As the Sun shows the well-known magnetic activity of eleven-year period, many other interesting observational features of the Sun have been examined in connection with the solar cycle. The diameter of the Sun is one of these interesting observable quantities. The apparent radius of the Sun has been observed regularly since 1985 with the Tokyo Photoelectric Meridian Circle (Tokyo PMC) at Mitaka. Here, we show the average value of the solar radii observed by us. We also show that the annual-mean values of the observed radii take the smallest value near the solar-cycle maximum, in 1989 and 1990, and the largest ones around the solar-cycle minimum, in 1986 and 1994. The average peak-to-peak shift of the annual-mean solar radius for the solar cycle is ΔR⊙/R⊙ ~ 1.2 × 10−4, which is close to the relative change of the frequency of the 5-minute p-mode solar oscillation within one solar cycle.

A classical astrolabe has been modernised and reconstructed into a new fully automatic instrument equipped with a CCD camera and allowing observations at two different zenith distances: 45° and 60°, respectively. The new instrument permits observations of objects fainter than those observable with the classical instrument. The work on the project is fairly advanced and regular observations are expected to begin in the nearest future. The paper reports results of the first observations and plans for the near future.

The projects LIGHT and MIRA are the space-borne and ground-based optical/Infrared-interferometer projects of the National Astronomical Observatory of Japan. The contents of each project are gradually developing, and the descriptions given below are the preliminary ones studied at the present time.

LIGHT (Light Interferometer satellite for the studies of Galactic Halo Tracers) is a scanning astrometric satellite for stellar and galactic astronomy planned to be launched between 2007 and 2010 by a M-V launcher of ISAS, Japan. Two sets of Fizeau-type 40cm-pupil interferometers with 1 m baseline are the basic structure of the satellite optics. The multi-color (U, B, V, R, I, and K) CCD arrays are planned to be used in the focal plane of the interferometer, optimized for detecting the precise locations of fringe patterns. LIGHT is expected to observe the parallaxes and proper motions of nearly a hundred million stars up to 18th visual (15thK-band) magnitude with the precision better than 0.1 milli-arcsecond (about 50 microarcsecond in V-band and 90 micro-arcsecond in K-band) in parallaxes and better than 0.1 milli-arcsecond per year in proper motions, as well as the precise photometric characteristics of the observed stars. Almost all of the giant and supergiant stars belonging to the disk and halo components of our Galaxy within 10 to 15 kpc from the sun will be observed by LIGHT to study the most fundamental structure and evolution of the Galaxy. LIGHT will become a precursor of a more sophisticated future astrometric interferometer satellite like GAIA (Lindegren and Perryman, 1996).

Results of minor planet observation programme that is made jointly by the Institute of Theoretical Astronomy and the Crimean Astrophysical Observatory during three decades with the Zeiss 40-cm double astrograph at Crimea are presented. Almost all permanently numbered minor planets were observed. A catalogue of astrometrical results obtained in the course of this survey contains more than 60 thousand minor planet positions. Many thousand unnumbered asteroids were discovered, 875 of which had received permanent numbers by June of 1996.

In the development of this survey programme we plan to use another Crimean telescope – the fast 64-cm telescope of Richter and Slevogt system. We intend to equip it with a CCD camera and use it for searching and observation of the Near Earth Asteroids. In the future this CCD-telescope must be a part of the national Russian network for Near Earth Asteroid (NEA) observations.