TITLE: GCN CIRCULAR NUMBER: 43201 SUBJECT: EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient DATE: 25/12/23 03:35:23 GMT FROM: EP Team at NAOC/CAS <ep_ta@bao.ac.cn> C.-L. Guo (NAO, CAS), R. Shi (PMO, CAS), Q.-J. Huang (PMO,CAS), X. Mao (NAO, CAS), and Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP251222b. The transient triggered EP-WXT (ID: 01709250454) at 2025-12-22 17:05:34 (UTC). The WXT position of the source is R.A. = 77.207 deg, DEC = -7.208 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). EP251222b is located 0.8 arcmin away from GRB 251222A (GCN 43189), and the trigger time is differ by only 12 seconds. Thus EP251222b is possibly associated with GRB 251222A. Further information will be updated when the telemetry data are received. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/43201. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...