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GCN Circular 37819

Subject
GRB 241018A: SVOM/VT follow-up and optical candidate
Date
2024-10-18T19:43:45Z (a month ago)
From
Liping Xin at NAOC, SVOM <xlp@nao.cas.cn>
Via
Web form
SVOM/VT commissioning team: Y. L. Qiu, C. Wu, L. P. Xin, H. L. Li, 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, (NAOC), J. Zhang, L. J.  Dan, G. Y. Zou, C. J. Wang, Y. F. Du, C. Huang (XIOPM), H. Zhou (PMO)

SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), Olivier Godet (IRAP), Arnaud Claret (CEA), Zi-Gao Dai (USTC), Frédéric Daigne (IAP), Jin-Song Deng (NAOC), 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), Bing Zhang (UNLV)

report on behalf of the SVOM team:

VT started to observe the field of GRB 241018A triggered by SVOM/Eclairs(Atteia et al., GCN 37812Not found
 
 
) in an automatic way after the slew of the satellite. The VT conducted observations simultaneously in two channels: VT_B (400nm-650nm) and VT_R (650nm-1000nm).

With the VHF data started at 2024-10-18T12:00:28 UT, in which the cataloged source brighter than 21 mag is completed relative to the PS1 catalog. An uncatalogued source was found within the errorbox of Eclairs and has an angular distance of 1.8509 arcmin from the position of MXT (Maggi et al., 37814). 

The position is RA=04:31:59, DEC=+43:01:12, error=1.0 arcsec, J2000.

The brightness of the source is fading rapidly in 10 min, from 20.9 mag to 22.2 mag for VT_B and from 18.7 mag to 20.5 mag for VT_R.

We proposed that this source might be the counterpart of the burst. More analysis is continuing with X-band data. 

Further follow-ups are encouraged especially in red wavelength. 

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.