A 4-m reflector with a mirror of liquid mercury being built at Devasthal, India, by an international consortium of organizations from Belgium, Canada, India, and Poland. The mirror consists of a dish containing a thin layer of mercury spun at 7.5 rev/min to create a parabolic surface. The telescope will scan a strip of sky half a degree wide at the zenith as the Earth rotates.

http://www.ilmt.ulg.ac.be Official telescope website.