Domerman
Just Lucky, I Guess.
Reged: 07/21/07
Loc: PA
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Cassini divison?
#5294147 - 06/28/12 11:32 PM
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These past two days are the first times I seriously tried to view Saturn and actually tried for the famed Cassini division and it's a lot harder than expected! I'm using my C11 and with 200x I finally spotted it as a thin, arced sliver of black darkness on both sides of the rings. After careful collimation, I again spotted it momentarily at 509x. Why is it so difficult for me? I've seen people here say they easily spot it with 80mm refractors. Why am I having so many issues?! I'm sure my collimation is accurate and my optics are clean.. I am using Meade series 5000 plossls..not the best, but ok for plossls. I let the tube cool for several hours before-hand and even had my fans running for quite a while. Focus is good with the feather touch... Any opinions?
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starrancher
Carpal Tunnel
Reged: 06/09/09
Loc: Northern Arizona
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Re: Cassini divison?
[Re: Domerman]
#5294227 - 06/29/12 12:49 AM
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Quote:
These past two days are the first times I seriously tried to view Saturn and actually tried for the famed Cassini division and it's a lot harder than expected! I'm using my C11 and with 200x I finally spotted it as a thin, arced sliver of black darkness on both sides of the rings. After careful collimation, I again spotted it momentarily at 509x. Why is it so difficult for me? I've seen people here say they easily spot it with 80mm refractors. Why am I having so many issues?! I'm sure my collimation is accurate and my optics are clean.. I am using Meade series 5000 plossls..not the best, but ok for plosslIs. I let the tube cool for several hours before-hand and even had my fans running for quite a while. Focus is good with the feather touch... Any opinions?
Seeing conditions are everything here . Transparency isn't that important but a stable atmospheric condition is . I'm out now catching glimpses of it in my 60mm Tasco 7te . At 91x magnification . With current seeing , upping the magnification goes nowhere . If the seeing improves I'll bump it up a bit .
The 10mm Plossl I'm using is an Owl Plossl . About a twelve dollar ocular . So if I can grab that thing with what I'm using tonight surely you can grab it too ,
Though my seeing can be different from yours even if you were around the corner from me . If it was a warm day and you are viewing over rooftops that are still cooling down or set up on concrete or asfalt , this would be something that can make or break your view . Seeing seems it was better a couple years ago . Lately it seems its hard to catch a good night with stable skies .
Less magnification is my answer when seeing stinks . The more stable the sky the more you can effectively bump up the mag .
Try say 120x to 160x or there abouts . Crisper image maybe ?
Sometimes dropping the mag will do the trick .
Patience at the eyepiece , waiting for those moments of stable air pockets and the detail pops . A few seconds here and there over a period of minutes can be rewarding . Some nights the seeing isn't worth setting up for . Others are grand all night . On average nights , it's just a matter of patience and getting the best magnification for the givin seeing conditions .
That C11 will knock your socks off once you see the thing under the conditions that seem to be more far and few lately . Then 400x or 500x or 600x . I was able to hit 381x with my 8 inch on two grand nights in a row a couple years ago (4years ?) and haven't seen it like that since . Awesome tri color image in the disc and rings , Cassini with complete staying power and 6 moons . A memorable couple of Saturn nights . You don't get it that way all the time .
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Domerman
Just Lucky, I Guess.
Reged: 07/21/07
Loc: PA
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Re: Cassini divison?
[Re: starrancher]
#5294259 - 06/29/12 01:24 AM
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Thanks for the tips! I figured it was the seeing conditions, but the air didn't seem too turbulent in my star tests and clearsky reported average seeing. Saturn was fairly high in the sky above the tree tops. Although, I didn't give it much of a view in any power below 200, so perhaps the gap was more visible in lesser powers and I just didn't care to use those powers..  I want to try with my 80ED tomorrow, but looks like I'll be rained out. 
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Domerman
Just Lucky, I Guess.
Reged: 07/21/07
Loc: PA
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Re: Cassini divison?
[Re: starrancher]
#5294263 - 06/29/12 01:27 AM
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Nevertheless, I enjoyed seeing the Cassini division for the first time with my scope! I saw it for the very first time ever through someone's bino'ed scope a few days back, which was really cool. Very 3D affect. Now I'm hooked on catching the finer details in Saturn!
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MikeBOKC
Post Laureate
Reged: 05/10/10
Loc: Oklahoma City, OK
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Re: Cassini divison?
[Re: Domerman]
#5295099 - 06/29/12 04:07 PM
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Seeing for sure. A couple of weeks ago I aimed my CPC1100 at Saturn and Cassini popped out like a gap you could drive a truck through. A week later, same scope, same eyepiece, same time of night, it was barely visible if at all. For planetary detail, once you pass a certain aperture (I would say 8 inches) it's pretty much all about seeing.
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azure1961p
Postmaster
Reged: 01/17/09
Loc: USA
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Re: Cassini divison?
[Re: MikeBOKC]
#5295497 - 06/29/12 09:02 PM
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Sounds like seeing or a warm scope. Next time blow a fan on the OTA as its cooling. Can speed things along and assure a good equilibrium.
Cassinis is a finicky feature. Unlike the EQ belts of jupiter that show in almost all seeing, Cassinis needs its own particular conditions and its sheer frustration if you dont take it into account.
Good news, under better conditions a C11 wont just show a line but a true gap of varying width. Id seriously consider getting a Lymax cooling system for your cat.
Pete
Edited by azure1961p (06/29/12 09:03 PM)
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Domerman
Just Lucky, I Guess.
Reged: 07/21/07
Loc: PA
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Re: Cassini divison?
[Re: azure1961p]
#5295597 - 06/29/12 10:10 PM
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My CAT is cooled with two fans installed on both sides of the visual back. I tried to look for the divison again tonight with my 3" scope, but the skies are awful thanks to oppressive heat here in Philly. The moon was covered in a thick haze. Oh well.
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azure1961p
Postmaster
Reged: 01/17/09
Loc: USA
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Re: Cassini divison?
[Re: Domerman]
#5295662 - 06/29/12 11:14 PM
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Then its just a seeing thing. Youll see it soon enough in better conditions.
It CAN be frustrating when it doesnt pop.
Pete
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Domerman
Just Lucky, I Guess.
Reged: 07/21/07
Loc: PA
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Re: Cassini divison?
[Re: azure1961p]
#5295686 - 06/30/12 12:04 AM
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I'll have to see it with my ETX 90 then. I'm going back to my studies in Louisiana. I was only in Philly for a short break with my family. Now I must leave my 11" scope for another 8 months or so. 
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Kon Dealer
professor emeritus
Reged: 01/05/11
Loc: Cambridge UK
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Re: Cassini divison?
[Re: Domerman]
#5295947 - 06/30/12 07:11 AM
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Saturn is now too low in the sky for me.
Just scrapes above the surrounding houses.
The heat shimmer from the roofs has to be seen
to be believed 
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