GCN Circular 39439

S.-Y. Wu, I. Perez-Garcia, E. Fernandez-Garcia,  M. D. Caballero-Garcia, G. Garcia-Segura, S. Guziy, R. Sanchez-Ramirez and A. J. Castro-Tirado (IAA-CSIC, Granada), C. Perez del Pulgar (Univ. de Malaga), M. Gritsevich (Univ. of Helsinki),  Y.-D. Hu (GXU), and D. R. Xiong, J. M. Bai, Y. F. Fan, C. J. Wang, Y. X. Xin, X. H. Zhao, J. R. Mao, B. K. Lun, K. Ye (Yunnan Observatories/CAS, Kunming) on behalf of a larger collaboration, report:

Following the detection of EP250223a by EP/WXT (Lian et al. GCNC 39429), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) automatically responded to this burst starting on Feb. 23, 15:16:38 UT (~12 min after trigger). At the position of the EP/FXT X-ray source (also recorded by Swift/XRT, Kennea et al. GCNC 39437), an optical counterpart is detected, for which we measure a magnitude of 18.4 +/- 0.1 (60s, clear filter, comparable with Gmag of Gaia DR3), which also consistent with the object reported by NOT at a later stage (Hauptmann et al. GCNC 39426, Levan et al. GCNC 39438). Further analysis of the additional images is ongoing.

We thank the staff at Lijiang observatory for their excellent support.