Recent optical and near-infrared surveys have considerably improved our knowledge of galactic structure and galactic evolution. Two ways can be used to infer this knowledge from datasets: either inversing the data to get parameters describing the Galaxy, or using a synthetic approaches to test scenarios of formation and theoretical models for star and galaxy formation and evolution, both approaches being complementary. Using the synthetic approach the Besancon Galaxy model allows to test scenarios for the structure and evolution of the Galaxy by comparing simulations with the survey data. Examples are given using the 2MASS survey. Future uses of astrometric survey data are shown to be able to efficiently constrain the kinematics and dynamics of the Galaxy.

Gaia, ESA's ambitious star-mapper mission due for launch late-2011, will provide multi-epoch micro-arcsecond astrometric and milli-magnitude photometric data for the brightest one billion objects in the sky, down to at least magnitude 20. Spectroscopic data will simultaneously be collected for the subset of the brightest 100 million stars, down to about magnitude 17. This massive data volume will allow astronomers to reconstruct the structure, evolution and formation history of the Milky Way. It will also revolutionize studies of the solar system and stellar physics and will contribute to diverse research areas, ranging from extra-solar planets to general relativity.

Underlying Gaia's scientific harvest will lie in a Catalogue, built on the fundamental space-based measurements. During the 5-year nominal operational lifetime, Gaia's payload, with its CCD mosaic containing 1 billion pixels, will autonomously detect all objects of interest and observe them throughout their passage of the focal plane. This paper discusses the workings of the Gaia instrument, details its payload, and discusses in depth how the scientific measurements will be collected. It addresses issues like maintenance of the scanning law, on-board data processing, the detection and confirmation of objects (single and multiple stars), the detection and rejection of cosmic rays and solar protons, the fundamental science measurements themselves composed of windows of CCD samples (pixels), and special strategies employed to maximize the science return for moving (i.e., solar-system) objects. The paper also explains how an on-board priority scheme will ensure catalogue completeness down to the faintest magnitudes possible, despite the limited ground-station availability and the enormous data volume that will be sent to the ground.

Based on our independently developed data processing software, the real-time reduction of the instantaneous state vectors of satellite during the maneuver stage near to perilune is analyzed via experimental observations. Results show that it is a quick and practical method to monitor the orbit evolution and the lunar capture of Chang'E-1 satellite.

JASMINE is the acronym of the Japan Astrometry Satellite Mission for INfrared (z-band: 0.9 micron) Exploration, and is planned to be launched around 2017. The main objective of JASMINE is to study the fundamental structure and evolution of the Milky Way bulge components. In order to accomplish these objectives, JASMINE will measure trigonometric parallaxes, positions and proper motions of about ten million stars in the Galactic bulge with a precision of 10 microarcsec at z = 14mag.

The primary mirror for the telescope has a diameter of 75cm with a focal length of 22.5m. The back-illuminated CCD is fabricated on a 300 micron thick substrate which is fully depleted. These thick devices have extended near infrared response. The size of the detector for z-band is 3cm×3cm with 2048×2048 pixels. The size of the field of view is about 0.6deg×0.6deg by using 64 detectors on the focal plane. The telescope is designed to have only one field of view, which is different from the designs of other astrometric satellites. JASMINE will observe overlapping fields without gaps to survey a total area of about 20deg×10 deg around the Galactic bulge. Accordingly we make a “large frame” of 20deg×10 deg by linking the small frames using stars in overlapping regions. JASMINE will observe the Galactic bulge repeatedly during the mission life of about 5 years.

The telescope geometry of JASMINE should be stabilized and monitored with the accuracy of about 10 to 100 pm or 10 to 100 prad of rms over about 10 hours. For this purpose, a high-precision interferometric laser metrology system is employed. Useful techniques for measuring displacements on extremely small scales are the wave-front sensing method and the heterodyne interferometrical method. Experiments for verification of measurement principles are well advanced.

This paper reports on our observing campaign of faint satellites performed at the National Time Service Center and Sheshan station of SHAO from 1994 up to today. In the past few years due to benefit from using a large size CCD and the publication of the modern catalogues (UCAC2), a series of observations of faint satellites were obtained by us. Moreover the work of improving the orbit of Phoebe via numerical fit to the observations over a century is also presented.

We present our search program for substellar companions using high-precisionrelative astronomy. Due to its orbital motion around the star, an unseensubstellar companion would produce a periodic “wobble” ofthe host star, which is the astrometric signal of the unseen companion. Bymeasuring the separation between the components of stellar double and triplesystems, we want to measure this astrometric signal of a possible unseencompanion indirectly as a relative and periodic change of these separations.Using a new observation mode (the “cube-mode”) where theframes were directly saved in cubes with nearly no loss of time during thereadout, an adaptive optics system to correct for atmospheric noise and aninfrared narrow band filter in the near infrared to suppress differentialchromatic refraction (DCR) effects we achieve for our first target (the doublestar HD 19994) a relative precision for the separation measurements of about100. . . 150μas per epoch. To reach a precision in the μas-regime, we use a statistical approach. We takeseveral thousand frames per target and epoche and after a verification of aGaussian distribution the measurement precision can be calculated as thestandard deviation of our measurements divided by the square root of the numberof Gaussian distributed measurements. Our first observed target is the stellarbinary HD 19994 A & B, where the A component has a known radialvelocity planet candidate.

We have studied the impact of long-term variability and surface brightness asymmetries on the parallaxes of long-period variable stars and red supergiants.

Different types of radiometric observations of planets and spacecraft, as well as optical data used for constructing modern high-precision planet ephemerides are presented. New mass values for planets and asteroids are given. The IAA RAS EPM ephemerides (Ephemerides of Planets and the Moon) are the basis for the Russian “Astronomical Yearbook” and are used in the navigation program “GLONASS” and the cosmic program “Phobos-Grunt”.

The PMOE planetary/lunar ephemeris framework was established in 2003, and has been improved in recent years. In the framework of the post-Newtonian effects, the figure perturbation effects arising from the a finite size of the Sun, Moon and the Earth, and the effect of the Earth tide were taken into account. The accuracy of using the PMOE ephemeris to predict the positions of the planets in the solar system are the same as that of JPL DE 405. Based on this framework, the orbit optimization for the LISA, ASTROD and ASTROD I missions, and the computation of celestial phenomena and lunar phases in the Xia Shang and Zhou period of ancient China have been completed.

TWA 5B is a brown dwarf companion of H=12 mag, 2″ off the ~5 mag brighter triple star CoD-33° 7795 (=TWA 5), a member of the TW Hydrae association of T Tauri stars at ~55 pc. This object is the first brown dwarf around a pre-main-sequence star (confirmed by common proper motion) ever found. In the last year we have newly reduced VLT NaCo data originally taken in 2003 and combined it with all the available astrometric data of the system to investigate possibly detectable orbital motion of the system. Indeed we were able to find linear orbital motion of the system combining data from HST, VLT and Gemini-North.

The Hipparcos and Tycho Catalogues were published in 1997. In the intervening 10 years, several thousand papers making more-or-less direct use of the data have been published. I summarise a number of scientific applications which illustrate the variety of problems to which the data have been applied. This includes the re-reduction of old and contemporary astrometric observations, investigations of Galactic structure and dynamics, investigations of stellar structure and evolution, investigations of the Solar System and our Earth's environment, and various uses of the binary star and photometric data.

Precision closure phase measurements obtained with ground-based long baselineoptical interferometers is a promising way to directly detect light from nearbyhot Jupiters. Here we present our closure phase simulations for the CHARA arrayfor several bright hot Jupiters, υ And b, 51 Peg b, and τBoo b. The maximum possible closure phase signals from these hot Jupiters arevery small, for example, only ∼0.17 degrees for υ And b,requiring very high precision and stable closure phase measurements. We presentpreliminary results of a closure phase study on test object β Tau andhot Jupiter system υ And, both obtained with the MIRC instrument atthe CHARA array. We demonstrate that directly detecting the light from hotJupiters is feasible using high precision closure phase measurements obtained byCHARA-MIRC along with its sub-milli-arcsecond resolution, although challengesremain.

As part of an astrometric program (see Loinard et al. in this volume), we have obtained an unprecedented sample of high-resolution (~ 1 mas) VLBA images of several nearby young stellar systems. As was to be expected, these images revealed interesting new characteristics of these objects. Perhaps the most interesting of these characteristics is the detection of a high rate of very tight binary stars (separations of a few mas) in our sample: of the 9 objects observed to date, 5 are binaries of this type.

The present system of astrometric education in the Saint-Petersburg State University is presented. The general courses, specific programs, seminars and observations that a student takes during a 5-year educational program are described.

The European Space Agency decision to include the Hipparcos satellite into its Science Programme is placed in the context of the years 1965-1980 and in the historical perspective of the progress of astrometry. The motivation and ideas which lead to the Hipparcos design are reviewed as well as its characteristics and performance. The amount and variety of applications represent an impressive evolution from the original science case and opened the way to much more ambitious further space missions, especially Gaia, based on the same basic principles. A giant step in technology led to a giant step in science. Next steps are presented at this Symposium.

Microlensing has proven to be a valuable tool to search for extrasolar planets of Jovian- to Super-Earth-mass planets at orbits of a few AU. Since planetary signals are of very short duration, an intense and continuous monitoring is required. This is achieved by ground-based networks of telescopes (PLANET/RoboNET, μFUN) following up targets, which are identified as microlensing events by single dedicated telescopes (OGLE, MOA). Microlensing has led to four already published detections of extrasolar planets, one of them being OGLE 2005-BLG-390Lb, a planet of only ∼5.5 M⊕ orbiting its M-dwarf host star at ∼2.6 AU. Very recent observations (May–September 2007) provided four more planetary candidates, still under study, that will double the number of detections. For non-planetary microlensing events observed from 1995 to 2006 we compute detection efficiency diagrams, which can then be used to derive an estimate of the Galactic abundance of cool planets in the mass regime from Jupiters to Sub-Neptunes.

We present the adaptive optics assisted, near-infrared VLTI instrument GRAVITY for precision narrow-angle astrometry and interferometric phase referenced imaging of faint objects. With its two fibers per telescope beam, its internal wavefront sensors and fringe tracker, and a novel metrology concept, GRAVITY will not only push the sensitivity far beyond what is offered today, but will also advance the astrometric accuracy for UTs to 10 μas. GRAVITY is designed to work with four telescopes, thus providing phase referenced imaging and astrometry for 6 baselines simultaneously. Its unique capabilities and sensitivity will open a new window for the observation of a wide range of objects, and — amongst others — will allow the study of motion within a few times the event horizon size of the Galactic Center black hole.

We present the results of a wide-field, high-precision UBVIc CCD photometric survey of the Galactic open cluster Blanco 1. Standardized photometry was acquired using the Y4Kcam on the SMARTS 1m telescope at CTIO. We have also determined new high-precision proper motions (σμ = 0.3 mas yr−1) over an eight square degree area down to V = 16.5. Combined with 1D kinematic data, our survey yields a complete list of cluster members down to ~ 0.5 M⊙ and new high-fidelity color-magnitude diagrams are presented for Blanco 1. Having established a bona fide membership catalog, astrophysical characteristics of solar-type cluster members such as X-ray activity and lithium abundance have been studied to gain more insights in the process of internal mixing and convection. Our new results should also help to better understand its peculiar location in the Milky Way and to unravel its dynamical history.

Gaia photometric capabilities should distinguish quasars to a high degree of certainty. With this, they should also be able to deliver a clean sample of quasars with a negligible trace of stellar contaminants. However, a purely photometric sample could miss a non negligible percentage of ICRF sources counterparts - and this interface is required to align with the ICRS and de-rotate the GCRF (Gaia Celestial Reference Frame), on grounds of continuity. To prepare a minimum clean sample forming the initial quasar catalogue for the Gaia mission, an all sky ensemble was formed containing 128,257 candidates. Among them there is at least one redshift determination for 98.75%, and at least one magnitude determination for 99.20% of the targets. The sources were collected from different optical and radio lists. We analyze the redshift, magnitude, and color distributions, their relationships, as well as their degree of completeness.

Complementary, the candidate sources enable to form an optical representation of the ICRS from first principles, namely, kinematically non-rotating with respect to the ensemble of distant extragalactic objects, aligned to the mean equator and dynamical equinox of J2000, and realized by a list of adopted coordinates of extragalactic sources.