TITLE:   GCN CIRCULAR
NUMBER:  46157
SUBJECT: GRB 261103A: SVOM/C-GFT optical upper limit
DATE:    26/11/05 13:48:57 GMT
FROM:    SVOM_group <svomgroup@bao.ac.cn>

S.J. Yin(GXU), Z. Kang (CHO), C. Wu , L.P. Xin, X.H. Han, P.P. Zhang, X.M. Lu (NAOC), Z.W. Li, Y. Lv (CHO), R.S. Zhang, Y.J. Xiao, Y.L. Qiu, J. Wang, J.S. Deng, L. Huang, J.Y. Wei (NAOC), Y.X. Guan, Y.Y. Shi(GXU), Y.-H.Cheng (YNU), W.-L.Zhang (PMO) report on behalf of the SVOM/C-GFT team:
 
We observed the field of GRB 261103A detected by SVOM/ECLAIRs  (Brunet et al., GCN 46137) with LATIOS on SVOM/C-GFT. Observations started at 2026-11-03T 11:17:01.4 UTC, ~ 4.43 hr after the trigger. 
 
We obtained follow-up imaging in i bands. After preliminary analysis, no credible candidate was detected within the error box provided by SVOM/ECLAIRs (Brunet et al., GCN 46137) in our images. We measure the following upper limit calibrated against the Pan-STARRS DR1 catalog, and not corrected for Galactic extinction:
 
i > 20.1AB (3-sigma, mid-time 4.58 hr after the trigger).
 
 
We thank the observation assistants Y.-H. Hao and C.-L. Guo  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 arcmin x 21 arcmin 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.