{
  "bibcode": "2017GCN.21417....1C",
  "body": "A. Cucchiara, D. Morris (U. of the Virgin Islands), and\r\nN. Orange (OrangeWave), report on behalf of a larger\r\ncollaboration:\r\n\r\n\"On August 4.79 UT  (T_0 +7.0h) we began observing the\r\ncenter of the field of GRB 170804A (Cholden-Brown et al.\r\nGCN 21410, Emery et al. GCN 21411) using the Las Cumbres\r\nObservatory 1m telescope located in Siding Spring\r\nObservatory.\r\n\r\nUnder poor sky conditions (seeing ~2.6 arcseconds) we\r\nperformed a series of 5x240s observations in SDSS r' and i���\r\nbands for a total of 20 minutes on sky in each filter at\r\naverage airmass of 1.3.\r\n\r\nIn the full median stacked images we identified no optical\r\ncounterpart within the center of the Swift-XRT refined position\r\nor at the UVOT optical counterpart location (Evans et al.\r\nGCN 21413, Emery et al. GCN 21411) at the following\r\n3-sigma limits:\r\n\r\nr' > 21.4 mag\r\ni' > 21.1 mag\r\n\r\nThese magnitudes are calibrated against nearby USNO-B1 sources,\r\nconverted in SDSS bands, and not corrected for Galactic extinction.\"",
  "circularId": 21417,
  "createdOn": 1501952025000,
  "email": "antonino.cucchiara@uvi.edu",
  "subject": "GRB 170804A: LCO Observations",
  "submitter": "Antonino Cucchiara at UVI  <antonino.cucchiara@uvi.edu>",
  "eventId": "GRB 170804A"
}