Well, glass will start getting made for ~30m telescopes soon, and 100m telescopes are on the (digital) drawing boards. Since H-B still has a 6" coma at 21 AU from the Sun (detectable in an 8-inch telescope, mind you), it's obviously still active, and might still be when it gets out farther. Aphelion is at a few hundred AU, something like that, right? \Brian -- See message header for info on list archives or unsubscribing, and please send personal replies to the author, not the list.