{
  "submitter": "Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>",
  "version": 2,
  "editedBy": "Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>",
  "format": "text/plain",
  "eventId": "GRB 141121A",
  "circularId": 17105,
  "body": "Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H.\nLee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J.\nXavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC),\nEleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), José\nA. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos\nRomán-Zúñiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report:\n\nWe observed the field of GRB 141121A (Lien et al., GCN 17075) with the\nReionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m\nHarold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San\nPedro Mártir from 2014/11 27.31 to 2014/11 27.54 UTC (147.50 to 153.22 hours\nafter the BAT trigger), obtaining a total of 4.62 hours exposure in the r, i and\nz bands.\n\nFor a source within the Swift-XRT error circle, in comparison with the SDSS DR9,\nwe obtain the following detections:\n\nr = 21.59 +/- 0.04\ni = 21.39 +/- 0.04\nz = 20.89 +/- 0.26\n\nThese magnitudes are in the AB system and are not corrected for Galactic\nextinction in the direction of the GRB.\n\nThe afterglow has faded by about 0.33 magnitudes in r and i compared to our\nobservations at 126 hours (Butler et al., GCN 17101). This corresponds to a\nfurther steepening of the temporal power law from t^-1.3 between 102 and 126\nhours (Watson et al., GCN 17100) to t^-1.8 between 126 and 150 hours.\n\nWe detect a source 2.3 arcsec to the east of the optical transient, with r =\n23.22 +/- 0.13, i = 23.11 +/- 0.13, and z > 21.02. This source is visible in\nearlier images, but due to its proximity to the brighter optical transient our\nautomatic pipeline failed to produce photometry for it from those earlier\nimages. We expect better photometry for this source once the afterglow has faded\nfurther.\n\nFor a flat universe with H0 = 70 km/s/Mpc and OmegaM = 0.29, and at a redshift\nof 1.47 (Perley et al., GCN 17081) the angular separation of the afterglow and\nthis source corresponds to a projected separation of 20 kpc. This separation is\nconsistent with the source being the host galaxy of the GRB.\n\nIf this source is the host galaxy, our photometry suggests that it is among the\nbrightest ever observed at this redshift for optically bright GRBs (Hjorth et\nal. 2012, ApJ, 756, 187; Perley et al. 2013, ApJ, 778, 128).\n\nWe thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.",
  "editedOn": 1731006895864,
  "bibcode": "2014GCN.17105....1W",
  "createdOn": 1417105015000,
  "email": "alan@astro.unam.mx",
  "subject": "GRB 141121A: Continued RATIR Optical Observations"
}