GCN Circular 46160

Subject
EP261105a: SVOM/VT optical candidate
Event
EP261105a
Date
2026-11-05T15:11:02Z (a day ago)
From
Yinuo Ma <mayn@bao.ac.cn>
Via
Web form
Y. N. Ma, H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Z. H. Yao, J. R. Xu, 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 EP261105a detected by EP/WXT (Guo et al., GCN 46155Loading...
 
 ). SVOM/VT began observing the field at 2026-11-05T10:51:11 UTC, 0.72 hours after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. 

With X-band data available, an uncatalogued candidate (compared to the Legacy Survey), within the 20 arcsec EP/FXT error circle (Guo et al., GCN 46155Loading...
 
 ), is detected in our stacked VT_R image at coordinates R.A., Dec. 91.00143, -54.26428 degrees, corresponding to:

R.A. (J2000)= 06:04:00.34
Dec. (J2000)= -54:15:51.38

with an uncertainty of ~0.5 arcsec.

The preliminary photometric measurements in AB magnitudes are as follows:

mid time (h) | exposure time (s) | band |  mag (AB) 
-------------|-------------------|------|-----------------
     0.87    |      20*50        | VT_B |  >23.1 (3-sigma)
     0.85    |      18*50        | VT_R |  22.3+/-0.2 

Our photometry was not corrected for Galactic extinction. More detailed investigation will be performed once more data are available.

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.