{
  "bibcode": "2021GCN.29600....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 210306A (D'Elia et al., GCN 29597) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on March 6, from 06:49 to 07:06 UT (corresponding to 2.93 to 3.22 hours from the GRB trigger time) with the Bessel R and I filters.\n\nWe performed a series of 4x120s exposures in R and I. We clearly detect an optical source in R and I band in stacked images at a location consistent the initial UVOT detection (D'Elia et al., GCN 29597), in agreement with other optical afterglow detections (Watson et al., GCN 29598; Romanov, GCN 29599).  Using the USNO-B.1 catalog as reference, we calculate the following magnitudes:\n\nR = 19.00 +/- 0.02\n\nI = 17.70 +/- 0.03\n\nThese magnitudes are not corrected for galactic extinction.  The fainter R magnitude could indicate a moderately high redshift.\n\nR.S. is funded by NSF AST grant #1831682",
  "circularId": 29600,
  "createdOn": 1615016457000,
  "email": "robert.strausbaugh@uvi.edu",
  "subject": "GRB 210306A: LCO Optical Afterglow Detection",
  "submitter": "Robert Strausbaugh at U. of the Virgin Islands  <robert.strausbaugh@uvi.edu>",
  "eventId": "GRB 210306A"
}