TITLE:   GCN CIRCULAR
NUMBER:  27337
SUBJECT: GRB 200306C: LCO Optical Upper Limits
DATE:    20/03/07 07:28:15 GMT
FROM:    Robert Strausbaugh at U. of the Virgin Islands  <robert.strausbaugh@uvi.edu>

R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:

We observed Swift GRB 200306C (Gropp et al., GCN 27326) with the LCO 1-m Sinistro instrument at the Cerro Tololo Interamerican Observatory, Chile site, on March 7, from 4:50 to 5:21 UT (corresponding to 6.0 to 6.5 hours from the GRB trigger time) with the Bessel I and R filters.

We performed a series of 5x120s exposures in I and R. We do not detect any sources in the individual frames (nor in stacked images) at the location of previous optical afterglow detections (Lipunov et al., GCN 27325, Jelinek et al., GCN 27328, Castro-Tirado et al., GCN 27329, Moskvitin et al., GCN 27333, Izzo et al., GCN 27334, Kann et al., 27335).  Using the USNO-B.1 catalog as reference, we obtain the following 3-sigma upper limits:

R > 20.56

I > 19.65

R.S. is funded by NSF AST grant #1831682