Some follow-up on the M57 magnitude sequence: - The scope was collimated as well as it can be, and even got a nod of approval from Mike Spooner as he was evaluating my scope. There is a small amount of astigmatism brought on, I think, by the mirror cell, which may be deforming the mirror slightly. Collimation never takes more than a couple minutes with a laser at the beginning of the evening. I know that's not the problem with my star images, and it was good to have that confirmed by Mike. - I viewed M57 while it was still at an altitude greater than 60 degrees, which translates to less than 1.15 airmasses. Even if the extinction were really bad (which it was not that night), I wasn't losing more than a few tenths of a magnitude relative to a high-elevation site and viewing at the zenith. To make a reference back to the Halley recovery days of 1985, perhaps I would have done better atop Mauna Kea while taking bong hits of oxygen. - I wouldn't discount the notion that the presence of M57 is not helpful. While I can't say it was killing my dark adaptation, it was certainly distracting. Of course, you wouldn't get nearly as many people to do this sequence if it were not around a popular object such as the Ring Nebula. Tom --- This message is from the AZ-Observing mailing list. If you wish to be removed from this list, send E-mail to: AZ-Observing-request@xxxxxxxxxxxxx, with the subject: unsubscribe. The list's archive is at: http://www.freelists.org/archives/az-observing This is a discussion list. Please send personal inquiries directly to the message author. In other words, do not use "reply" for personal messages. Thanks.