TITLE:   GCN CIRCULAR
NUMBER:  33217
SUBJECT: GRB 230123A: LCOGT Optical Upper Limits
DATE:    23/01/24 17:19:20 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 230123A (Williams et al., GCN 33206) field with the
LCOGT 1-meter Sinistro instrument at the Cerro Tololo Interamerican
Observatory, Chile site, on January 24, from 02:06 to 02:38 UT
(corresponding to 15.78 to 16.32 hours from the GRB trigger time) with the
Bessel R and I filters.

We performed a series of 3x300s exposures in each band.  We do not detect a
source in either band within the XRT enhanced error region (Beardmore et
al., GCN 33209), consistent with other optical upper limits (Gendre et al.,
GCN 33208; Belles et al., 33211).

The following upper limits are calculated using the USNO-B1.0 catalog as
reference:

R > 20.8
I > 20.1

These magnitudes are not corrected for galactic extinction.