Measured beam pattern. From upper left to lower right: beam maps of arrays A1 and A3, the combination of the 260 GHz arrays (A1 & A3) and the 150 GHz array (A2) are shown in decibel. These 10′ × 10′ maps, have been constructed from the normalised combination of four relatively long scans of bright point sources. Details on the structures present in the maps are given in the text.