TITLE: GCN CIRCULAR NUMBER: 11304 SUBJECT: GRB 100925A/MAXI J1659-152: Submm observations from APEX DATE: 10/09/26 01:51:55 GMT FROM: Antonio Deugarte at IAA-CSIC A. de Ugarte Postigo (Dark/NBI), A. Lundrgren (ESO), F. Wyrowski (MPIfR), C.C. Thoene (NBIA), A. J. Castro-Tirado, J. Gorosabel, M. Jelinek (IAA-CSIC) report on behalf of a larger collaboration: "We observed the field of GRB 100925A/MAXI J1659-152 (Mangano et al. GCNC 11296, Negoro et al. ATel 2873, Barthelmy et al. GCNC 11300), a burst with possible Galactic origin (Kann GCNC 11299, Xu GCNC 11303), using LABOCA/APEX at Chajnantor (Chile) in the 870 micrometer band. Observations began on September 25th at 23:30 UT (15.5 hours after the burst onset). In a preliminary analysis we detect emission at the position of the optical afterglow (Marshall et al., GCNC 11298, Jelinek et al., GCNC 11301, De Cia et al. GCNC 11302) at a flux of 12.6+/-2.4 mJy."