GCN Circular 40433
Subject
EP250511a: SVOM/VT optical candidate comfirmation
Date
2025-05-12T01:50:53Z (12 hours ago)
Edited On
2025-05-12T13:37:27Z (43 minutes ago)
From
Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Via
Web form
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. Considering the possible host galaxy's brightness (Bchneider et al., GCN 40431) and blue color，the photometry might be contaminated by the host galaxy's light, particularly in the VT_B band.
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.