Left panel: surface brightness in comet C/2006 W3 (Christensen) as a function of distance from the position of the center of the peak measured with PACS on UT 1.8 November 2009 (shown by the blue and red dots for the 70 μm and 160 μm bands with a pixel size of 3.̋2 and 6.̋4). Right panel: surface brightness radial profiles observed on UT 26.5 August 2010 (blue and red dots denote the 70 μm and 160 μm bands with projected pixel size of 1′′ and 2′′). The green crosses and circles are resampled profiles with 1′′ and 2′′ bins for the blue and red band images from November 2009, and 0.̋5 and 1′′ bins for the blue and red band images from August 2010. Error bars are 1σ statistical uncertainties.