TITLE:   GCN CIRCULAR
NUMBER:  40716
SUBJECT: EP250612a:  SVOM/VT optical candidate
DATE:    25/06/13 02:45:04 GMT
FROM:    Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>

H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Z. H. Yao, Y. N. Ma, X. H. Han, 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),  Y. L. Hua (PMO, CAS), T. Zhao, Y. J. Song, J. W. Hu , W. Yuan (NAO, CAS) report on behalf of the SVOM and EP Teams: 

SVOM/VT observed the field of EP250612a (Hua et al., GCN 40700) in ToO mode 
in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. 
The observation started at 2025-06-12T21:08:02 UT, about 8.67 hours after the trigger time. 

One uncatalogued source, compared to Legacy Survey, was detected within FXT error circle (Hua et al., GCN 40700), RA = 229.65265, DEC = -26.76771, corresponding to:
 R. A. (J2000) =  15:18:36.6  
 DEC.  (J2000) = -26:46:03.8
Error = 0.5 arcseconds

The brightness of the candidate is derived as below :
 mid-time       band      mag(AB)         exposure
 9.45 hour      VT_B     22.3+/-0.1       20*70 sec
 9.46 hour      VT_R     21.8+/-0.1       19*70 sec

Our photometry was derived 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.