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caheaton
super member
Reged: 05/26/09
Posts: 157
Loc: SW Ohio
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Hello, we finally had a decent night for viewing last night. Skies were clear, not particularly transparent (but about average for the Ohio valley and summer...could see stars to about mag 5) but the air seemed to be steady. My primary targets for the night were Jupiter's GRS and the North American Nebula (thought I'd give it a shot).
Despite some tracking problems and clutch slippage (last time this happened a new set of batteries cured the problem), I considered the observing session a success. First target for the evening was Jupiter, and upon using the 6.4EP and built in barlow a immediately noticed a tiny black spot near Jupiter's equator. I knew immediately what it was...Io's shadow! (Cloudy Night's software had indiciated that it would be visible, but I didn't really expect to resolve it with the little ETX.) I tried popping in a medium green filter and later my V-block, but tonight they didn't seem to offer much, as they seemed to hinder my views of the eclipse. Ironically, I never did see the GRS. Even though it's much bigger...it has remained elusive despite a lifetime of attempts.
My attempt at the North American Nebula likewise failed...even after trying my skyglow filters. Not really surprised, given the poor transparency and skyglow at my site, but I thought I'd give it a shot anyway. Some randow slewing did turn up a nicely colored reddish star about 2.5 to 3 degrees East of Altair.
Not much else going on last night, as the tracking errors interfered with my viewing, but that little shadow made my evening. Very impressive for that little scope, despite the fact that I've discovered that it has a little astigmatism (seems to be the objective lens and not the mirror, since adjusting the mirror slightly doesn't correct the issue, but it's still much less then what I have with my eyes so it's not a concern to me).
Just thought I'd post an update on what I've been doing with that little ETX....
Craig
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Treehopper
professor emeritus
Reged: 07/29/08
Posts: 582
Loc: Upstate NY
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Great catch, Craig! Must have had some decent seeing, if my math is right you were up around 125x! Not bad at all for a small scope!
If it's the diagonal mirror that's a little smudgy, you should be able to see it without an EP in place. I would imagine with a little care, minor dust or "goop" can come up with cotton swabs and some distilled water. If it's actually developed a thin spot in the mirror coating, that's another matter and would probably require some professional attention.
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Tim
Champion of small aperture scopes everywhere!
Meade ETX-125PE
Meade ETX-80
Celestron FirstScope 76mm Mini-dob
 Updated: 09/16/2009
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caheaton
super member
Reged: 05/26/09
Posts: 157
Loc: SW Ohio
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Thanks Treehopper...would a dirty mirror really cause me to have astigmatism? The mirror does need cleaning...it's been that way since it was purchased, but I just never got around to it. I have some alcohol (70% isopropyl) I use for the EP's, perhaps I should swab the mirror.
On a side note, I forgot to add that I also paid a visit to M31 and was able to clearly make out (though faint) M32 and M110 in the same FOV as M31. That was a first...never could have done it without this scope's wide FOV. (I used a 26mmEP for that one).
Also, my mysterious reddish star appears to be Gamme Aquilae...class K giant.
Craig
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Treehopper
professor emeritus
Reged: 07/29/08
Posts: 582
Loc: Upstate NY
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Of course, Craig, any attempt to clean or service any precision optical equipment comes with the caveat "proceed at your own risk." Nevertheless, with a modicum of care, there's no reason you can't have a go at it.
One of the more popular cleaning formulas (not sure if it's Dr. Clay's or originated somewhere else) is to mix three parts distilled water (many recommend running it through a filter anyway, just to be safe) with one part isopropyl alcohol, and one (and only one) drop of dish-washing detergent.
The water is the primary cleaning agent. The alcohol, due its lower evaporation point, will help dry the surface faster, and the dish-washing detergent serves as an emulsifier that will encourage evaporative "sheeting", which will prevent any streaking after it dries. Dob a clean swab into the mixture, blot it on a dust free cloth to prevent it from leaving large drops, then very gingerly apply it to the surface of the mirror. Keep a clean dry swab on hand just it case it does pool to keep it from dripping inside the instrument. Do not "scrub" or swipe the swab across the surface, just lightly dob a small area, then discard the swab and repeat with a fresh one.
So long as any dust, smudges, etc. are on the untreated glass side of the mirror, you should be safe. If you discover it's on the mirrored or "tinned" side, this is more problematic. I've heard of more adventurous souls than mine replacing the diagonal mirror themselves, but I sure wouldn't do it personally.
Good luck, Craig! 
Clear skies,
Tim
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Tim
Champion of small aperture scopes everywhere!
Meade ETX-125PE
Meade ETX-80
Celestron FirstScope 76mm Mini-dob
Updated: 09/16/2009
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rob0260
super member
Reged: 01/31/09
Posts: 116
Loc: Teulon, Mb., Canada
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Nice catch with the little 80 Craig. I tried viewing Jupiter with my little 80 but can't see much. It's very low at out latitude right now but climbing a bit more each night. Maybe I'll try again tonight.
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SN8, LXD75, ETX 80, 4 1/2 inch Newtonian, DSI-C, Meade series 4000 eyepiece set, Antares ub2s barlow, antares 5x barlow, 10x50 binoculars.
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