The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a NASA space telescope launched aboard the Space Shuttle Columbia during STS-93 by NASA on July 23, 1999. It is the third of the Great Observatories (after Hubble and Compton) to be launched. Its mission is still ongoing as of 2021
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