TITLE: GCN CIRCULAR NUMBER: 38829 SUBJECT: GRB 250106A: SVOM/VT optical candidate DATE: 25/01/06 11:51:02 GMT FROM: SVOM_group svomgroup@bao.ac.cn

SVOM/VT commissioning team: Y. L. Qiu, H. L. Li, C. Wu, D. H. Zhao, L. P. Xin, X. H. Han, J. Wang, W. J. Xie, H. B. Cai, Y. Xu, Y. J. Xiao, P. P. Zhang, J. S. Deng, L. Lan, X. M. Lu, R. S. Zhang, Z. H. Yao (NAOC), J. Zhang, L. J. Dan, G. Y. Zou, C. J. Wang, Y. F. Du, C. Huang (XIOPM)

SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), Arnaud Claret (CEA), Zi-Gao Dai (USTC), Frédéric Daigne (IAP), Jin-Song Deng (NAOC), Olivier Godet (IRAP), Andrea Goldwurm (APC), Diego Götz (CEA), Xu-Hui Han (NAOC), Cyril Lachaud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs.Paris), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Shao-Lin Xiong (IHEP), Bing Zhang (UNLV)

report on behalf of the SVOM team:

The SVOM/VT conducted observations of GRB 250106A (Zhao et al., GCN 38826) after the automatic slew of the platform. The observations were carried out in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously.

In the stacked VT_R image with an exposure time of 14*100 sec, an uncatalogued source was detected in the errorbox of XRT source #2(P. A. Evans et al., GCN 38828), while no any new source was detected within the errorbox of XRT source #1, compared to Pan-STARRS catalog.

The brightness of the uncatalogued source was VT_R=22.5+/-0.3 mag in AB miniguide at the mid time of 0.965 hours after the burst. The source was not detected in VT_B stacked image with a 3 sigma limit of 23.3 mag at the mid time of 0.966 hours after the burst.

The source is located at RA, Dec = 117.37078 63.70817 deg, which is equivalent to: RA (J2000) : 07:49:28.99 Dec (J2000): +63:42:29.4 with an uncertainty of 0.5 arcsec.

More deep follow-ups are encouraged for the nature of the source.

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

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