{
  "bibcode": "2018GCN.22954....1W",
  "body": "Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), William\nH. Lee (UNAM), Carlos Rom��n-Z����iga (UNAM), Alexander Kutyrev (GSFC), and\nEleonora Troja (GSFC) report:\n\nWe observed the field of the short GRB 180715A (Ukwatta et al., GCN Circ.\n22947) with the COATLI 50-cm telescope and interim imager at the\nObservatorio Astron��mico Nacional on the Sierra de San Pedro M��rtir \n(http://coatli.astroscu.unam.mx) from 2018-07-16 03:40:25 to 08:07:12 UTC\n(9.55 to 14.00 hours after the trigger), obtaining a total of 3.33 hours\nof exposure in the w filter.\n\nWe do not detect any optical sources coincident with the five X-ray\nsources reported by Kennea et al. (GCN Circ. 22953) to a 5-sigma limiting\nmagnitude of\n\nw > 22.4\n\nThis magnitude is calibrated against the USNO-B1 catalog (adjusted to an\napproximate AB system) and is not corrected for Galactic extinction in\nthe direction of the GRB.\n\nWe thank the COATLI technical team (Fernando ��ngeles, Oscar Chapa,\nSalvador Cuevas, Alejandro Farah, Jorge Fuentes, Rosal��a Langarica,\nFernando Quir��s, and Carlos Tejada) and the staff of the Observatorio\nAstron��mico Nacional.",
  "circularId": 22954,
  "createdOn": 1531802692000,
  "email": "alan@astro.unam.mx",
  "subject": "GRB 180715A: COATLI Optical Observations",
  "submitter": "Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>",
  "eventId": "GRB 180715A"
}