{
  "editedBy": "Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>",
  "bibcode": "2015GCN.18096....1W",
  "eventId": "GRB 150728A",
  "editedOn": 1731005832527,
  "circularId": 18096,
  "createdOn": 1438200423000,
  "body": "Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William \nH. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), \nJ. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara \n(ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico \nRamirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), \nJesús González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), \nand Harvey Moseley (GSFC) report:\n\nWe observed the field of GRB 150728A (Krimm et al., GCN 18087) with the \nReionization and Transients Infrared Camera (RATIR; www.ratir.org) on the \n1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on \nSierra San Pedro Mártir from 2015/07 29.19 to 2015/07 29.48 UTC (15.73 to \n22.75 hours after the BAT trigger), obtaining a total of 5.29 hours \nexposure in the r, i, and z bands.\n\nThe brightest source within the enhanced Swift/XRT error circle (Beardmore \net al., GCN 18088) is the cataloged source 2MASS 19285425+3354576, for \nwhich we determine a position of 19:28:54.26 +33:54:57.6 (J2000, �0.5\") \nand magnitudes:\n\n   r 16.71 ± 0.02\n   i 16.49 ± 0.01\n   z 16.14 ± 0.04\n\nWe detect two other uncataloged sources on the edge of the error circle. \nFor source A we determine a position of 19:28:54.80 +33:54:58.2 (J2000, \n�0.5\") and magnitudes:\n\n   r     21.37 ± 0.04\n   i     20.89 ± 0.04\n   z     19.54 ± 0.13\n\nand for source B we determine 19:28:54.25 +33:55:2.6 (J2000, �0.5\") and:\n\n   r     21.11 ± 0.04\n   i     20.73 ± 0.03\n   z     20.21 ± 0.21\n\nThese magnitudes are in comparison with the USNO-B1 and 2MASS catalogs, \nare in the AB system, and are not corrected for Galactic extinction in the \ndirection of the GRB.\n\nOur source A appears to correspond to the source reported by Dichiara et \nal. (GCN 18090). If this association is correct, then there is little \nevidence for fading between about 1 hour and 16-23 hours.\n\nWe thank the staff of the Observatorio Astronómico Nacional in San Pedro \nMártir.",
  "format": "text/plain",
  "email": "alan@astro.unam.mx",
  "subject": "GRB 150728A: RATIR Optical Observations",
  "version": 2,
  "submitter": "Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>"
}