GCN Circular 30673

Subject

GRB 210820A: LCO Optical Upper Limit

Event

Date

2021-08-21T16:05:02Z (5 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 30664Loading...
 
 ) 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 30664Loading...
 
 ) 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