TITLE: GCN CIRCULAR NUMBER: 42511 SUBJECT: GRB 251026A/EP251026a: EP-FXT follow-up observation DATE: 25/10/29 13:22:19 GMT FROM: EP Team at NAOC/CAS ep_ta@bao.ac.cn
A. Li (BNU), J. H. Wu (GZHU), H. Q. Cheng and H. Sun (NAOC) on behalf of the Einstein Probe (EP) team:
EP-FXT performed two follow-up observations of GRB 251026A/EP251026a (GCN 42454) at 2025-10-27T09:41:08 and 2025-10-28T01:39:45 (UTC), respectively, about 25 and 41 hours after the ECLAIRs' trigger, with an exposure time of 2.7 and 6.0 ks. No source was detected in the first observation. The second observation detected a weak uncatalogued source within the WXT error circle at R.A. = 72.6573, DEC = 51.7653 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic). Based on the spectral fitting result, we got a powerlaw spectrum with the absorption fixed at the Galactic value of 3.77x10^21 cm^-2 and the photon index of 2.5, the flux in 0.5-10 keV is derived to be approximately 5.4x10^-14 erg/s/cm2 from the FXT count rate.
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).
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