TITLE: GCN CIRCULAR NUMBER: 38952 SUBJECT: GRB 250114B: Liverpool Telescope optical upper limit DATE: 25/01/15 12:43:55 GMT FROM: Ben Gompertz at U of Birmingham b.gompertz@bham.ac.uk
B. P. Gompertz (U. Birmingham), Dimple (U. Birmingham), D. B. Malesani (DAWN/NBI and Radboud) and A. J. Levan (Radboud) report:
We initiated follow-up observations of the INTEGRAL-detected GRB 250114B (Gotz et al., GCN 38938) with the IO:O camera on the 2m robotic Liverpool Telescope (LT). Observations began at 19:17:04 UT on 2025-01-14 and consisted of 5x120 s exposures in the SDSS r filter.
We do not detect the candidate afterglow reported by MITSuME Akeno (Sasada et al., GCN 38950) nor any new source within the localisation region of XRT source 2 (Williams et al., GCN 38949) to a 3-sigma limiting magnitude of r(AB) > 21.17, at a mid-time of 6.24 hr after trigger. Observations were calibrated against nearby SDSS stars and are not corrected for foreground extinction.
Our non-detection, and those reported by GIT (Goyal et al., GCN 38942) and OHP/T193 (Schneider et al., GCN 38947), support the rapid fading detected by MITSuME Akeno over a longer time baseline, indicating the source is likely the optical afterglow of GRB 250114B.
In Legacy Survey images of the field there is no object directly underlying the afterglow position. The closest object is a galaxy with r = 24.4 and an offset of ~1.5 arcseconds. This galaxy has a probability of chance alignment of ~5% (cf. Bloom et al. 2002, ApJ, v123, p1111).
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