GRB 221009A: NOEMA mm detection

We observed the afterglow of GRB 221009A (Dichiara et al., GCN 32632; Kennea & Williams, GCN 32635; Bissaldi et al., GCN 32637; Veres et al., GCN 32636; Lesage et al., GCN 32642) with NOEMA at 90 and150 GHz starting at 16:32 UT of the 10th of October, (27.35 hr after the Fermi GBM trigger; Veres et al., GCN 32636). The afterglow is strongly detected at 90 GHz with a flux of ~15 mJy. This is significantly below the extrapolation of the data reported at lower frequencies in previous GCNs (Bright et al. GCN 32653; Farah et al., GCN 32655), indicating that our observations are beyond the peak Frequency, and that the earlier observations may have been affected by a reverse shock that has already faded.