Dust morphology of comet Hale-Bopp (C/1995 O1): i. Pre-perihelion coma structures in 1996

In 1996 comet Hale-Bopp exhibited a porcupine-like coma with straight jets of dust emission from several ective regions on the nucleus. The multi-jet coma geometry developed during the first half of 1996. While the jet orientation remained almost constant over months, the relative intensity of the jets changed with time. By using the embedded fan model of Sekanina and Boehnhardt (1997a) the jet pattern of comet Hale-Bopp in 1996 can be interpreted as boundaries of dust emission cones (fans) from four - possibly five - active regions on the nucleus (for a numerical modellung see part II of the paper by Sekanina and Boehnhardt, 1997b)