GCN Circular 45827
Subject
EP261006a: SVOM/VT optical upper limits
Event
Date
2026-10-07T07:46:48Z (16 hours 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 EP261006a (EP/WXT trigger 01709320985, Lao et al., GCN 45826). The observation started at 2026-10-06T19:05:40 UTC, about 1.27 hr 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 (Lao et al., GCN 45826), compared to the Legacy Survey.
The following measurements are in AB magnitudes and are not corrected for Galactic extinction:
Mid time | Band | Exposure Time | 3-sigma upper limit
1.66 hr VT_B 56*50 s > 23.5 mag
1.66 hr VT_R 56*50 s > 23.5 mag
Our results are consistent with the non-detections from Ondrejov D50 (Novotny et al., GCN 45821) and SVOM/C-GFT (Shi et al., GCN 45823) .
We note that no apparent variability was detected during our observations for the galaxy Gaia DR3 2587044864659595392, which lies within the EP‑FXT error box (Lao et al., GCN 45826).
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.