TITLE: GCN CIRCULAR NUMBER: 32803 SUBJECT: GRB 221009A: BOAO NIR detections DATE: 22/10/19 15:52:11 GMT FROM: Myungshin Im at Seoul Nat U mim@astro.snu.ac.kr

Myungshin Im, Gregory S.-H. Paek, Gu Lim, Hyeonho Choi, Sophia Kim (SNU), Hyun-Il Sung (KASI), Yuji Urata (NCU) on behalf of a larger collaboration

We observed the field of GRB 221009A (Swift detection: Dichiara et al., GCN 32632; Fermi GBM detection: Veres et al., GCN 32636), in J and K filters with the KASINICS instrument on the 1.8 m telescope of the Bohyunsan Optical Astronomy Observatory (BOAO), Korea. The observation started at 2022-10-18-11:34 (UT) or JD=2459870.98230324, taking a series of images for about 1.25 hrs.

We identify the afterglow in the KASINICS images, with a rough photometry of K ~ 18.6 AB mag. Further observations and analysis are being carried out to obtain more data and refine the photometry.

We thank the staff of BOAO for carrying out the observation.