TITLE:   GCN CIRCULAR
NUMBER:  41310
SUBJECT: GRB 250809A: LCOGT Optical Upper Limits
DATE:    25/08/10 00:29:39 GMT
FROM:    Robert Strausbaugh at Eastern Illinois University <rstrausbaugh@eiu.edu>

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

We observed the Swift GRB 250809A field (Parsotan et al., GCN 41303)  with the LCOGT 1-meter Sinistro instrument at the Cerro Tololo Interamerican Observatory, Chile site, on August 9, from 23:10 to 23:42 UT (corresponding to 6.28 to 6.85 hours after the GRB trigger time) with the Bessel R and I filters.

We performed a series of 3x300s exposures in I-band and R-band.  We do not detect an uncatalogued source within the Prompt Swift XRT error region (Evans et al., GCN 41304) in either band.

The following 3-sigma upper limits are calculated using the USNO-B1.0 catalog as reference:

R > 20.6
I > 20.3

These magnitudes are not corrected for galactic extinction.