Persistent dust jets at comet Hale-Bopp

Two different filters were used during the exposures in order to discriminate between the gas and the dust in the coma. The photo obtained through an ultraviolet optical filter (ESO Press Photo eso9726a) displays mainly the distribution of gaseous CN molecules in the coma, while that through a yellow-green (V) filter (ESO Press Photo eso9726b) mostly indicates the distribution of dust grains. Since the telescope followed the motion of the comet during the exposures, the images of the stars in the field are not completely round, especially in the CN-image.