Hi Steve, et al > Hi William, et al; > > It is interesting that we get so few evenings of really great seeing and > yet, those stand out as some truly memorable nights. And a tad frustrating. About the last 20 times I have set my telescope up here in FH the seeing has been 3/10 or worse. I set up before dusk and leave the scope out all night. I generally come out 3-4 times during the night and just before dawn to see if the seeing has improved. And, yes, my wife has threatened me with physical injury for constantly waking her up in the middle of the night :) You are right though, the few nights of really great seeing are certainly memorable and make it all worthwhile. As Tom mentioned the > seeing is generally about 2 arcseconds down on the desert floor. > So the SAC > sites: Flatiron, Sentinel, our old sites: Table Mesa and Buckeye all > usually provided seeing around that value. Of course they were often much > worse. But, every once in a while, they steadied down and got > superb for a > couple of hours; everyone observing for that time got to see just how good > their telescope could perform at high power and how much detail they could > see when things were good. > So far I have had very little luck with great seeing at any of the local sites - Flatiron, Cherry Rd, AZ City, Vekol, Sentinel, Five Mile Meadow - so I watch DSOs instead of doubles. My best luck away from home was a random spot along the road to 4 Peaks a few miles off Beeline Hwy. The seeing was 6-7/10 from dark til I left about midnight. I had a 3.5" refractor that night and it produced images of Saturn that still stand out among the best I have seen even in much bigger scopes. The little refractor also does a terrific job on easy doubles. It is my favorite scope for wide doubles because it makes nice big Airy discs and the colorful ones like Albireo are simply spectacular. > Because my backyard observatory gets more use, I have been > fortunate enough > to have several evenings of good seeing there, also. I can > always tell when > powers above 250X are actually useful, then the seeing is good. This is > generally during twilight, as I recently reported and it > generally lasts 15 > to 20 minutes. I too have had most of my good luck with seeing at home, not counting my recent poor streak. The most memorable occasion was right at twilight, same as you reported. The seeing was a solid 8/10 for almost an hour and I saw 5 sharp craterlets in Plato and split doubles that I could not touch on normal nights. The one I remember best was Lambda Cyg which is a pretty tight pair with a fairly bright primary and much dimmer companion, maybe 0".7 or .8 separation and it was split clean with plenty of black in between the primary and secondary with a perfect, stable Airy disc and first diffraction ring around the brighter star. This was using a 10" D-K Cassegrain which shows Lambda Cyg as a wildly scintillating blob of fuzz in my average seeing of about 4/10. I mostly use a 5" refractor at home and that scope does make excellent images in my average seeing which scores about 5-6/10 in that scope. > > Several of the best times of steady seeing have been when there was a thin > cloud deck. We set up the scopes under pretty clear skies and some cirrus > clouds came in and some bullheaded soul kept observing....then he called > over to us to say "hey, get on Jupiter, it is really GREAT!". > > Many of the times that I have had both good seeing and good transparency > have been after midnight. The seeing has had time to steady down and the > transparency is still clear. Again, those are superb and > memorable nights. > It feels like the Milky Way is just past your finger tips. > > Hoping for more of that; > Steve Coe > > Author "Deep Sky Observing--The Astronomical Tourist" > Saguaro Astronomy Club website > www.saguaroastro.org > > Hoping for more of that too :) Regards, Bill Wood Fountain Hills, AZ -- See message header for info on list archives or unsubscribing, and please send personal replies to the author, not the list.