TITLE:   GCN CIRCULAR
NUMBER:  33662
SUBJECT: GRB 230420A: LCOGT Optical Upper Limit
DATE:    23/04/20 23:21:17 GMT
FROM:    Robert Strausbaugh at University of Minnesota <rstrausb@umn.edu>

R. Strausbaugh (University of Minnesota), A. Cucchiara (NASA) report on
behalf of a larger collaboration:

We observed the GRB 230420A (Klingler et al., GCN 33658) field with the
LCOGT 1-meter Sinistro instrument at the Teide Observatory, Tenerife site,
on April 20, from 20:28 to 20:55 UT (corresponding to 11.15 to 11.72 hours
from the GRB trigger time) with the SDSS r and i filters.

We performed a series of 3x300s exposures in each band.  We do not detect a
source within the Swift-XRT enhanced error region (Osborne et al., GCN
33661) in either band.

The following upper limits are calculated using the PanSTARRS catalog as
reference:

r > 22.3
i > 21.8

These magnitudes are not corrected for galactic extinction.