GCN Circular 40534
Subject
The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation
Date
2025-05-23T10:06:35Z (a day ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
H. Q. Cheng (NAO, CAS), Q. C. Shui (IHEP, CAS), Y. J. Song, Z. X. Ling (NAO, CAS) on behalf of the Einstein Probe (EP) team:
The on-ground analysis of EP-FXT observations shows that the EP-WXT trigger (ID: 01709176612) should be originated from a stellar flare associated with WISEA J122501.45-521614.6, but not Gaia DR3 6077506855610363648.
A better localization from the refined analysis is derived as R.A. = 186.2573 deg, Dec = -52.2713 deg (J2000), with an error radius of 10 arcsec (90% C.L.). This is spatially coincident with WISEA J122501.45-521614.6, with a separation of 3.4 arcsec. The result is consistent with the candidate counterpart identified in Swift/XRT observations (Evans et al., GCN #40528). Based on this positional agreement, we suggest that the EP-WXT trigger originates from WISEA J122501.45-521614.6. The previously suggested Young Stellar Object (YSO) candidate, Gaia DR3 6077506855610363648 (Song et al. GCN #40523), has been excluded as the counterpart due to its larger offset of 14.1 arcsec from the FXT error circle.