TITLE:   GCN CIRCULAR
NUMBER:  34834
SUBJECT: GRB 231017A: LCOGT Optical Upper Limits
DATE:    23/10/18 20:47:26 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 Fermi GRB 231017A field (Fermi GBM team, GCN 34822) with the LCOGT 1-meter Sinistro instrument at the Teide Observatory, Tenerife site, on October 18, from 01:01 to 01:34 UT (corresponding to 15.93 to 16.48 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 error region around the candidate X-ray source (Dichiara et al., GCN 34829) in either band.

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

r > 23.0
i > 22.6

These magnitudes are not corrected for galactic extinction.