GCN Circular 41244
Subject
GRB 250806A: SVOM/VT optical upper limit
Event
Date
2025-08-06T09:24:01Z (7 months ago)
Edited On
2025-08-06T14:11:13Z (7 months ago)
From
Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Via
Web form
C. Wu, L.P. Xin, Y. L. Qiu, H.L. Li, Z.H. Yao, Y.N. Ma, X.H. Han, J. Wang, W.J. Xie, Y. Xu, H.B. Cai, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM team.
SVOM/VT performed an automatic slew on the burst triggered by SVOM/ECLAIRs (Xie et al., GCN 41243). SVOM/VT began observing the field automatically at 2025-08-06T08:02:01.000 UTC, 227 seconds after the T0, with the slew of the platform triggered on-board, in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
With downlinked VHF data, no any candidates were found in stacked images within the errorbox of SVOM/MXT (Xie et al., GCN 41243) compared to Legacy survey.
The 3 sigma limit in AB magnitude was derived as follows:
---------------------------------------------------------
(T-T0)_mid(s) exptime(s) Band upperlim (3sigma)
377 300 VT_R 21.5
More deeper photometry in near-inferred is encouraged to investigate the nature of the burst.
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.