{
  "subject": "GRB 170906C: COATLI Observations",
  "eventId": "GRB 170906C",
  "bibcode": "2017GCN.21837....1W",
  "createdOn": 1504727241000,
  "circularId": 21837,
  "submitter": "Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>",
  "email": "alan@astro.unam.mx",
  "body": "Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Carlos\nRom��n-Z����iga (UNAM), and William H. Lee (UNAM) report:\n\nWe observed the field of the GRB 170906C (Siegel et al., GCN Circ.\n21826) with the COATLI 50-cm telescope and interim CCD imager (Watson et\nal. 2016, Proc. SPIE, 9908, 50) at the Observatorio Astron��mico Nacional\non the Sierra de San Pedro M��rtir from 2017-09-06 08:17 to 12:11\nobtaining a total of 2.93 hours of observation in the clear w filter.\n\nWe do not detect a source within the enhanced XRT error region reported\nby Evans et al. (GCN Circ. 21831). Calibrating with respect to the\nUSNO-B1 catalog, we estimate a 3-sigma upper limit of:\n\nw > 21.7\n\nThis magnitude is in the AB system and is not corrected for Galactic\nextinction in the 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."
}