Gas and dust jets in the inner coma of comet Halley

Cyanogen (CN) jets were discovered in comet Halley by applying an image processing ring masking technique to ground-based observations^1,2. We now report the detection of dust, C₂, C₃, CN and ([O I] + NH₂) jet features in comet Halley during the period of the spacecraft Giotto encounter (13-18 March 1986). With absolute flux measurements, careful continuum subtraction and an improved ring-masking technique, we have achieved an unambiguous separation of the gas and dust components of the cometary coma emissions. A comparison of the morphologies of these gas and dust jets provides important information about the anisotropic dynamical processes in the cometary coma and on the surface of comet Halley's nucleus.