{
  "bibcode": "2020GCN.27600....1S",
  "body": "B. Sbarufatti (PSU), N. P. M. Kuin (UCL-MSSL), P. A. Evans (U. Leicester), and J. D. Gropp (PSU) report on behalf of the Swift team:\n\nSwift XRT performed follow up observations on the afterglow candidate reported by Page et al. (GCN #27561).\n\nXRT data now comprise 6.1 ks of Photon Counting data covering times from T+20 ks to T+370 ks.\n\nThe light curve is best fit by a power-law with decay index 1.6 +/- 0.3. We thus confirm that this is indeed the afterglow of GRB 200412B.\nThe latest results can be viewed via: https://www.swift.ac.uk/xrt_curves/00020981/\n\nIn the initial Swift observation about 20ks after the trigger, the source was not in the UVOT field of view, which is smaller than that of the XRT.  In the follow up observations around 360ks after the trigger we obtained the following 3-sigma upper limits to the source (Vega magnitudes, uncorrected for reddening):\nfilter exposure   UL (mag)\n v       374       >19.76\n b       374       >20.74\n u       374       >20.41\nuvw1     749       >20.31\nuvm2    1201      >20.48\nuvw2    1499      >20.83 \n\nThis circular is an official product of the Swift team.",
  "circularId": 27600,
  "createdOn": 1587142927000,
  "email": "bxs60@psu.edu",
  "subject": "GRB 200412B: Swift XRT confirmation of afterglow and UVOT upper limits",
  "submitter": "Boris Sbarufatti at PSU  <bxs60@psu.edu>",
  "eventId": "GRB 200412B"
}