{
  "bibcode": "2018GCN.23243....1T",
  "body": "Eleonora Troja (GSFC), Nat Butler (ASU), Alan M. Watson (UNAM),\nAlexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer\n(UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB),\nAntonino Cucchiara (UVI), , Owen Littlejohns (ASU), Enrico\nRamirez-Ruiz (UCSC), Jesus Gonzalez (UNAM), Carlos Roman-Zuniga (UNAM),\nHarvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.),\nand Vicki Toy (UMD) report:\n\nWe re-observed the field of GRB 180914B (Ursi, et al., GCN�� 23226)\nwith the Reionization and Transients Infrared Camera (RATIR;\nwww.ratir.org) on the 1.5m Harold Johnson Telescope at the\nObservatorio Astronomico Nacional on Sierra San Pedro Martir from\n2018/09 17.12 to 2018/09 17.28 UTC (56.53 to 60.22 hours after the\nburst), obtaining a total of 2.49 hours exposure in the r and i\nbands and 1.04 hours exposure in the Z, Y, J, and H bands.\n\nAt the position of the optical/nIR counterpart (Zheng & Filippenko,\nGCN 23237; Troja, et al., GCN 23238), in comparison with the\nSDSS DR9 and 2MASS catalogs, we obtain the following detections:\n\nr = 20.46 +/- 0.01\ni = 20.08 +/- 0.01\nz = 19.74 +/- 0.02\nY = 19.57 +/- 0.02\nJ = 19.33 +/- 0.02\nH = 19.08 +/- 0.03\n\nThese magnitudes are in the AB system and are not corrected for Galactic\nextinction in the direction of the GRB.\n\nCompared to our first night of observations (Troja, et al., GCN 23238),\nthe source significantly faded at an approximate decay rate of t^(-1.4),\nshallower than the value found by De Ugarte Postigo, et al. (GCN 23239)\nat earlier times.\n\nFurther observations are planned.\n\nWe thank the staff of the Observatorio Astronomico Nacional in San Pedro\nMartir.",
  "circularId": 23243,
  "createdOn": 1537168802000,
  "email": "eleonora.troja@nasa.gov",
  "subject": "GRB 180914B: Continued RATIR Optical and NIR Observations",
  "submitter": "Eleonora Troja at GSFC  <eleonora.troja@nasa.gov>",
  "eventId": "GRB 180914B"
}