{
  "bibcode": "2020GCN.26630....1S",
  "body": "R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:\n\nWe observed Swift GRB 191228A (Barthelmy et al., GCN 26601) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on December 28, from 00:59 to 01:31 UT (corresponding to 0.66 to 1.22 hours from the GRB trigger time) with Bessel R and I filters.\n\nWe performed a series of 5x180s exposures in both bands. We do not detect any sources in the individual frames (nor in 5 stacked images in each band) in the enhanced Swift error region (Barthelmy et al., GCN 26607).  Using the USNO-B.1 catalog as reference, we obtain the following 3-sigma upper limits:\n\nR > 14.69\nI > 14.79\n\nThe low limiting magnitudes are most likely due to high sky background in the images in both bands.",
  "circularId": 26630,
  "createdOn": 1577967754000,
  "email": "robert.strausbaugh@uvi.edu",
  "subject": "GRB 191228A: Early Optical Upper Limits from LCO",
  "submitter": "Robert Strausbaugh at U. of the Virgin Islands  <robert.strausbaugh@uvi.edu>",
  "eventId": "GRB 191228A"
}