TITLE: GCN CIRCULAR NUMBER: 39436 SUBJECT: EP250223a: NOT optical afterglow candidate DATE: 25/02/23 21:46:49 GMT FROM: Andrew Levan at Radboud University <a.levan@astro.ru.nl> Benjamin N. Hauptmann (NOT and DTU Space), Yfke Bethlehem (Kapteyn Astronomical Institute, Groningen, and ING), Andrew J. Levan (Radboud and Warwick), Daniele B. Malesani (DAWN/NBI and Radboud), Antonio Martin-Carrillo (UCD), Franz E. Bauer (PUC), Peter G. Jonker (Radboud) and Dong Xu (NAOC), report on behalf of a larger collaboration: We observed the location of EP250223a (Lian et al. GCN 39429) with the Nordic Optical Telescope (NOT). Observations in the r-band began at 20:36 UT, approximately 5.53 hr after the trigger time. In the first 300 s exposure we clearly detect a new point source, not visible in archival DSS and Pan-STARRS imaging of this field, at a location of RA(J2000) = 06:33:05.723 DEC(J2000) = -22:26:40.32 These coordinates are within the FXT X-ray uncertainty region, making this source the likely afterglow of EP250223a. The source has an AB magnitude r = 19.7, calibrated against nearby Pan-STARRS objects. Further observations are in progress. View this GCN Circular online at https://gcn.nasa.gov/circulars/39436. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...