TITLE: GCN CIRCULAR NUMBER: 39037 SUBJECT: EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection DATE: 25/01/26 08:05:59 GMT FROM: EP Team at NAOC/CAS ep_ta@bao.ac.cn

R.-Z. Li, J. Mao (YNAO, CAS), H. Sun, Y. Liu (NAO, CAS) and B. Zhang (UNLV) report on behalf of the Einstein Probe team:

We re-analysed the WXT spectrum extracted from T0 to T0 + 2200 seconds (Li et al., GCN 38861). The average 0.5-4 keV WXT spectrum can be fitted by an absorbed power law model with a photon index of 3.03 (-1.52, +2.23) (with a fixed Galactic equivalent hydrogen column density of 1.6 x 10^20 cm^-2). The derived upper limit of the intrinsic column density is nH < 1.18 x 10^22 cm^-2 when the redshift is fixed at 0.176 (Zhu et al., GCN 38908). The derived average unabsorbed 0.5-4 keV flux is 6.38 (-3.00, +22.52) x 10^-11 erg/s/cm^2. Note that the presence of large uncertainties in the spectral parameters.

Due to a mistake in spectrum extraction, an incorrect photon index of ~ 1.4 was reported in our preliminary GCN circular (Li et al., GCN 38861). We apologize for any confusion this may have caused.

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