Shanghai, Feb 2 (Xinhua) Astronomers from China, Japan and South Korea are building the world’s largest radio telescope array to study the Milky Way Galaxy and black holes as well as to determine the orbits of lunar probes such as China’s Chang’e-1.The array, called the East Asia Very Long Baseline Interferometry (VLBI) consortium, consists of 19 radio telescopes from China, Japan and South Korea that cover an area with a diameter of 6,000 km from northern Japan’s Hokkaido Island to western China’s Kunming and Urumqi regions.

The VLBI technology is widely used in radio astronomy. It combines the observations simultaneously made by several telescopes to expand the diameter and increase magnification.

Shen Zhiqiang, secretary general of the East Asia VLBI consortium committee (comprising the three countries), said the consortium has carried out experimental observations and frequent academic exchanges since the idea came into being in 2003.

One main task of the consortium is to improve the three-dimensional map of the Milky Way Galaxy obtained by Japan’s VERA (VLBI Exploration of Radio Astrometry), according to the project’s development plan.

Hideyuki Kobayashi, director of Japan’s Mizusawa VERA Observatory, told the Science Magazine in the US earlier that the consortium would help astronomers obtain high quality data on galactic structures.

Full-scale observations of the consortium are scheduled to start in 2010 and will connect at least 12 Japanese and four Chinese stations, in addition to three Korean stations that are under construction.

Shen said: “The actual number of telescopes included could change as the countries involved are building new ones like the 65-meter-diameter radio telescope being built in Shanghai.”

“In addition”, Shen said, also a researcher at the Shanghai Astronomical Observatory, “Chinese astronomers have made huge success in applying VLBI technology to determine the orbit of Chang’e-1, China’s first lunar probe.”

Shen’s research team also used VLBI to find the most convincing proof so far that there is a super-massive black hole at the centre of the Milky Way Galaxy.

Currently, China’s four telescopes participating in the consortium are still focusing on tracking the Chang’e-1 satellite, Shen said.

“But we are carrying out experimental observation tests as much as possible to prepare for the cooperation with Japan and South Korea,” he added.

The China VLBI Network announced Jan 20 that it successfully used the Internet to achieve high-speed data transmission called e-VLBI, an important direction for future VLBI technology development.

“The e-VLBI technology will play a vital role in China’s lunar and Mars explorations which have already been launched,” Shen said.

Meanwhile, Korean and Japanese astronomers are cooperating to build in Seoul a correlator to integrate large amounts of data into high-resolution images, a fundamental preparation for the consortium.

Radio telescopes differ from optical ones in that they use radio antennae to track and collect data from satellites and space probes.

The first radio antenna used to identify astronomical radio sources was built by Karl Guthe Jansky, an engineer with Bell Telephone Laboratories, in the early 1930s.