TITLE: GCN CIRCULAR NUMBER: 40433 SUBJECT: EP250511a: SVOM/VT optical candidate comfirmation DATE: 25/05/12 01:50:53 GMT FROM: Huali Li at at NAOC, SVOM lhl@nao.cas.cn
H. L. Li, L. P. Xin, Y. L. Qiu, J. Wang, C. Wu, Z. H. Yao, Y. N. Ma, X. H. Han, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei, T. Y. Lian (NAOC), A. Li (BNU), Y. L. Wang (NAOC; ICE, CSIC-IEEC), C. C. Jin (NAOC) report on behalf of the SVOM and Einstein Probe (EP) teams:
SVOM/VT observed the X-ray transient EP250511a (Lian et al., GCN 40429) in ToO mode in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. The observations started at 2025-05-11T15:46:49 UT, about 7.78 hours after the trigger.
The candidate reported by Bchneider et al. (GCN 40431) within the error box of EP/FXT (Lian et al., GCN 40429) was clearly detected by VT in both channels. The brightness of the candidate was derived as below :
Mid-time Band mag(AB) exposure 8.16 hour VT_B 22.41 +/- 0.13 36*70 sec 8.14 hour VT_R 22.29 +/- 0.13 36*70 sec 9.77 hour VT_B 22.65 +/- 0.15 37*70 sec 9.78 hour VT_R 22.52 +/- 0.16 37*70 sec
Our photometry was estimated in AB magnitude and not corrected for Galactic extinction.
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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