TITLE: GCN CIRCULAR NUMBER: 37553 SUBJECT: GRB 240910A: further Swift observations and confirmation of afterglow DATE: 24/09/19 07:02:34 GMT FROM: K.L. Page at U Leicester klp5@leicester.ac.uk

P.A. Evans (U. Leicester), M.H. Siegel (PSU) and K.L. Page (U. Leicester) report on behalf of the Swift-XRT and UVOT teams:

Swift has re-observed the putative afterglow of GRB 240910A, first reported by Julakanti et al. (GCN Circ. 37459) at two additional epochs. 2.8 ks of data were taken between T0+282 ks and T0+329 ks, and a further 4.2 ks between T0+679 ks and T0+708 ks. The X-ray counterpart (D'Ai et al., GCN Circ. 37461) clearly fades between epochs. The light curve can be modelled with a power-law decay with a decay index of alpha=1.1 (+0.4, -0.3).

UVOT observed the field in the u, v and white filters. A faint source was detected in the first epoch at the XRT position with a u magnitude of 20.65 +/- 0.28 with a significance of 3.8 sigma. The second epoch detected no counterpart to a 3 sigma upper limit of 21.51.

We therefore confirm that GOTO24fvl/AT2024vfp is the afterglow of GRB 240910A.

This circular is an official product of the Swift-XRT and UVOT teams.

View this GCN Circular online at https://gcn.nasa.gov/circulars/37553. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...