GCN Circular 43857

C. Wu (NAOC), Z. Kang (CHO), 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 trigger 01709258652 detected by EP/WXT (Yang et al., GCN 43849

) with LATIOS on SVOM/C-GFT. Observations started at 2026-02-26T13:56:46 UTC, ~6.77 min after the trigger.

A sequence of g-, r-, and i-band images was obtained over ~110 min. Photometry of the suggested flare star LP 435-538 (High Proper Motion Star; Yang et al., GCN 43849

) shows a decline from ~13.8 to ~15.4 mag in g-band over ~110 min. The fading was initially fast, then slowed, and was flatter in the r and i bands. This confirms the EP X-ray trigger is associated with a stellar flare.

The photometry was calibrated against nearby Pan-STARRS1 stars and no correction for Galactic dust extinction was applied.

We thank the observation assistants Hong-Xv Xue and Bo-Wen Li at Jilin ob-servatory 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 arcsec x 21 arcsec 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.