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General Astronomy >> General Observing and Astronomy

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azure1961p
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How good is your BEST seeing? new
      #5834175 - 05/01/13 11:42 AM

If you had to estimate your best arc second resolution on those rare nights what would it be? I have an 8" as my biggest scope but I can clearly estimate about 0.35" arc sec res from the clarity and stability of sub arc second doubles, tiny moons and the like. On those night 0.576 res isn't fringey and sporadic so .35 is a fair estimate. That's in Connecticut and ever when its hot out. Even challenging Connecticut sky's Im positive exceeds 0.5 and possibly a c14 for example would hit its res mark.

What would you guess yours is for your location real or estimated?

Thanks.

Pete

Edited by azure1961p (05/01/13 11:51 AM)


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: How good is your BEST seeing? new [Re: azure1961p]
      #5834235 - 05/01/13 12:14 PM

Gosh, Pete, best I have done is 0.74" (as reported) arc with a dark space. Not too difficult, pretty distinct dark space.

http://www.cloudynights.com/ubbthreads/showflat.php?Cat=0&Board=double&am...

It's something less than the theoretical Dawes for a 6", closer to Dawes for a 6" ~30% obstructed. I think I can get deeper (closer to 0.7" arc) if I can find the right target (nearly equal bright pair.)

My best seeing? I have had 10/10 more than once in 30 years. I dunno, average about 8/10 near the zenith with 9 and 10/10 not terribly uncommon. Sometimes less than that, too, around 6 to 7/10. But, about 8/10 on average and frequently enough, it's better.

Edited by Asbytec (05/01/13 12:33 PM)


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David Knisely
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Re: How good is your BEST seeing? new [Re: azure1961p]
      #5834369 - 05/01/13 01:12 PM

There have been a few rare times where I could see the diffraction patterns of stars in my 14 inch, so that would mean a seeing level of around 0.3 arc seconds. More typically, in our area it is more like one to three arc seconds with frequent moments where it gets down just a little under an arc second. Clear skies to you.

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azure1961p
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Re: How good is your BEST seeing? new [Re: David Knisely]
      #5834455 - 05/01/13 01:47 PM

Thanks guys. Its a projection to be sure on my part to state 0.35 but on those nights its only because the patterns were so calm. Norme with your nutty good seeing in the P- Isl's I'd bet you've easily had .35" - though granted through a smaller apertures Rayleigh as with me. David Im glad to see you've gotten it. I don't doubt that it eventually visits most everyone at one time or another and of course you've got the mirrors to realize it when it arrives.

An off shoot of this queried post might be: what's the highest useful magnification used on ______? The conventional wisdom is the seeing caps it at 500x but I kno of some reliable observers profitably using up to 700x on Ganymede for example. Jeff Beish comes to mind with his 16" in Florida. I think Stephen J Omeara was there that night to commenting on the perfect Ganymede image.

Side track over.

Thanks

Pete


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Asbytec
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Re: How good is your BEST seeing? new [Re: azure1961p]
      #5834464 - 05/01/13 01:51 PM

Pete, I may have had 0.35" arc seeing, but not sure how I could have known so in a 6". Side track, I have used over 100x per inch when star testing (looking or astig) and collimation. Nice, intact patterns, but a little dim.

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azure1961p
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Re: How good is your BEST seeing? new [Re: Asbytec]
      #5834477 - 05/01/13 01:56 PM

Dang your up late! A little Saturn observing?

Pete


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REC
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Reged: 10/20/10

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Re: How good is your BEST seeing? new [Re: azure1961p]
      #5835770 - 05/02/13 08:13 AM

Ok, how do you determine what arc seconds or minutes are that you can see. I guess I don't understand the definition of arc is?

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Asbytec
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Re: How good is your BEST seeing? [Re: REC]
      #5835952 - 05/02/13 10:19 AM

If seeing is 8/10, I estimate seeing to be at the Raleigh limit of the aperture then fudge from there, if necessary. Maybe if you can split 1.2" arc double, barely, then that's how you can tell. Normally, Pickering or Antionadi scales are fine. That's hwo I do it, good question though.

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David Castillo
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Reged: 09/09/06

Loc: Carmel Valley, Ca
Re: How good is your BEST seeing? new [Re: Asbytec]
      #5837171 - 05/02/13 08:22 PM

Ray Charles has a better view at his site than I've got at mine.
----
Dave


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herrointment
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Re: How good is your BEST seeing? new [Re: David Castillo]
      #5837370 - 05/02/13 10:24 PM

Once the seeing was so good I could actually collimate my sct. Yep, I was pretty excited.

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Cotts
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Reged: 10/10/05

Loc: Toronto, Ontario
Re: How good is your BEST seeing? new [Re: herrointment]
      #5837394 - 05/02/13 10:40 PM

Everyone gets 'perfect' seeing occasionally. The real question is "how often"?

I can see the diffraction pattern of stars in my 66mm refractor virtually every night that I try. In the 80mm almost every night. The 6" and 8" less often - perhaps 50% of the nights they are in use. I have only seen the diffraction pattern in my 16" (implying 0.25" seeing) from the Florida Keys - never at home...

Seeing is so variable, on timescales from <1 second to months and geographically from 'micro' (better over my lawn than over my roof) to 'macro' (better in the Florida Keys than in the Great Lakes region) that it is almost pointless to try to come up with any empirical guidelines to predict it .

Dave


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csrlice12
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Re: How good is your BEST seeing? new [Re: Cotts]
      #5837811 - 05/03/13 08:39 AM

One night early this winter, a few weeks after Christmas, I had four bands easily on Jupiter from my white zone back yard using the 102XLT. Normally it's only two with sometimes a third waving in and out. Weather has been terrible here in Denver this year.

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David PavlichAdministrator
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Reged: 05/18/05

Loc: Mandeville, LA USA
Re: How good is your BEST seeing? new [Re: csrlice12]
      #5837822 - 05/03/13 08:44 AM

Summertime brings very stable skies for the Gulf south. However, the transparency is the pits.

David


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