The Radio Astronomy and VLBI research group from Yunnan Observatories of the Chinese Academy of Sciences (CAS) operated the 40-meter radio telescope on September 17, 2019, to participate in broadband network transmission and real-time correlation observations of the European Very Long Baseline Interferometry (VLBI) network, also called eVLBI observation.

This observation successfully participated in the previous test observations and the follow-up scientific observations, and transmitted a large amount of long-baseline data to Chinese and foreign astronomers.

VLBI is an astronomical technique that combines radio signals from radio telescopes around the world for positioning and high-resolution imaging of deep space celestial objects and distant black holes.

Under the support of ZHANG Hongyu from the Computer Network and Information Center (CNIC) of CAS and YANG Yuecheng from Yunnan Observatories of CAS from May to early September 2019, the Radio Astronomy and VLBI research group have completed installation of the optical cable equipment and upgraded network equipment, and then tested the network.

Compared with the traditional VLBI observation methods which are disk recording and correlation processing after several weeks, the eVLBI observation reduces a lot of time for astronomers to wait for data correlation, which is extremely beneficial to the structural observation of various temporary sources with an outbreak duration of several days. It can promote the development of time domain astronomy.

In this eVLBI observation, the Kunming station of Yunnan Observatories transmitted the data to the correlation center in the Netherlands with a stable rate of about 1 gigabit per second via CNIC in Beijing.

The 40-meter telescope undertakes the VLBI and data transmission work of the China's Lunar Exploration Program. It is also an important station of many international VLBI organizations, and often participates in international VLBI joint observations.

The success of this eVLBI observation greatly improved the ability of the Kunming 40-meter telescope to perform real-time observations, and laid the foundation for a higher-speed real-time observation of 2-6 Gbps (2-6 gigabits per second).

In the future, the Radio Astronomy and VLBI research Group will continue to upgrade the network hardware, to achieve super high-speed network real-time observation as soon as possible.