GCN Circular 29573
Subject
GRB 210218A: Swift-XRT confirmation of afterglow
Date
2021-02-26T16:32:25Z (3 years ago)
From
Boris Sbarufatti at PSU <bxs60@psu.edu>
B. Sbarufatti (PSU), K.L. Page (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team
Swift-XRT has performed follow up observations of GRB 210218A (Sbarufatti et al. GCN Circ. 29529).
The Swift-BAT trigger happened while the burst position in the sky was Moon constrained for XRT and UVOT observations.
A first follow up observation was performed when the target emerged from Moon constraint, with one uncatalogued X-ray source (source #3) detected inside the BAT error circle (Sbarufatti et al. GCN Circ. 29542).
Swift-XRT observed the field again, for a further 4.7 ks, from T+497 ks to T+549 ks. Source #3 has faded below detection, with a 3-sigma upper limit of 2.5E-3 cts s^-1 (equivalent to 4.6E-14 erg cm^-2 s^-1 ), and is thus confirmed to be the burst afterglow.
This circular is an official product of the Swift-XRT team.