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| Name | Established | Location |
| Xiangfen Astronomical Observatory | 2100 B.C. | Xiangfen County, Linfen City, Shanxi Province, China |
| XMM-Newton | 1999 | Highly eccentric Earth orbit |
| Xujiahui Astronomical Observatory | 1872 | Shanghai, China |
Read more about this topic: List Of Astronomical Observatories