TITLE: GCN CIRCULAR NUMBER: 39053 SUBJECT: GRB 250127A: EP-FXT afterglow detection DATE: 25/01/28 11:49:14 GMT FROM: EP Team at NAOC/CAS ep_ta@bao.ac.cn
Y.-H. I. Yin (NJU), Y. L. Wang, H. N. Yang, H. Y. Liu (NAO, CAS), Z. Y. Liu, M. Q. Huang (USTC), Z. X. Ling, Y. Liu (NAO, CAS), B. Cordier (CEA) on behalf of the Einstein Probe team:
We performed a follow-up observation of GRB 250127A (SVOM, Wu et al., GCN 39041) with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation started at 2025-01-27 11:29:09 (UTC) with ~ 2.4 ks of exposure in total.
An uncatalogued X-ray source is detected by both modules of FXT at the position of R. A. = 169.6284 deg, DEC = 3.3508 deg (J2000) with an uncertainty of 10 arcsec (90% C. L.), which is 2.38 arcmin away from the SVOM position (Wu et al., GCN 39041). This position is also consistent with the location of Swift/XRT Source 2 (P. A. Evans, GCN 39044). The average FXT 0.5-10 keV spectrum can be fitted with an absorbed power law with a fixed Galactic equivalent hydrogen column density of 4.52 x 10^20 cm^-2 and a photon index of 1.79 (-0.92/+0.92). The derived average unabsorbed 0.5-10 keV flux is 1.30 (-0.68/+1.44) x 10^(-13) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters.
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). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES.
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