TITLE:   GCN CIRCULAR
NUMBER:  31518
SUBJECT: GRB 220117B: TARGET optical upper limit
DATE:    22/01/23 08:06:29 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

Y. Koyanagi, K. Hasuda, T. Sakamoto (AGU)

We observed the field of GRB 220117B detected by Swift
(Melandri et al., GCN Circ. 31468) with The AGU Robotic
Gravitational-wave Electromagnetic Telescope (TARGET)
equipped with the Veloce RH200 (20 cm OTA) and the large
format CCD camera (ATK11000) located at the Machida field
of Aoyama Gakuin University. 18 images of 60 sec exposures
were taken in the R filter starting from January 17
20:08:41 (UT) about 3.2 minutes after the trigger and
stopped on January 17 20:41:42 (UT). We do not detect the
optical afterglow both in the individual images and the
stacked image at the enhanced XRT position (Evans, et al.
GCN Circ. 31473).  The estimated five sigma upper limit of
the combined image (total exposure of 1080 sec)
is ~15.3 mag using the USNO-B1 catalog.