TITLE: GCN CIRCULAR NUMBER: 45236 SUBJECT: GRB 260727A: EP/FXT follow-up observations DATE: 26/07/28 02:53:14 GMT FROM: SVOM_group <svomgroup@bao.ac.cn> Ruizhi Li (YNAO), Ziming Wang (BNU), An Li (BNU), Yifang Liang (PMO), Wenjin Xie (NAOC), Donghua Zhao (NAOC), Clara Plasse (HKU) and Andrea Saccardi (CEA) report on behalf of the SVOM mission team: EP-FXT performed a follow-up observation of GRB 260727A detected by SVOM/ECLAIRs (Li et al., GCN 45220), which also triggered AstroSat CZTI (Harsha K. H. et al., GCN 45225) and Glowbug (Cheung et al., GCN 45233). The follow-up observation started at 2026-07-27T05:27:41 (UTC), about 5.09 hours after the SVOM-ECLAIRs trigger, with a total exposure time of around 6.1 ks. An uncatalogued X-ray source was found within the ECLAIRs error circle. The position of the source is at R.A., Decl. = 331.7702, 74.5296 deg (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic). The 0.5-10 keV spectrum can be fitted by an absorbed powerlaw model with a Galactic hydrogen column density of (0.55 +/-0.10) x 10^22 cm^-2 and a photon index of 2.61 +/- 0.07. The average unabsorbed flux is 2.65 (+0.55, -0.35) x 10^(-12) erg/s/cm^2 in the 0.5-10 keV energy band (90% C.L.). Optical follow-up observations of the burst were carried out by LCO (Shi et al., GCN 45223), Kilonova-Catcher (Freeberg et al., GCN 45224), GOTO (Starling et al., GCN 45226), RAPAS (Lechapelain et al., GCN 45228), and WINTER (Mohan et al., GCN 45231). The Burst Advocate (BA) on shift for this alert is Ziming Wang: 202421101144@mail.bnu.edu.cn. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/45236. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...