TITLE: GCN CIRCULAR NUMBER: 41576 SUBJECT: EP250827a: LCO observations show fading optical counterpart DATE: 25/08/28 14:18:51 GMT FROM: Rob Eyles-Ferris at U of Leicester <raje1@leicester.ac.uk> R. A. J. Eyles-Ferris (Leicester), J. A. Quirola-Vasquez (Radboud), A. J. Levan (Radboud and Warwick), P. G. Jonker (Radboud), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), F. E. Bauer (SSI and UTA), and J. Chacón (PUC) report on behalf of a larger collaboration: We observed the location of the optical counterpart (Levan et al., GCN 41554; Li et al., GCN 41555; Levan et al., GCN 41557; Lipunov et al., GCN 41558; Gritsevich et al., GCN 41559; An et al., GCN 41560; Ghosh et al., GCN 41564; O’Neill et al., GCN 41567; Pérez-Fournon et al., GCN 41568; Passaleva et al., GCN 41570) to EP250827a (Hua et al., GCN 41553; Ni et al., GCN 41573) with the Sinistro instruments mounted on 1-m telescopes at the LCO SAAO and Cerro Tololo Inter-American Observatory nodes. 5x300 s exposures were obtained in each of the SDSS u, g and r filters with start times from 2025 Aug 27 at 22:38:04 to 2025 Aug 28 04:36:48 UT. The counterpart is clearly detected in both the g and r filters and is marginally detected in the u filter image. At 15.0 hr after the EP trigger, we measure r = 19.99 +/- 0.05, ~1.5 mags fainter than observed by Ghosh et al. (GCN 41564). Assuming an unbroken power-law decay between the two epochs, we derive a temporal index alpha ~ 1.4 for the decay. View this GCN Circular online at https://gcn.nasa.gov/circulars/41576. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...