GCN Circular 29144

Huang, K. (CYCU), Urata, Y. (NCU) and Petitpas, G (SAO). report:

We observed the field of the GRB201221D (Page et al., GCN #29112) at
228 GHz using the Submillimeter Array (SMA).  The observation was
started at 2020 December 11:27 UT (12.3 h after the burst).  There was
no source at the candidate of optical afterglow (Malesani et al., GCN
#29117; Dichiara et al., GCN #29128; de Ugarte Postigo et al., GCN
#29132; Kilpatrick et al., GCN #29133; Rastinejad et al. GCN #29142).
The preliminary limit of the observation is ~0.2 mJy (rms).

We thank Ramprasad Rao, Mark Gurwell and staff of SMA for the
scheduling and execution of observations.