TITLE:   GCN CIRCULAR
NUMBER:  45903
SUBJECT: GRB 261011A: SVOM/C-GFT optical observations
DATE:    26/10/11 16:07:29 GMT
FROM:    SVOM_group <svomgroup@bao.ac.cn>

Y.Y. Shi(GXU), Z. Kang (CHO),S.J. Yin (GXU), C. Wu (NAOC), 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), Massimiliano Lincetto (CPPM), Damien Dornic (CPPM) report on behalf of the SVOM/C-GFT team:
 
We observed the field of GRB 261011A detected by SVOM/ECLAIRs (Huang et al., GCN 45895) with LATIOS on SVOM/C-GFT. Observations started at 2026-10-11T13:52:56 UTC, ~3.87 min after the trigger. 
 
 
The optical candidate (Cenko et al., GCN 45896; O'Neill et al., GCN 45897; Fu et al., GCN 45898; Izzo et al., GCN 45899; Wu et al., GCN 45900; Yin et al., GCN 45901) was detected in our images of band i. The magnitude is:
|[date-obs(mid-time)] | Mid_t-T0(min) | exposure time (s) | band | mag (AB) | mag_err|
|--------------------|--------------|-------------------|------|----------|--------|
|2026-10-11T13:53:01 | 3.95 | 10s | i | 15.25 | +/- 0.06 |


The photometry was calibrated against DESI Legacy Imaging Surveys DR10 catalogue and no correction for Galactic dust extinction was applied.
  
We thank the observation assistants B.-W. Li and H.-X. Xue 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.