TITLE: GCN CIRCULAR NUMBER: 43123 SUBJECT: GRB 251214B: LCO detection of the optical counterpart DATE: 25/12/15 14:21:49 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf@iac.es> I. Pérez-Fournon (IAC and ULL), F. Poidevin (IAC and ULL), D. Cano-Morales, A.E. Hernández-Díaz, I. Correa-Plasencia, E. Lekaroz-Urriza, M. Quintana-Ansaldo (all ULL), and A. López-Oramas (IAC and ULL) Following the detection of the long GRB 251214B, detected by Fermi GBM (Fermi GBM team, GCN #43088), Swift BAT, XRT, and UVOT (Eyles-Ferris et al., GCN #43089; Evans et al., GCN #43098; Kuin and Eyles-Ferris, GCN #43105; and Burrows et al., GCN #43112), and GECAM-B (Luo et al., GCN #43113), we observed the field with one of the two Las Cumbres Observatory (LCO) 1-m telescopes equipped with Sinistro cameras located at the LCO node at Siding Spring Observatory near Coonabarabran, New South Wales, Australia. The observation, a single exposure of 60 sec in the SDSS r' filter, started on 2025-12-14 at 10:26:57 UT, about 1.41 hours after the Fermi, Swift, and GECAM-B triggers. The optical counterpart first detected by Swift UVOT (Eyles-Ferris et al., GCN #43089) is clearly detected in our image with a preliminary magnitude of r' = 19.18 +/- 0.10, calibrated against PanSTARRS-1 DR2 stars and not corrected for Galactic extinction. Our result is consistent with other optical and UV detections (Eyles-Ferris et al., GCN 43089; Kang et al., GCN #43093; Gress et al., GCN #43095; Fu et al., GCN #43097; Gupta et al., GCN #43100; Watson et al., GCN #43103; and Kuin and Eyles-Ferris, GCN #43105). Our preliminary photometry is not corrected for the light of the likely host galaxy discussed by Gress et al. (GCN #43095), and Watson et al. (GCN #43103) at a photometric redshift of z = 0.709 +/- 0.078 (Duncan, 2022). This work makes use of observations from the Las Cumbres Observatory global telescope network (LCO program IAC2025B-008, SGLF and Superluminous Supernovae surveys). This work made use of the Astro-COLIBRI platform (P. Reichherzer et al. 2021, ApJS, 256, 5). View this GCN Circular online at https://gcn.nasa.gov/circulars/43123. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...