Two Microsoft billionaires gave $30 million on 3 January to build the Large Synoptic Survey Telescope (LSST), a proposed $389-million instrument that would make time-lapse movies of the sky, which astronomers could scour for brief celestial events.

Bill Gates gave $10 million to the project, which has 23 partners. The foundation set up by ex-Microsoft executive and space tourist Charles Simonyi gave $20 million.

When complete in 2014, the 8.4-metre mirror will focus light onto a 3.2-billion-pixel digital camera, taking 15-second exposures of huge swaths of the sky, scanning the entire sky every three or four nights. Planned for the mountains of northern Chile, scientists could use the LSST to watch supernovae, active galactic centres and near-Earth asteroids.