left Hale-Bopp, 1997 March 19, blue filter, 40s of processed exposure time from a longer imaging session.
right Same image after digital unsharp mask subtracted.
Hale-Bopp, 1997 March 19, no filter, 7.5s of processed exposure time from a longer imaging session
Hale-Bopp, 1997 April 28, no filter, 4.87s of processed exposure time from a longer imaging session
Hale-Bopp, 1997 April 28, no filter, 4.17s of processed exposure time from a longer imaging session