<Tr> <Th> LETG </Th> <Td> Low Energy Transmission Grating </Td> </Tr> <Tr> <Td_colspan="2"> Great Observatories ← Compton Spitzer → </Td> </Tr> <P> The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship - class space observatory launched on STS - 93 by NASA on July 23, 1999 . Chandra is sensitive to X-ray sources 100 times fainter than any previous X-ray telescope, enabled by the high angular resolution of its mirrors . Since the Earth's atmosphere absorbs the vast majority of X-rays, they are not detectable from Earth - based telescopes; therefore space - based telescopes are required to make these observations . Chandra is an Earth satellite in a 64 - hour orbit, and its mission is ongoing as of 2018 . </P> <P> Chandra is one of the Great Observatories, along with the Hubble Space Telescope, Compton Gamma Ray Observatory (1991--2000), and the Spitzer Space Telescope . The telescope is named after the Nobel Prize - winning Indian - American astrophysicist Subrahmanyan Chandrasekhar . Its mission is similar to that of ESA's XMM - Newton spacecraft, also launched in 1999 . </P>

Where is the chandra x ray telescope located