TITLE:   GCN CIRCULAR
NUMBER:  39805
SUBJECT: EP250321a: BOOTES-5/JGT optical afterglow detection
DATE:    25/03/21 08:52:33 GMT
FROM:    ipg@iaa.es

I. Perez-Garcia, E. J. Fernandez-Garcia, G. Garcia-Segura, M. D. Caballero-Garcia, S.-Y. Wu, R. Sanchez-Ramirez, S. Guziy and A. J. Castro-Tirado (IAA-CSIC, Granada), M. Gritsevich (Univ. of Helsinki), C. Perez del Pulgar, A. Castellon (Univ. de Malaga), Y.-D. Hu (INAF-OAB, Brera), S. Jeong (ADD, Daejeon) and D. Hiriart and W. H. Lee (UNAM), on behalf of a larger collaboration, report:

Following the detection of EP250321a by Einstein Probe (Hu et al. GCNC 39800), the BOOTES-5/JG robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically responded to this X-ray transient starting on 2025-03-21 07:27:36 UT (23 min after notification). Series of images in clear filter were gathered and we detect and uncatalogud source at RA, Dec = 11:57:03.0, +17:21:46.2 (179.26263, 17.36283) within the WXT region, for which we measure a magnitude of 19.6 +- 0.1, consistent with Fu et al. (GCNC 39804). Further analysis of the additional images is ongoing.

We thank the staff at Observatorio Astronomico Nacional in San Pedro Martir for their excellent support.