TITLE: GCN CIRCULAR NUMBER: 28033 SUBJECT: GRB 200623A : SMA observations at Swift/XRT Source #3 DATE: 20/06/26 07:19:35 GMT FROM: Yuji Urata at Nat. Central U. Kuiyun Huang (CYCU), Yuji Urata (NCU), Glen Petitpas (CfA) report We used SMA to observe the location of the Swift/XRT source #3 (Evans, GCN Circ. 28015) as one of the afterglow candidates of GRB200623A (Fermi/GBM Team, GCN Circ. 28011; DeLaunay et al., GCN Circ. 28013, 28016). The 230 GHz observation was started at ~1 days after the burst. No clear submm source at the Swift/XRT sources #3 position was found brighter than ~1 mJy. We thank the staff of SMA.