On March 11th, the 26-meter radio telescope at the Nanshan Observatory of the Chinese Academy of Sciences (referred to as the Nanshan Observatory) participated in a 4Gbps broadband, high-data-rate VLBI joint observation organized by the European VLBI Network (EVN). Real-time data processing indicated successful acquisition of interference fringes.
According to the Chinese Science Bulletin, it was the first time that the Nanshan 26-meter radio telescope achieved 4Gbps VLBI observation. Compared to 2Gbps observations, theoretically, the signal-to-noise ratio can be increased by approximately 1.4 times. This achievement demonstrates that the Nanshan 26-meter radio telescope has the capability for ultra-broadband, high-data-rate VLBI observations, placing it at the forefront internationally. It marks another significant milestone in the technical upgrade and astronomical observation service enhancement of the telescope.
VLBI is a technology that combines radio telescopes thousands to tens of thousands of kilometers apart to simultaneously observe the same target source, effectively creating a giant telescope. Compared to single-antenna observations, VLBI offers much higher spatial resolution, allowing for detailed structures of distant radio sources with sub-milliarcsecond or even microarcsecond resolution, as well as more precise positional information. The first-ever image of the black hole shadow in M87, captured by humans, was achieved using VLBI technology. Additionally, VLBI plays an indispensable role in establishing high-precision international celestial reference frames.
The successful 4Gbps VLBI joint observation by the Nanshan Observatory employed digital backends DBBC2+FleXbuff for data sampling and recording, with a total of 16 BBC channels, each channel having a bandwidth of 32MHz and 2-bit sampling, achieving a data rate of 4096 Mbps.
Located in the heartland of the Eurasian continent, the Nanshan 26-meter radio telescope is an important member of the European VLBI Network (EVN) and the International VLBI Service for Geodesy and Astrometry (IVS). It serves approximately 750 hours per year during three EVN observation sessions, with this observation being the first task of the 2024 EVN observation season.
