TITLE: GCN CIRCULAR NUMBER: 9100 SUBJECT: GRB 090404: millimeter detection DATE: 09/04/06 22:15:32 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia A. J. Castro-Tirado (IAA-CSIC Granada), M. Bremer and J.-M. Winters (IRAM Grenoble), J. Gorosabel, S. Guziy, M. Jel�nek, P. Kub�nek (IAA-CSIC), A. de Ugarte Postigo (ESO Santiago) and D. P�rez-Ram�rez (Univ. de Ja�n), report: "Following the detection by Swift of GRB 090404 (Ziaeepour et al. GCNC 9086), millimeter observations were conducted on Apr 5.9 UT at the Plateau de Bure Interferometer. Consistent the Swift/XRT enhanced position (Beardmore et al. GCNC 9088) we clearly detect a millimeter source with a 108 GHz flux density of 1.1 mJy at coordinates RA(2000) = 15:56:57.52, Dec(2000) = +35:30:57.5 with (0.3",0.2") 1-sigma error in (RA,DEC). Pending of confirming its variability we propose this as the likely millimeter afterglow to GRB 090404. Together with the lack of optical and near-IR afterglows (Xin et al. GCNC 9090, Yock et al. GCNC 9092, Malesani et al. GCNC 9095, Afonso et al. GCNC 9096, Jel�nek et al. GCNC 9099), this event strongly resembles the dark burst GRB 051022 (Castro-Tirado et al. 2007, A&A 475, 101). Further millimeter observations are scheduled." This message can be quoted.