TITLE: GCN CIRCULAR NUMBER: 19584 SUBJECT: GRB 160623A: SMA submm afterglow observations DATE: 16/06/26 05:02:28 GMT FROM: Yuji Urata at Nat. Central U. Yuji Urata (NCU/ASIAA), Kuiyun Huang (NTNU), and Glen Petitpas (SMA/SAO) report: We observed the GRB 160623A afterglow (Mingo et al. GCN 19558, Butler et al. 19567) with Submillimeter Array (SMA) on 2016/06/24 (1.1 day after the Fermi-GBM trigger) and 2016/06/25 (2.2 day). The quick look image at the 1st epoch shows the bright (~15 mJy) submm afterglow. The source also shows a gradual fading at the 2nd epoch (corresponding decay index of ~-0.4). Further observation is ongoing. We thank the staff of SMA.