<Li> On January 5, 2015, NASA reported that CXO observed an X-ray flare 400 times brighter than usual, a record - breaker, from Sagittarius A *, a supermassive black hole in the center of the Milky Way galaxy . The unusual event may have been caused by the breaking apart of an asteroid falling into the black hole or by the entanglement of magnetic field lines within gas flowing into Sagittarius A *, according to astronomers . </Li> <Li> In September 2016, it was announced that Chandra had detected X-ray emissions from Pluto, the first detection of X-rays from a Kuiper belt object . Chandra had made the observations in 2014 and 2015, supporting the New Horizons spacecraft for its July 2015 encounter . </Li> <P> Unlike optical telescopes which possess simple aluminized parabolic surfaces (mirrors), X-ray telescopes generally use a Wolter telescope consisting of nested cylindrical paraboloid and hyperboloid surfaces coated with iridium or gold . X-ray photons would be absorbed by normal mirror surfaces, so mirrors with a low grazing angle are necessary to reflect them . Chandra uses four pairs of nested mirrors, together with their support structure, called the High Resolution Mirror Assembly (HRMA); the mirror substrate is 2 cm - thick glass, with the reflecting surface a 33 nm iridium coating, and the diameters are 65 cm, 87 cm, 99 cm and 123 cm . The thick substrate and particularly careful polishing allowed a very precise optical surface, which is responsible for Chandra's unmatched resolution: between 80% and 95% of the incoming X-ray energy is focused into a one - arcsecond circle . However, the thickness of the substrates limit the proportion of the aperture which is filled, leading to the low collecting area compared to XMM - Newton . </P> <P> Chandra's highly elliptical orbit allows it to observe continuously for up to 55 hours of its 65 - hour orbital period . At its furthest orbital point from Earth, Chandra is one of the most distant Earth - orbiting satellites . This orbit takes it beyond the geostationary satellites and beyond the outer Van Allen belt . </P>

What kind of telescope is the chandra observatory