TITLE:   GCN CIRCULAR
NUMBER:  32238
SUBJECT: GRB 220618A: iTelescope T-19 upper limit
DATE:    22/06/21 00:48:42 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

Y. Koyanagi, K. Hasuda, E. Kiuchi, N. Shimizu, T. Sakamoto (AGU)

We observed the field of GRB 220618A detected by Swift
(Troja et al., GCN Circ. 32214) with the iTelescope.Net
(http://www.itelescope.net) T19 (Planewave 17" CDK) telescope
located at the New Mexico Skies Observatory (NM, USA).
We took 10 images of 120 sec exposures in the Red filter
starting from June 18 at 09:46:36 (UT), about 0.6 hours after
the trigger and stopped at 10:09:40 (UT).

We do not detect the optical afterglow in the individual
images and the stacked image at the XRT position
(Osborne et al., GCN Circ. 32216). The estimated five sigma
upper limits of the combined image (total exposure of 1200 sec)
is 17.8 using the USNO-B1 catalog.