TITLE: GCN CIRCULAR NUMBER: 45434 SUBJECT: GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation DATE: 26/08/24 06:29:10 GMT FROM: SVOM_group <svomgroup@bao.ac.cn> C. Plasse (HKU), Z.M. Wang (BNU) and H. Goto (RIKEN, CEA) report on behalf of the SVOM and Einstein Probe teams: We performed two additional observations at the location of the SVOM/ECLAIRs GRB 260818A (Yin et al., GCN 45391) with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observations started on 2026-08-18 at 18:10:40 UT (0.76 days after the trigger) and on 2026-08-20 at 18:05:05 UTC (2.75 days after the trigger), both with a total exposure time of ~6000 s. The source EPF_J232025.8-320549, detected by EP/FXT about 1.67 hr after the SVOM trigger, reported in GCN 45400, fades by a factor 2 in the second observation, from a flux of (13.1 +/- 2.6) x 10^-14 erg/s/cm^-2 down to a flux of (6.7 +/- 1.9) x 10^-14 erg/s/cm^-2 (0.3-10 keV; 1-sigma uncertainty). At this source position of RA, Dec: 350.1064 -32.0978 (with an error radius of 10 arcsec ), 5.9 arcmin from ECLAIRs position, no X-ray source is detected in the third observation. The fading behaviour of this X-ray source confirms it as the afterglow of GRB 260818A. We encourage further multi-wavelength follow-up of this source. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/45434. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...