GCN Circular 41226
Subject
EP250730a: SVOM/VT optical upper limit
Event
Date
2025-08-04T09:37:30Z (4 months ago)
From
zhyao@bao.ac.cn
Via
Web form
Z. H. Yao, H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), B. T. Wang (YNAO) report on behalf of the SVOM/VT team.
SVOM performed a Target of Opportunity observation of EP250730a detected by EP/WXT (Wang et al., GCN 41207). SVOM/VT began observing the field at 2025-07-31T10:36:57.506 UTC, 28.5 hours after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
No uncataloged candidates were detected in our single or stacked images within the error box provided by EP/WXT (Wang et al., GCN 41207), the three sigma limits are:
mid-time (UTC) | exposure time (s) | band | upper limit (AB)
--------------------|-------------------------|------|-----------------
2025-07-31T11:47:09 | 19*100 | VT_B | 23.5
2025-07-31T11:47:09 | 19*100 | VT_R | 23.0
Our results are consistent with COLIBRÍ (Magnani et al., GCN 41209) and Global MASTER-Net (Lipunov et al., GCN 41210).
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Centre 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.