GCN Circular 45849
EP261007b: SVOM/VT optical upper limits
From: Yinuo Ma
Issued: 2026-10-08 06:45 UTC
Type: X-ray Transient, Optical Transient

Y. N. Ma, H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Z. H. Yao, J. R. Xu, L. J. Chen, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team.

SVOM/VT performed a Target of Opportunity observation of EP261007b detected by EP/WXT (Wen et al., GCN 45847). SVOM/VT began observing the field at 2026-10-07T16:05:33 UTC, 1.005 hours after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.

No uncatalogued candidate was identified in our stacked images within the error box provided by EP/FXT position (Wen et al., GCN 45847), 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
1.23 hr | VT_B | 26*50 s | > 23.3 mag
1.23 hr | VT_R | 26*50 s | > 23.0 mag

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.

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