TITLE: GCN CIRCULAR NUMBER: 9321 SUBJECT: GRB 080913: 250 GHz upper limit for a z=6.7 GRB with MAMBO-2 at the IRAM 30m DATE: 09/05/04 18:16:48 GMT FROM: Dominik A. Riechers at Caltech D. A. Riechers (Caltech), F. Walter (MPIA Heidelberg), F. Bertoldi (AIfA Bonn), C. L. Carilli (NRAO), P. Cox (IRAM) report: "We used the Max-Planck-Millimeter Bolometer (MAMBO-2) array at the IRAM 30-m telescope to observe the field of view toward the host galaxy of GRB 080913 (GCN 8217) at redshift z=6.7 (GCN 8225), RA 04:22:54.74, Dec -25:07:46.2 (J2000) at 250 GHz. Observations were carried out for 3.7 hr between 2008 November 13 and 15. We obtained a non-detection of S_nu(250 GHz,1.20 mm) = 0.34 +/- 0.45 mJy (1 sigma error), i.e. a 3 sigma upper flux density limit of 1.35 mJy on the dust continuum in the GRB host galaxy at 1.2 mm (rest-frame 156 um). The 117-element MAMBO-2 bolometer detectors cover 210-290 GHz (half power). The bolometers have a FWHM beam size of 10.7 arcsec, at a pixel spacing of 20 arcsec. Observations were carried out in ON-OFF observing mode under good weather conditions. Calibrations were performed on J0348-278 and J0609-157. We acknowledge the excellent support of the staff at IRAM. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). This message may be cited."