GCN Circular 42643
Subject
GRB 251111A: EP-FXT counterpart detection
Event
Date
2025-11-11T13:12:22Z (2 days ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
Y.H. Cheng (SWIFAR,YNU), Z. M. Wang (BNU), Y. J. Zhang (THU), C. L. Guo, J. W. Hu, Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team:
EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 251111A (SVOM/sb25111101, Cheng et al., GCN #42637) at 2025-11-11 06:06:55 (UTC), about 0.93 hours after the SVOM/ECLAIRs trigger, with an exposure time of 1939 s. One uncatalogued source is detected within the ECLAIRs error circle, and the source is spatially consistent with the counterpart reported in optical band (López-Cámara et al., GCN #42638; Wu et al., GCN #42639, Zheng et al., GCN #42640, Wu et al., GCN #42641). Preliminary analysis on this source is automatically conducted, and the details are listed as follows.
Source 1 ：EPF_J020926.9+051342
RA (J2000): 32.362
Dec (J2000): 5.228
Flux: 1.24 x 10^-12 erg/s/cm2 (observed, 0.5-10 keV)
Flux_err: 3.53 x 10^-13 erg/s/cm2 (1 sigma)
The position uncertainty of the source is about 10 arcsec in radius (90% C.L. statistical and systematic).
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).