TITLE:   GCN CIRCULAR
NUMBER:  38764
SUBJECT: GRB 250101A: BOOTES-4/MET optical afterglow detection
DATE:    25/01/01 22:09:03 GMT
FROM:    Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct@iaa.es>

Y.-D. Hu (INAF-OAB, Brera), E. Fernandez-Garcia, I. Perez-Garcia, M. D. Caballero-Garcia, G. Garcia-Segura, S. Guziy, R. Sanchez-Ramirez,  S.-Y. Wu and A. J. Castro-Tirado (IAA-CSIC, Granada), C. Perez del Pulgar, A. Castellon, I. M. Carrasco (Univ. de Malaga), M. Gritsevich (Univ. of Helsinki) 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 GRB 250101A by Swift (Page et al. GCNC 38752), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) automatically responded to this burst starting on Jan. 1, 13:26:58 UT (~248 s after trigger). Series of images in clear filter were gathered and the optical afterglow was detected within the enhanced Swift/XRT position (Goad et al. GCNC 38761), for which we measure a magnitude of 17.7 +- 0.3 on the first 5 s exposure image, which is consistent with the reported detections by UVOT (Page et al. GCNC 38752), GMG (Li et al. GCNC 38753), GIT (Mohan et al. GCNC 38754), Nanshan (Zhu et al. GCNC 38755), MASTER (Lipnov et al. GCNC 38756), C-GFT (Wu et al. GCNC 38758), Xinglong-2.16m (Zhu et al. GCNC 38759), SAO (Moskvitin et al. GCNC 38762) and AKO (Odeh et al. GCNC 38763). Further analysis of the additional images is ongoing.

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