TITLE:   GCN CIRCULAR
NUMBER:  38605
SUBJECT: GRB 241218A: LCOGT Optical Upper Limit
DATE:    24/12/18 04:35:43 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 241218A field (Williams et al., GCN 38601)  with the LCOGT 1-meter Sinistro instrument at the Teide Tenerife site, on December 18, from 03:45 to 04:17 UT (corresponding to 3.62 to 4.15 hours after the GRB trigger time) with the sdss r and i filters.

We performed a series of 3x300s exposures in i-band and r-band.  We do not detect a source within the Swift XRT enhanced error region (Beardmore et al., GCN 38604) in either band.

The following 5-sigma upper limits are calculated using the PanSTARRS catalog as reference:

r > 21.2
i > 20.9

These magnitudes are not corrected for galactic extinction.
