{
  "bibcode": "2021GCN.29613....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 210307A (Ambrosi et al., GCN 29610) with the LCO 1-m Sinistro instrument at the Sutherland Observatory, South Africa site, on March 7, from 09:28 to 09:59 UT (corresponding to 0.60 to 1.18 hours from the GRB trigger time) with the Bessel R and I filters.\n\nWe performed a series of 4x240s exposures in R and I. We do not detect an uncatalogued optical source in either band in single frames, or in stacked images at a location consistent the initial XRT detection (Ambrosi et al., GCN 29610).  Using the USNO-B.1 catalog as reference, we calculate the following upper limits:\n\nR > 20.72\n\nI > 20.66\n\nThese magnitudes are not corrected for galactic extinction.\n\nR.S. is funded by NSF AST grant #1831682",
  "circularId": 29613,
  "createdOn": 1615124656000,
  "email": "robert.strausbaugh@uvi.edu",
  "subject": "GRB 210307A: LCO Optical Upper Limits",
  "submitter": "Robert Strausbaugh at U. of the Virgin Islands  <robert.strausbaugh@uvi.edu>",
  "eventId": "GRB 210307A"
}