TITLE:   GCN CIRCULAR
NUMBER:  45536
SUBJECT: GRB 260909A: Xinglong 2.16m optical upper limit
DATE:    26/09/09 15:59:21 GMT
FROM:    Yinuo Ma <mayn@bao.ac.cn>

Y. N. Ma, L. J. Chen, L. P. Xin, Y. L. Qiu, C. Wu, J. Wang, X. H. Han, P. P. Zhang, H. L. Li, J. Wang, J. Zheng, J. Y. Wei (NAOC), C. Plasse (HKU), A. Li (BNU) report on behalf of SVOM follow-up team:

We observed the field of GRB 260909A triggered by SVOM/ECLAIRs (Saccardi et al., GCN 45534) using the 2.16m telescope located at Xinglong observatory, China, equipped with the BFOSC camera. We obtained 3*60s frames in R-band, starting at 13:09:25 UT on 2026-09-09, about 1.86 hours after the trigger.

No uncatalogued source was detected in our stacked images compared to the Pan-STARRS catalog within the error box provided by SVOM/MXT (Saccardi et al., GCN 45534) down to 3-sigma upper limit of about 20.6 mag.

Our result is consistent with SVOM/C-GFT (Guan et al., GCN 45535).

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