TITLE:   GCN CIRCULAR
NUMBER:  45823
SUBJECT: EP trigger 01709320985: SVOM/C-GFT optical upper limits
DATE:    26/10/07 05:05:27 GMT
FROM:    SVOM_group <svomgroup@bao.ac.cn>

Y.Y. Shi (GXU), Z. Kang (CHO), C. Wu , L.P. Xin, X.H. Han, P.P. Zhang, X.M. Lu (NAOC), Z.W. Li, Y. Lv (CHO), R.S. Zhang, Y.J. Xiao, Y.L. Qiu, J. Wang, J.S. Deng, L. Huang, J.Y. Wei (NAOC) report on behalf of the SVOM/C-GFT team:

 
We observed the field of Einstein Probe/WXT trigger 01709320985 with LATIOS on SVOM/C-GFT. Our observations started at 2026-10-06T17:57:33 UTC, ~ 7.5 min after the trigger. 
 
We obtained follow-up imaging in g, r, and i bands. After preliminary analysis, no credible candidate was detected within the error box provided by EP/WXT (RA, Dec =
21.806, +12.900, r = 3.1') in our images. We measure the following upper limits calibrated against the Pan-STARRS DR1 catalog, and not corrected for Galactic extinction:
 
g > 20.7 AB (3-sigma, mid-time 12.7 min after the trigger).
r > 20.3 AB (3-sigma, mid-time 16.3 min after the trigger).
i > 20.0 AB (3-sigma, mid-time 9.2 min after the trigger).
 
Our non-detection is consistent with the non-detections by Novotny et al. (GCN 45821). 
 
 
We thank the observation assistants  Y.-H. Hao and C.-L. Guo at Jilin observatory for their excellent support.
 
The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcmin x 21 arcmin FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching.