TITLE:   GCN CIRCULAR
NUMBER:  27646
SUBJECT: GRB 200425A: LCO Optical Upper Limits
DATE:    20/04/25 17:42:20 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 200425A (Bernardini et al., GCN 27638) with the LCO 1-m Sinistro instrument at the Siding Spring Observatory, Australia site, on April 25, from 08:26 to 09:07 UT (corresponding to 8.17 to 8.85 hours from the GRB trigger time) with the Bessel I and R filters.

We performed a series of 5x240s exposures in R and I. We do not detect any fading sources in the individual frames (or in stacked images) in the Enhanced Swift-XRT position region (Beardmore et al., GCN 27639).  Using the USNO-B.1 catalog as reference, we obtain the following 3-sigma upper limits:

R > 22.45

I > 21.96

These magnitudes are not corrected for galactic extinction.

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