Terzan 1

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Terzan 1, also known as ESO 455-23 and Terzan 1966, is a heavily obscured globular cluster in the Scorpius constellation. It lies about 21,800 light-years from Earth and only about 4,200 light-years from the center of the Milky Way, making it the closest known globular cluster to the Galactic center. Discovered by French astronomer Agop Terzan in the 1960s–70s, Terzan 1 is part of the Milky Way. The cluster is also an X-ray source; in 1980, X-ray bursts were detected there, and later the X-ray source X1732-304 was found within Terzan 1 using Spacelab 2 and ESA's EXOSAT missions. It has several alternate names, including Cl Haute-Provence 2 and GCl 69.