China’s FAST radio telescope, a 500-metre dish set in a karst depression in Guizhou province, has compiled the world’s largest catalogue of neutral hydrogen beyond the Milky Way. This gas is the fuel that drives the formation of stars and galaxies.
The FAST All-Sky H I Survey (FASHI), whose second data batch was released this week, contains 156,411 extragalactic sources. That is nearly five times the number detected by the Arecibo Telescope in Puerto Rico, which is no longer operating.
Compared with the US ALFALFA survey, carried out at Arecibo from 2005 to 2012, FASHI covers about three times as much sky and detects smaller, fainter and more distant galaxies. The data, reported by a team led by the National Astronomical Observatories, is publicly available, allowing astronomers worldwide to study, for example, how the cosmic web formed.
