TITLE:   GCN CIRCULAR
NUMBER:  40957
SUBJECT: EP 250704a: BOOTES-5 optical detection
DATE:    25/07/04 18:00:16 GMT
FROM:    I. Perez-Garcia at Institute of Astrophysics of Andalusia <ipg@iaa.es>

I. Perez-Garcia (IAA-CSIC, Granada), Y.-D. Hu (GXU), E. J. Fernandez-Garcia, M. D. Caballero-Garcia, S.-Y. Wu, R. Sanchez-Ramirez, S. Guziy and A. J. Castro-Tirado (IAA-CSIC, Granada), I. M. Carrasco (SMA), M. Gritsevich (Univ. of Helsinki), C. Perez del Pulgar (Univ. of Malaga), S. Jeong (ADD, Daejeon), G. Garcia-Segura and D. Hiriart (IA-UNAM, Ensenada), D. R. Xiong (Yunnan Observatories of CAS, Kunming), and W. H. Lee (UNAM, Mexico DF), on behalf of a larger collaboration, report:

Following the detection of EP 250704a by the Einstein Probe (Li et al., GCN 40941), the 0.6m BOOTES-5/JGU robotic telescope at San Pedro Martir Observatory (Mexico) automatically responded to this high-energy event starting on July 4, 08:33:01 UT (i.e., 16 min after detection). Series of images in clear filter were gathered and we detect an optical source consistent with the one reported by Becerra et al. and Bjørn et al. (GCN 40942, 40945). Using GaiaDR3 Gmag as a reference, we measure an initial magnitude of 20.1 +/- 0.2. Further analysis of the additional images is ongoing.

We would like to thank the staff at San Pedro Martir Observatory for their excellent support.