TITLE:   GCN CIRCULAR
NUMBER:  34667
SUBJECT: GRB230911C: LCOGT Optical Upper Limits
DATE:    23/09/11 20:58:29 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 230911C (Sonbas et al., GCN 34655) field with the LCOGT 1-meter Sinistro instrument at the South African Astronomical Observatory site, on September 11, from 17:20 to 17:52 UT (corresponding to 8.55 to 9.08 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 (Evans et al., GCN 34658) in either band.

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

r > 21.6
i > 21.1

These magnitudes are not corrected for galactic extinction.