GCN Circular 40259

I. Perez-Garcia, A. J. Castro-Tirado, E. Fernandez-Garcia, S.-Y. Wu, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy (IAA-CSIC), C. Perez del Pulgar (Univ. de Malaga), G. Garcia-Segura (Inst. de Astronomia, UNAM), M. Gritsevich (Univ. of Helsinki), D. R. Xiong (Yunnan Observatories of CAS), Y.-D. Hu (GuangXi Univ.), B.-B. Zhang (Nanjing Univ.) and A. Maury (Space, San Pedro de Atacama), on behalf of a larger collaboration, report:

Following the detection of EP 250427a by EP (Wang et al., GCNC 40257), the 0.6m BOOTES-7 robotic telescope at San Pedro de Atacama (Chile) automatically responded to this fast X-ray transient starting on Apr 27, 07:21:09 UT (i.e., ~4 hours after detection). In the first 60 s exposure image, an uncatalogued source is detected at the EP-FXT position, at coordinates (J2000): RA = 18:29:05.7, Dec =  +07:33:46.5, with a preliminary magnitude of 18.1 +/- 0.08 mag (clear filter) using GaiaDR3 Gmag as a reference, which we propose to be the optical afterglow to EP 250427a. Spectroscopic observations are encouraged.

We thank the staff at San Pedro de Atacama Celestial Observations for their excellent support.