TITLE: GCN CIRCULAR NUMBER: 41673 SUBJECT: EP 250827B: Detection of the fading supernova counterpart by LCO. DATE: 25/09/03 15:34:43 GMT FROM: ankur ghosh at CAPP, University of Johannesburg <ghosh.ankur1994@gmail.com> Ankur Ghosh, Soebur Razzaque (CAPP, University of Johannesburg), Rahul Gupta (NASA GSFC), Alexander Moskvitin, Yulia Sotnikova (SAO RAS), Naveen Dukiya (ARIES)on behalf of a larger collaboration. We observed the field of the EP250827B/AT 2025wkm (Schroeder et al., GCN 41635) in V, r filter of the 0.4-m SCICAM QHY600 at the Las Cumbres Observatory Global Telescope (LCOGT) node located at Haleakala Observatory, Hawai . The 0.4 m SCICAM QHY600 is equipped with 9576 x 6388 pixel CCD (FOV: 1.9 x 1.2 degrees, scale: 0.74 arcsec/pixel) but we only used the FOV of 30 x 30 arcmin for our observation. Observations began on September 03, 2025, starting 7.32 days after the GRB trigger. Further observations are currently ongoing. We clearly detect the optical transient (OT) reported by GCNs (Schroder et al., GCN 41635; Hall et al., GCN 41636; Hall et al., GCN 41641; Eyles-Ferris et al., GCN 41655; Ma et al., GCN 41667; Eyles-Ferris et al., GCN 41669, He et al,. GCN 41671) in our r band image. Eyles-Ferris et al., GCN 41655 reported the detection of the rise of the associated Ic-BL supernova, with a measured magnitude of 18.91 at 5.61 days after the explosion. The source subsequently faded by ~1 mag within 1.71 days. |Date| |UTstart| |t-T0 (days)| |Exp (sec)| |Filter| |Magnitude| -------------------------------------------------------------------------------------------------- 2025-09-03 13:58:49.728 7.32 3 x 900 r r = 19.81 +/- 0.05 The field was calibrated against nearby APASS stars, with magnitudes converted using Lupton (2005) equations, and has not been corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/41673. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...