East Asia builds world's largest radio telescope network

by Chinese media Writer Wang Aihua

SHANGHAI, Feb.1 (Chinese media) -- East Asian astronomers

are building the world's largest radio telescope array to see the deep into the

galaxy and black holes and more accurately 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 the Republic of Korea (ROK) that cover an area with a diameter of

6,000 kilometers from northern Japan's Hokkaido to western China's Kunming and

Urumqi.

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, told Chinese media Sunday, 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 U.S. 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 which will connect at least 12 Japanese and four

Chinese stations, in addition to three Korean ones 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 center

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 ROK," he

said.

The China VLBI Network announced on 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.