{
  "bibcode": "2021GCN.29890....1N",
  "body": "A. Nicuesa Guelbenzu, S. Klose, S. Melnikov, B. Stecklum, and U. Laux (all \nTautenburg) report:\n\nWe continued observing the afterglow of GRB 210420B (Moss et al., GCN \n29844) with the Tautenburg 1.34m Schmidt telescope equipped with the \nTAUKAM 6k x 6k CCD camera.\n\nResults are:\n\n- run 2: midtime 01:35 UT, April 22: r' = 21.40 +/- 0.20 mag\n- run 3: midtime 23:24 UT, April 22: r' > 22.7  (3 sigma)\n\nMagnitudes were calibrated against SDSS stars in the field.\n\nOur data (see Stecklum et al., GCN 29863) imply that between the 2nd and \nthe 3rd observing run the decay of the light curve has steepened from \nalpha = 0.99 +/- 0.04 to alpha = 2.3 +/- 0.9, with a break time at 1.14 \n+/- 0.29 days. Probably this is the classical jet break time. No further \nobservations are planned.",
  "circularId": 29890,
  "createdOn": 1619172222000,
  "email": "klose@tls-tautenburg.de",
  "eventId": "GRB 210420B",
  "subject": "GRB 210420B: continued Tautenburg observations",
  "submitter": "Sylvio Klose at TLS Tautenburg  <klose@tls-tautenburg.de>"
}