GCN Circular 40943
Subject
EP250702a: WFST optical observations
Event
Date
2025-07-04T10:42:26Z (10 days ago)
From
ylhua@pmo.ac.cn
Via
Web form
Yan-Long Hua, Jin-Jun Geng, Xue-Feng Wu, Hui Sun, Ye Li, Zhi-Ping Jin, Tian-Rui Sun, Yi-Fang Liang, Ding-Fang Hu, Yuan-Tai Yang, Ji-An Jiang report on behalf of the WFST team:
Following the detection of EP250702a by Einstein Probe (Cheng et al., GCN 40906, 40917), Fermi/GBM (Fermi GBM Team, GCNs 40883, 40885, 40886, 40890), Swift/BAT (via the GUANO system; DeLaunay et al., GCN 40903), and Konus/Wind (Frederiks et al., GCN 40914), all likely originating from the same astrophysical source (Neights et al., GCN 40891), the VLT (A. Martin-Carrillo et al., GCN 40924) identified a bright source that is absent in archival H- and K-band images from VISTA/VHS and UKIDSS.
We performed follow-up observations using the Wide Field Survey Telescope (WFST Collaboration; arXiv:2306.07590) at the Lenghu Astronomical Observation Base in Qinghai Province, China. Observations in the r-band began at 2025-07-03T17:26:10 UTC, approximately 28.29 hours after the trigger. The limiting magnitude of the stacked image reaches 22.19 (AB), and no unknown transient sources were detected in the region corresponding to the VLT observation.
We thank the WFST staff for supporting these observations.