The methods for linking a fundamental stellar reference coordinate system to a VLBI extragalactic radio source reference system are briefly discussed and a new connection is given in this paper. The effect of the structure of a radio source and the relation between the two systems arc also considered.

In this paper, the possibility of detecting the plate motion by means of the LLR data now available is discussed, and the annual variations in the baseline lengths are calculated to research the plate motion by using the data obtained at three LLR stations from 1983 to 1988. The authors recognize that it is not long since the world's LLR network was set up, the observed lunar distance has been accurate within 5 cm since 1986 and the available LLR data are not enough to be used to detect the plate motion. But the UT1-UTC in the earth rotation parameters can be calculated by means of the LLR data obtained at a single station. The sequences of the solutions of the UT1-UTC obtained by using the LLR data of the stations are compared with those of the synthetic solutions issued by BIH(or IERS from 1988), and then the longitudinal motions of the stations are indirectly detected, within an accuracy of the order of centimeter. The results are in accordance with the predicted values obtained according to the AM_1-2 plate motion model.

The statistical analyses are made on the basis of the observations of the SPA of LF skywaves obtained at the Yunnan Observatory and of the X-ray data published by 《SGD》. It can be seen from the analysed results that the SPA of LF skywaves is correlated well with the solar X-ray bursts. Some useful results are also derived from the analyses.

The falling motin of the matter within the loop system is studied in this paper under the joint action of the solar gravity, the gradient of the magnetic pressure of the dipole and the gradient force of the gas pressure and the two-dimensional sight-line velocity field of the loop system is calculated by use of the numerical method on the assumption that one has an isothermic and quasi-closed loop system. The relative physical parameters within the system and their distribution are derived from the fitting of the theoretically calculated results of the velocity field with the observed results. The calculated results indicate that the density and the intensity of the magnetic field within the loop system have an obvious influence on the falling motion of matter, but the influence of the temperature on the falling motion is relatively small.

A joint radio observation of the annular solar eclipse of 1987 September 23 at multiple wavelengths, organized by the Bureau of Mathematics, Physics and Chemistry of the Chinese Academy of Sciences, was carried out in China and a wealth of data were obtained. After the observation the joint analyses and studies of the data, were made and some jignificant results have been obtained. The main points of the method of the data analysis, processing and:iudy are introduced in this present article.

In this paper, the acceleration of a neutral test particle in the static CM field is discussed and the results show that a ring object will be produced from the collapse of the compact object with charges and magnetic moments when e²<<α²p².

In this paper, a new method, i. e. the approximate lambda operator methcd introduced by Werner(1986) is proposed in detail for calculating the Non-LTE stellar atmospheric model and for treating the blanketing effect of the Non-LTE line effectively, on the basis of the analysis of the fact that the completely linearized method can not be used to deal with the blanketing effect of the Non-LTE line well. And the advantages, disadvantages and possible application of the method are also analysed and discussed.

The effects of the gravity bending of both the collimator and camera of the Cassegrain spcctrograph of the 1-m telescope at the Yunnan Observatory are analysed theoretically, Forty-five photographs with the comparison spectrum at as many pointings of the telescope are taken to measure the line shift caused by the gravity bending. The measured results show that the effects of the gravity bending surely exist and the line lift is of the order of magnitude of a micron. The measured data are in accordance with the theoretical calculations. Some methods are also discussed for offsetting the effects of the gravity bending on the mea surcment of wavelengths, line profiles and spectral resolving powers.

During the spectral observation made with the CCD system on the camera(f=1900mm) of the Coude' spectrograph attached to the 1-m telescope at the Yunnan Observatory, the selection and the calculation of some important parameters, such as the wavelength photographed once, the dispersion, the rotation angle of the grating and the filters, etc., and some problems for attention arc presented in this paper.

The new automatic operation system for time and frequency services is capable of making timekeeping, measuring time, handling data and correcting the rvbidium frequency standard automatically. Its structure and main performance are described in this paper.

The anti-backlash of the 10-meter radio telescope at the Yunnan Observatory is analyzed and discussed in detail. The actually adoptable plan for the elimination of the gear backlash, i. c. the plan of the torsion bar antibacklash, is expounded and proved, and it has been put into effect on the antenna structure. The measured results indicate that the final gear backlash is eliminated and the desired results are achieved.

This paper briefly reports on the basic principle, application and test results of the speed regulator system of the DC motor tachogenerator set for the automatic control of the antenna of the 10-m radio telescope at the Yunnan Observatory.

The emisions of the radiotion of the radio microwaves during the eruption of the solar flares which occurred on May 3 and August 17, respectively, 1989, are analyzed and some of the very interesting results are also given in this present article.