TITLE:   GCN CIRCULAR
NUMBER:  29829
SUBJECT: GRB 210419A: LCO Optical Upper Limit
DATE:    21/04/19 15:40:31 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 210419A (Laha, et al., GCN 29828) with the LCO 1-m Sinistro instrument at the Siding Spring Observatory, Australia site, on April 19, from 08:33 to 08:57 UT (corresponding to 1.67 to 2.1 hours from the GRB trigger time) with the Bessel R and I filters.

We performed a series of 4x180s exposures in R and I. We do not detect any uncatalogued optical source in the coadded images within the XRT error region (Laha, et al., GCN 29828).  Using the USNO-B.1 catalog as reference, we calculate the following upper limits:

R>21.91

I>21.16

These magnitudes are not corrected for galactic extinction.

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