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The first Chinees Mars Probe, Yinghuo-1, is planned to launch in October 2009, together with the Russia Phobos-Grunt landing mission. YH-1 will explore the space weather of the Mars, and test the the deep space communication and navigation techniques. Difference from common deep space probe, the astronomical Very Long Baseline Interferometry (VLBI), open loop tracking method, like DOR/DOR, seam beam VLBI and 1-way Doppler, will be used to determine the s/c orbit and position.

An outline of the astrometric series of the ERP of their accuracy and of the results obtained from analyses of these data are given in the paper. Presently known systematic differences between the astrometric ERP series and those determined by VLBI and Lageos ranging techniques are discussed. Some geophysical applications of latitude and longitude variations determined by astrometric techniques are mentioned.

This paper briefly introduces the current status of the Chinese VLBI Network (CVN) Project and its astrometric and geodetic goals.

30 Observational series which include the ERP component, latitude or time results of 15 main networks using six techniques (Ast, Doppler, SLR, LLR, VLBI and CEI) have been reduced to give a combined determination of the ERP for the period 1980 Jan 1 – 1984 October 31. The systematic error of each series is modeled by a constant plus a drift, and these are adjusted together with the ERP unknowns. The accuracies and systematic errors of the 15 networks so found are also given.

In this paper a periodogram analysis is applied to the 1820–1970 data of Earth's rotation in a search for hidden periods ranging from a few years to several decades. 12 periods are found and their combination matches well the observed variation over these 150 years. Most of the periods are very close to the periods of the sunspots, the Moon and the planets. The extrapolated curve remains in good fit with data observed in 1972. The results may be useful in further investigations on the underlying mechanisms and in forecasting future trend in the variation of the Earth's rotation.

During the period, work on the problem of the Earth’s rotation has continued to expand and increase its scope. The total number of institutions engaged in the determination of the Earth’s rotation parameters (ERP) by different techniques has been increased significantly. The rotation of the Earth is currently measured by classical astrometry, Doppler and laser satellite tracking, laser ranging of the Moon, and radio interferometry. Several long time series of the ERP are available from most of these techniques, in particular, those made during the Main Campaign of the MERIT project. The various series have been intercompared and their stability, in the time frame of years to days, has been estimated for the purposes of establishing a new conventional terrestrial reference system (COTES). On the other hand, the difficulties of maintaining a regular operation for laser ranging to the Moon (LLR) have been recognized. It resulted in the proposal to organize an one-month campaign of observations in 1985 in order to complement the COTES collocation program and to allow additional intercomparisons with other techniques.

The space age and modern technology have opened a new era for astrometry. A great amount of modern, precise astrometric data and approaches is urgently needed not only for astrophysics but also for Earth Science research. The Astrometric Community looks forward to establishing a precisely specified uniform celestial frame of reference for all purposes, which will link the bright stars, faint stars, and galaxies, down to the remote radio sources, and to establish a terrestrial frame of reference as well as to specify a precise transformation between these two frames. Effective international cooperation is the goal of all astrometrists. The Chinese astronomers are ready to join and play an active part in this cooperation.

This paper is based on optical observations of 85 instruments (Table 1-a) from January to October 1980. The accuracies of all instruments, 62 for time and 54 for latitude, are shown in Table 1-b, in which:–the roughness ε1i of daily observations is defined by the standard deviation of the observation values of the i-th instrument with respect to the smoothed values of themselves;–the ε2i is the standard deviation of mean observation values during every 0.05 year with respect to the global reference system.The average accuracy of each type of instrument is given in Table 2, regional averages are given in Table 3.These tables show that errors in time observations are greater, generally speaking, than those in latitude, and low frequency errors are greater than high frequency ones in time observations.

Before we introduce the intercomparison of celestial reference frames, let us first examine the structure of a reference frame, what are the causes of difference between them and how they can be compared.

The present report covers the period 1 February 1985 to 30 November 1987. During this period a total of 23 travel grants were awarded as follows