Posts Made By: Kim Colter

Gary
Is it possible that you have two passions/obsessions? The first would be for a really large aperture scope and the second for a binocular scope. I own a 40 inch f5 Dob. It weighs about 800 pounds. Believe me, I cannot see how anybody would build a binocular scope in this aperture. If you undertake this, we need to get Wener Herzog, that German film maker who shot the movie about the guy who tried to drag a steamship through the Amazon jungle (titled Burden of Dreams, I think) to get your efforts down on celluloid. The binoviewer in a scope of this aperture is a much better idea.
As to f ratio, I also own a 20 inch Starmaster with the f4.3 mirror. Collimation is critical with these faster mirrors. I can't imagine the task of trying to keep two mirrors this fast collimated well with respect to focuser,secondary, and primary and then trying to keep the optical axes of these two big mirrors collimated well. More material for Werner Herzog, methinks.
If you must build a binoscope, how about keeping the aperture at around 11 or twelve inches and the f ratio at about 5?
You can get your "Aperture Jones" satisfied in cyclops mode with a scope in the 25 to 40 inch range I am sure, and the binoviewer in such a scope makes more sense to me than trying to construct the mother of all binoscopes.
As to the f ratio you choose for your large aperture scope, ask yourself how long a trailer or how big a roll off roof observatory you want to build. My 40 inch is in a roll off that is a room 24 feet by 24 feet. It tucks down on the diagonal axis of the building with inches to spare. (My observatory was built for a 30 inch f4 scope that now resides in our club's observatory about 3 miles away. I think we should be called the "Ozark Mauna Kea" with all due apologies to Michael Connelly and other real astronomers from the real Mauna Kea.) This scope was hauled in a trailer by a previous owner who had the ability to winch it in and out of a nearly 20 foot long trailer by himself. Maybe he's the guy we should have shot the movie of....
I hope I haven't seemed too flippant. I clearly suffer from a similar case of aperture fever. In my day job I find that the guy who drinks one case of beer a day takes reassurance in the fact that he knows a guy who occasionally drinks a case and a half in a day. To discover someone whose aperture fever is at least as bad as mine is comforting.
The minimum useful mag in my 40 inch f5 is the 160X produced by the 31 Nagler as predicted by Michael. The Coma cluster, following the Markarian chain, cruising around the Veil, at this magnitude can be magical.
Best of luck with the quest(s).

Best recollection of observations with 40 inch f5, rural location, NELM varies from 5.5 to 6.5 depending on transparency. Some of the more difficult observations were only possible when transparency was excellent.

1: Dust bands in M82 A
2: Spiral arms of M61 A
3: Equatorial dust band of NGC891 A
4: Spiral arms of M33 A
5: The obscuring cloud of M64 ("Black eye") A
6: Spiral arms of M51 A
7: Emission nebula, NGC604 in M33 A
8: Dust bands in NGC3556 A
9: Spiral arms of M99 A
10: One dust band in the Andromeda galaxy A
11: Spiral arms of M101 A
12: Equatorial dust band of NGC3628 (The one near M65/66) A
13: Two dust bands in the Andromeda galaxy A
14: Emission nebulae in the spiral arms of M101 A
15: Spiral arms of M100 A
16: Equatorial dust band of NGC4565 (Coma Berenices) A
17: "Bend" of galaxy NGC4656 (Canes Venatici) A
18: Spiral arms of NGC2403 A I see spiral structure, arms are not long in this galaxy
19: Spiral arms of NGC2903 A
20: Bridge between M51 and companion galaxy A for bridge, dust lane in bridge on a couple of occasions when very transparent and seeing allowed use of 400-500X

Bill
I have looked at M81 many times with 20" and 40" Dobs from reasonably dark skies. I have never seen UGC 5336 but I have never specifically looked for it. Your post has me intrigued and I will look for a clear night to try it with the 40 inch. M81 is ideally positioned in the wee small hours of the morning at present--clear nights are traditionally hard to come by in the Midwest in Nov/Dec but we have been fortunate of late.

This feat belongs in the Astromart forums hall of fame. The scope probably looked like it was pointed below vertical while making this image. It really looks like a tarantula in this image! This would seem to be the equivalent of seeing omega centauri from Toronto or M51 from the Falklands.

Lee
Is that what a Pell Grant means in Florida?

Inge
Thank you for your post. I don't feel burned out in the least, but have also struggled with the weather of late. Last night the Clear Sky clock predicted excellent observing conditions. Unfortunately a cloud bank predicted to be just south of my location covered us the entire night. I find this forum to be of great value. I am waiting for another opportunity to try for the UGC galaxy next to M81 mentioned in a previous post. WSP is coming up and may stimulate some conversation about the southern targets you have mentioned in Fornax, Eridanus, etc. I have never found your moderation of the forum to be heavy handed. I may test it with a post about thermal issues and atmospheric conditions in the early AM hours with larger reflectors.

Inge
We had a nice night Saturday. Prompted by your posting I looked at NGC6229 with the 40 inch f5. Individual stars were visible. I liked the view at 367X the best.
Kim

I think you will find that the helix is a somewhat dim object without an OIII filter and that it is greatly enhanced by the OIII. It is surprisingly large. The increase in what one sees with the OIII filter on the Helix rivals the increase one sees on the Veil with the same filter. The Helix may hold the distinction of being the largest planetary with an NGC number. It is certainly exceeded in subtended arc by some of the Abells and by Sharpless 2-216 in Perseus (100 arc minutes.) I have been unable to convincingly see Sh 2-216.

Mike
Thanks for the heads up. After reading your post I dashed outside last night and was able to spot Vesta with 14X100 binocs.

You guys would appreciate a look at the Veil through the 40 inch.