GSFC data set. It also contains less pre-1984 data than the GSFC data set which accounts for the smaller increase in total number of observations than would be expected for the additional time interval covered.

I have been asked to provide some general introduction to the topic of jets and high energy transients. I have chosen to do this by asking seven questions that seem to be timely following recent observational and theoretical developments, the most important of which may be the growing realization that the extragalactic- massive black hole and Galactic-stellar mass black hole manifestations of these phenomena provide two complementary ways of viewing a common physical mechanism. I have also chosen to illustrate these questions using one specific source in each case. The page limits prevent me from giving the answers. They also prohibit my even attempting to give a skeletal bibliography over so large a field. Fortunately almost all of these topics will be covered in greater depth during this meeting.

We present a first description of the changes in the current procedures that will have to be performed in order to take into account the adoption of the ICRS as the new reference system and new nutation-precession series. A number of choices will have to be made: they are presented in this paper.

In the last solar maximum, gamma-rays associated with solar flares were observed with GRANAT, GAMMA-1, CGRO and YOHKOH. The gamma-ray energies ranged from 100 keV to a few GeV. We obtained several new findings of gamma-ray emission on the Sun: (1) Gamma-ray production in the corona, (2) GeV gamma-ray production in very long duration flares, (3) Electron-rich flares, (4) Gamma-ray lines and solar atmospheric abundances and (5) Possible location of gamma-ray emission. We present the observations of these new findings and discuss high energy phenomena relating to particle acceleration and gamma-ray production during solar flares.

We review recent results obtained from the analysis of the solar flare gamma ray line emission:

• (a) The gamma ray derived ambient elemental abundances show that the First Ionization Potential (FIP) effect already sets in at relatively low altitudes in the solar atmosphere.

• (b) The composition of the flare accelerated particles that produce the gamma rays exhibit heavy element and 3He abundance enhancements that are typical for impulsive flares. Unlike the solar energetic particle (SEP) observations in interplanetary space, the gamma ray method allows us to trace the time development of these enhancements.

• (c) Solar flare gamma ray spectroscopy provides the most direct measure of the abundances of the two very high FIP elements, He and Ne, in subcoronal regions leading to somewhat higher abundances than the generally accepted values.

• (d) The high intensities of the aa lines observed from a number of flares imply a high (≳ 0.1) ambient He/H and/or accelerated α/p.

• (e) There are indications for the isotopic fractionation of He from the photosphere to corona that has important implications on the mechanism of solar wind acceleration, the protosolar deuterium abundance and Galactic chemical evolution.

Systematic errors caused by the use of inconsistent models and constants currently limit the accuracy of the most precise astro-geodetic observations. It is important, therefore, to provide conventional estimates of astronomical constants for general use in astronomy and geodesy. Establishment of such a set raises issues involving the accuracy of the constants, their internal consistency, and the reference system in which they are expressed. Future sets of constants will be updated at regular intervals to provide the most accurate values at that instant. Careful consideration must be given to their internal consistency. It is likely that they will be provided only in electronic format with references to their determination and to procedures for their use.