TITLE: GCN CIRCULAR NUMBER: 42441 SUBJECT: GRB 251025A (sb25102501): stellar flare confirmed DATE: 25/10/25 17:15:53 GMT FROM: SVOM_group svomgroup@bao.ac.cn
Zhe Kang (CHO), Chao WU (NAOC), Liping Xin(NAOC), Xuhui Han(NAOC), Pinpin Zhang (NAOC), Xiaomeng Lu (NAOC), Zhenwei Li (CHO), You Lv (CHO), Ruosong Zhang (NAOC), Yujie Xiao(NAOC), Yulei Qiu(NAOC), Jing Wang (NAOC), Jinsong Deng(NAOC), Lei Huang(NAOC), Jianyan Wei (NAOC), Z.M. Wang (BNU), W.J. Tan (IHEP) report on behalf of the SVOM/C-GFT team:
We observed the field of GRB 251025A (sb25102501) detected by SVOM/ECLAIRs (wang et al., GCN 42432) with LATIOS on SVOM/C-GFT. Observations started at 2025-10-25T09:36:54 UTC, ~92 seconds after the trigger.
A sequence of images in the g, r, and i bands was obtained. The likely flaring star RX J2350.0+2659, reported by Li et al. (GCN 42435), is clearly detected. The source exhibited a fade in the i band from 9.68 to 11.38 mag over ~40 min, starting around T0+93 sec. Our observations confirm that this is a stellar flare.
We thank the observation assistants Hongxu Xuan and Bowen Li at Jilin observatory for their excellent support.
The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcsec x 21 arcsec FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching.
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