PRIMARY Apply primary beam correction to an interferometer map (i.e. DIVIDE the input image by the primary beam). The primary beam is assumed to be a Gaussian. After this correction, the noise is increasing exponentially with the distance to the map center, and the resulting image has thus to be truncated at some radius. For the Plateau de Bure interferometer, the typical values of the FWHM primary beam is: 58" at 85 GHz (3.5 mm) 50" at 100 GHz (3 mm) 43" at 115 GHz (2.7 mm) 21" at 230 GHz (1.3 mm)