GCN Circular 45657
Subject
EP260920a: SVOM/VT optical upper limits
Event
Date
2026-09-20T10:35:29Z (2 days ago)
From
Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Via
Web form
H. L. Li, Y. N. Ma, C. Wu, L. P. Xin, Y. L. Qiu, Z. H. Yao, J. R. Xu, L. J. Chen, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. T. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team.
SVOM/VT performed ToO observation on the field of EP260920a (Ni et al., GCN 45649, GCN 45655). The observation started at 2026-09-20T00:48:38 UTC, about 43 minutes after trigger in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
No credible uncatalogued candidates were identified in our stacked images within the error box of EP-FXT (Ni et al., GCN 45655) compared to the Legacy Survey.
The following measurements are in the AB magnitude and are not corrected for Galactic extinction:
Mid time | Band | Exposure Time | 3-sigma upper limit
1.65 hr VT_B 72*50 sec > 24.0 mag
1.81 hr VT_R 93*50 sec > 24.0 mag
Our results are consistent with the non-detections from LCO (Liu et al., GCN 45653) and COLIBRÍ (Dornic et al., GCN 45654) .
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.