TITLE:   GCN CIRCULAR
NUMBER:  46252
SUBJECT: GRB 261113A: SVOM/VT optical observation from VHF data
DATE:    26/11/13 17:09:48 GMT
FROM:    SVOM_group <svomgroup@bao.ac.cn>


C. Wu, L. P. Xin, Y. L. Qiu (NAOC), J. T. Palmerio, A. Saccardi (CEA/Irfu), E. Arrigoni (INAF/IASF-Milano), S. Bisero (CEA/Irfu)  
on behalf of the SVOM/VT team.


After the trigger by SVOM/ECLAIRs (sb26111302) at 2026-11-13T14:31:02 UTC (T0), SVOM performed an automatic slew on the burst location (Saccardi, GCN 46244).
From a preliminary analysis of the 1-bit subimage and source list downloaded via VHF network, one credible candidate is identified, the details of which are presented below.
The position of this candidate is R.A., Dec. 346.32057, 5.17185 degrees, corresponding to:

R.A. (J2000) =  23h05m16.93s    

Dec. (J2000) = +05d10m18.6s 

with an uncertainty of 0.50 arcsec. This location is consistent with the optical afterglow reported by Lin et al. (GCN 46247), Lei et al. (GCN 46248), Li et al. (GCN 46249), and Yin et al. (GCN 46250).
This candidate was detected in both VT_R and VT_B band of the VT observations. The candidate's magnitudes are:
| **date-obs (UTC)**  | **mid-time** | **exposure** | **VT_B mag(AB)** | **VT_R mag(AB)** |
| ------------------- | ------------ | ------------ | ---------------- | ---------------- |
| 2026-11-13T15:34:03 | 63.0  min    | 6*70 sec     | 20.38 +/- 0.02   | 19.31 +/- 0.02   |
| 2026-11-13T16:12:33 | 101.5 min    | 5*70 sec     | 20.94 +/- 0.04   | 19.66 +/- 0.03   |


Magnitudes were not corrected for Galactic reddening.

The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.