TITLE: GCN CIRCULAR NUMBER: 22303 SUBJECT: GRB 180102A AROMA-N optical observation DATE: 18/01/06 00:57:23 GMT FROM: Takanori Sakamoto at AGU Y. Kitaoka, T. Sakamoto (AGU) We observed the field of GRB 180102A detected by Swift (Page et al. GCN circ. 22292) with the 0.3 m AROMA-N telescope located at Aoyama Gakuin University (Sagamihara, Japan). 10 images of 60 sec exposures were taken in the R filter starting from January 2 on 15:52:26 (UT) about 3 minutes after the trigger and stopped on 16:04:28 (UT). We do not detect the optical afterglow both in the individual images and the stacked image at the location of the X-ray afterglow (Beardmore et al. GCN circ. 22294). The estimated five sigma upper limit is ~16.0 mag using the USNO-B1 catalog.