GCN Circular 45862
EP261007b: SVOM/C-GFT optical upper limits
From: SVOM_group
Issued: 2026-10-08 15:08 UTC
Type: X-ray Transient, Optical Transient

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 EP261007b detected by EP/WXT (Wen et al., GCN 45847) with LATIOS on SVOM/C-GFT. Our observations started at 2026-10-07T15:23:10 UTC, ~ 17.9 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/FXT (Wen et al., GCN 45847) in our images. We measure the following upper limits calibrated against the Pan-STARRS DR1 catalog, and not corrected for Galactic extinction:

g > 21.4 AB (3-sigma, mid-time 1.96 hr after the trigger).
r > 20.9 AB (3-sigma, mid-time 2.05 hr after the trigger).
i > 20.4 AB (3-sigma, mid-time 0.59 hr after the trigger).

Our non-detection is consistent with the non-detections by Ma et al. (GCN 45849), Zhang et al. (GCN 45860), and Mohan et al. (GCN 45861).


We thank the observation assistants B.-W. Li and H.-X. Xue 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.

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