TITLE: GCN CIRCULAR NUMBER: 38943 SUBJECT: GRB 250114A: LCOGT optical afterglow i-band detection DATE: 25/01/14 17:01:56 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias ipf@iac.es

I. Pérez-Fournon and F. Poidevin (IAC and ULL)

We observed the field of GRB 250114A, detected by Swift BAT, XRT, and UVOT (Klingler et al., GCN 38927; Beardmore et al., GCN 38936) using one of the Las Cumbres Observatory global telescope network (LCOGT) 1-m telescopes, equipped with Sinistro cameras, at the LCOGT node at Siding Spring Observatory (Australia). The observation, a single 600-sec exposure in the SDSS i' filter, started at 2025-01-14 13:59:32 UT, i.e. ~ 6.44 hr after the Swift BAT trigger. The optical afterglow is detected at a position consistent with the UVOT coordinates (Klingler et al., GCN 38927). Me measure a magnitude of i' = 20.17 +/- 0.22, calibrated against PanSTARRS DR2 stars and not corrected for Galactic extinction.

Other groups have reported optical and near-IR detections of the afterglow: An et al. (GCN 38929), Malesani and Izzo (GCN 38930), Brivio et al. (GCN 38933) and Malesani et al. (GCN 38934). A redshift of z = 4.732 has been reported by Malesani et al. (GCN 38934).

This work makes use of observations from the Las Cumbres Observatory global telescope network (LCOGT observing programme IAC2024B-004, SGLF).

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