TITLE:   GCN CIRCULAR
NUMBER:  42140
SUBJECT: GRB 251006B/EP251006a: EP-FXT follow-up observation
DATE:    25/10/07 13:03:20 GMT
FROM:    EP Team at NAOC/CAS <ep_ta@bao.ac.cn>

Y.-H. I. Yin (HKU), M. H. Zhang, T. Y. Liu, H. Y. Ren and Z. X. Ling (NAO, CAS) on behalf of the Einstein Probe (EP) team:

EP-FXT performed a follow-up observation of GRB 251006B/EP251006a (GCN 42131, GCN 42137, GCN 42139) at 2025-10-07T06:50:56 (UTC), about 11 hours after the WXT detection, with an exposure time of 2.7 ks. The source was also followed by several optical telescopes (GCN 42133, GCN 42138). Two uncatalogued sources were detected within the WXT error circle. Preliminary analyses on these sources are automatically conducted, and the details are listed as follows.

Source 1: EPF_J024205.3-055701
RA (J2000): 40.5219
Dec (J2000): -5.9501
Flux: 3.25 x 10^-13 erg/s/cm^2 (observed, 0.5-10 keV)
Flux_err: 9.45 x 10^-14 erg/s/cm^2 (1 sigma)

Source 2: EPF_J024204.7-060206
RA (J2000): 40.5194
Dec (J2000): -6.0350
Flux: 3.52 x 10^-12 erg/s/cm^2 (observed, 0.5-10 keV)
Flux_err: 4.30 x 10^-13 erg/s/cm^2 (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).