{
  "bibcode": "2020GCN.27189....1B",
  "body": "Rosa L. Becerra (UNAM), Margarita Pereyra (UNAM), Alan M. Watson (UNAM),\n Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM),\nMichael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC),\nJosh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC),\nOwen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jes��s Gonz��lez (UNAM),\nCarlos Rom��n-Z����iga (UNAM), Harvey Moseley (GSFC), John Capone (UMD),\nV. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:\n\nWe observed the field of GRB 200224A (Palmer D., et al., GCN 27173) with the\nReionization and Transients Infrared Camera (RATIR; www.ratir.org) on the\n1.5m Harold Johnson Telescope at the Observatorio Astron��mico Nacional on\nSierra San Pedro M��rtir from 2020/02 24.36 to 2020/02 24.54 UTC (5.33\nto 9.66 hours after the BAT trigger), obtaining a total of 3.44 hours\nexposure in the r and i bands.\n\nFor a source within the Swift-XRT error circle, in comparison with the SDSS\nDR9 and 2MASS catalogs, we obtain the following upper limits (3-sigma):\n\n  r > 23.88\n  i > 23.84\n\nThese magnitudes are in the AB system and are not corrected for Galactic\nextinction in the direction of the GRB.\n\nCastro-Tirado et al. (GCN 27176)\nand Stecklum et al. (GCN 27177) report an afterglow candidate at roughly\nmagnitude 22 at about 1 and 2 hours after the burst. Our observations show\nsubsequent fading of this source and confirm that it is the afterglow.\n\nWe thank the staff of the Observatorio Astron��mico Nacional in San Pedro\nM��rtir.",
  "circularId": 27189,
  "createdOn": 1582591786000,
  "email": "rbecerra@astro.unam.mx",
  "subject": "GRB 200224A: RATIR Optical Observations and Confirmation of the Afterglow",
  "submitter": "Rosa Leticia Becerra Godinez at Inst. de Astronoma,UNAM  <rbecerra@astro.unam.mx>",
  "eventId": "GRB 200224A"
}