{
  "bibcode": "2020GCN.29149....1D",
  "body": "P. D'Avanzo, S. Covino, D. Fugazza, A. Melandri (INAF-OAB), D. B. Malesani (DTU space) \non behalf of the REM team, report:\n\nWe observed the field of GRB 201221A (Page et al., GCN Circ. 29096) with the REM 60cm robotic \ntelescope located at the ESO premise of La Silla (Chile). The observations were performed starting \non 2020 December 21 at 07:10:33 UT (i.e. 92 seconds after the burst) and were carried in the g, r, i, z \nbands simultaneously. \n\nFrom preliminary photometry, we estimate the following magnitudes and 3sigma upper limits for the \nafterglow reported by Malesani et al. (GCN Circ. 29100):\n\ng > 17.9\nr > 17.8\ni > 17.7\nz = 15.8 +/- 0.3\n\n(AB; calibrated against the APASS catalogues), at a mean time of 97 seconds after the GRB t0. \nBy combining our z-band magnitude with the one reported by Malesani et al., we infer an afterglow \ntemporal decay (f propto t^(alpha)) of alpha ~ -1.2 between 97 seconds and 2100 seconds after the GRB t0.",
  "circularId": 29149,
  "createdOn": 1608734761000,
  "email": "pda.davanzo@gmail.com",
  "subject": "GRB 201221A: REM early-time afterglow detection",
  "submitter": "Paolo D'Avanzo at INAF-OAB  <pda.davanzo@gmail.com>",
  "eventId": "GRB 201221A"
}