TITLE: GCN CIRCULAR NUMBER: 44387 SUBJECT: GRB 260421B: EP-FXT follow-up observation DATE: 26/04/22 02:42:41 GMT FROM: EP Team at NAOC/CAS <ep_ta@bao.ac.cn> B. T. Wang (YNAO, CAS), J. P. Chen (SYSU), D. Y. Li, and W. D. Zhang (NAO, CAS) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 260421B (SVOM/sb26042105; Zhao et al., GCN 44362), also triggered by Fermi-GBM (Fermi GBM team, GCN 44360; Preis & Greiner, GCN 44361; Mukherjee et al., GCN 44382), starting at 2026-04-21T06:08:31UTC, approximately 1.9 hours after the SVOM trigger, with a total exposure time of 5994 s. One uncataloged source is detected within the ECLAIRs error circle, which is spatially consistent with the optical counterpart (He et al., GCN 44363; Sanchez-Alvarez, GCN 44364; Turpin et al., GCN 44365; Wu et al., GCN 44366, Li et al., GCN 44377; Pérez-Fournon et al., GCN 44383) at a redshift of z=2.115 (Schneider et al., GCN 44368). Preliminary analysis on this source is automatically conducted, and the details are listed as follows. EPF_J124000.4-174426 RA (J2000): 190.0018 Dec (J2000): -17.74055 Flux: 1.26e-11 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 6.27e-13 erg/s/cm2 (1 sigma) 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/44387. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...