TITLE: GCN CIRCULAR NUMBER: 43258 SUBJECT: GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations DATE: 25/12/30 02:22:30 GMT FROM: Malte Busmann at Ludwig-Maximilians-Universität München <m.busmann@physik.lmu.de> Malte Busmann (LMU), Xander J. Hall (CMU), Brendan O'Connor (CMU), Daniel Gruen (LMU), and Antonella Palmese (CMU) report: We observed the counterpart of Swift GRB 251230A (Lanava et al. GCN 43252, Li et al. GCN 43255) which is spacially and temporally consistent with EP trigger 01709250693 (likely EP251230a) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i, and J-band simultaneously for 2 x 180 s starting at 2025-12-30T01:50:41 UT (28.3 minutes after the trigger). We detect the counterpart in all bands and measure an r-band magnitude of r = 16.30 +/- 0.05 AB mag. The magnitude is calibrated against the PS1 catalog and not corrected for Galactic extinction. We thank Christoph Ries from the Wendelstein Observatory for the rapid response in obtaining these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/43258. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...