{
  "bibcode": "2018GCN.23018....1C",
  "body": "I. Carrasco (Univ. de Malaga), Y. Hu, E. Fernandez-Garcia, J. C. Tello \nand A. J. Castro-Tirado (IAA-CSIC),\nD. Hiriart and W. H. Lee (UNAM), S. Jeong and I. H. Park (SKKU), M. D. \nCaballero-Garcia (ASU-CAS, CZ) and\nR. Cunniffe (Inst. of Physics, CZ) on behalf of a larger collaboration, \nreport:\n\nThe 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico \nNacional in San Pedro Martir (Mexico)\nautomatically responded in 21s (and 53s after the GRB onset) to the \nSwift trigger of GRB 180721A (Sbarufatti\net al., GCNC 22994). The first image (10s exposure, r-band) was obtained \nat 11:07:10 UT. At the position of\nthe Swift X-ray afterglow (Goad et al. GCNC 22997), no optical afterglow \nis detected down 18.1 mag. Furthermore,\non the co-add of the images obtained until 11:33:52 UT no afterglow is \ndetected down to 21 mag, consistent with\nthe limit reported by Guidorzi et al. (GCNC 22995).\n\nWe thank the staff at Observatorio Astronomico Nacional in San Pedro \nMartir for its excellent support.",
  "circularId": 23018,
  "createdOn": 1532292942000,
  "email": "irene@iaa.es",
  "subject": "GRB 180721A: BOOTES-5/JGT optical observations",
  "submitter": "Irene Carrasco at Inst.De Astrofisica de Andalucia  <irene@iaa.es>",
  "eventId": "GRB 180721A"
}