GCN Circular 30673
Subject
GRB 210820A: LCO Optical Upper Limit
Date
2021-08-21T16:05:02Z (3 years ago)
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 210820A (Beardmore, et al., GCN 30664) with the LCO 1-m Sinistro instrument at the Teide Observatory, Tenerife site, on August 21, from 01:20 to 01:51 UT (corresponding to 7.7 to 8.5 hours from the GRB trigger time) with the Bessel R and I filters.
We performed a series of 5x120s exposures in R and I. In the UVOT detection region (Beardmore, et al., GCN 30664) no optical counterpart could be detected down to the following upper limits, calculated using the USNO-B.1 catalog as reference:
R>20.16
I>19.17
These magnitudes are not corrected for galactic extinction.
R.S. is funded by NSF AST grant #1831682