The C/2006 M4 SWAN was a real treat for me and for other northern observers. It was a wonderful comet with very thin, faint long tail. I remember that it was moving very fast. Motion of comet was easily visible in eyepiece after 5 minute of observation. Head of this comet was bright and teal in color. To this date, this is most beautiful comet I've observed. I have managed to observe comet on for occasions using  my faithful  200 mm F6 Dobsonian. Comet was also a excellent test for my brand new Hyperion Eyepiece.