{
  "bibcode": "2021GCN.29573....1S",
  "body": "B. Sbarufatti (PSU), K.L. Page (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team\n\nSwift-XRT has performed follow up observations of GRB 210218A (Sbarufatti et al. GCN Circ. 29529).\nThe Swift-BAT trigger happened while the burst position in the sky was Moon constrained for XRT and UVOT observations. \nA 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).\n\nSwift-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.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 29573,
  "createdOn": 1614357145000,
  "email": "bxs60@psu.edu",
  "subject": "GRB 210218A: Swift-XRT confirmation of afterglow",
  "submitter": "Boris Sbarufatti at PSU  <bxs60@psu.edu>",
  "eventId": "GRB 210218A"
}