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Pushing the Limits

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#26 Starman1

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Posted 20 February 2013 - 08:55 PM

Starman1 posted:

Quote:

8) Seeing shadows of the festoons on the edge of an EQ Band on Jupiter

You're kidding, right?



Nope. On the same night as mentioned, the gray-green festoons hung out above the ocher-colored EB and were lined with dark edges only on one side. I finally realized that that was because the shadows of the festoons were cast on the clouds below, making the edges of the festoons black on one side. Each festoon looked not just like the typical swirl or arc, but a mottled bunch of cloud, sort of like the center of M42.
It was an uncanny night. I never saw that before and haven't seen it since. Could be I was seeing a darkish chemical in the atmosphere on the downwind side of each festoon instead of a shadow, but the white storms in the depths of the ocher EB did not show that, and some of them were being torn apart and appeared streaked in the downwind direction.


I have to take a little issue with the idea of a cloud "shadow". There are small linear bluish/dark grey clouds or features that hug the main belts and festoons, but these are thought to be either "clearings" in the upper cloud deck or actual bluish clouds rather than shadows. With Jupiter, any shadows cast by higher clouds would tend to fall almost directly beneath them when near disk center, so from Earth, they would be difficult to impossible to see since the sun is always behind us when viewing Jupiter. Clear skies to you.


Well, Jupiter was near quadrature, the festoons were obviously "hanging out over the edge" of the EB, which, from reading about it, is a lower cloud bank we see through the "parting" of the whitish higher-altitude cloud banks. The dark shadow was on the edge away from the sun but not on the sunward edge. And the dark edge of each festoon was thicker near the band it extended from and thinner as you went toward the 'tip". I called them festoons, but I think the correct Jupiter term is "projections".
They appear like bluish-green-grey "hooks" that extend out from a bright band into the ocher-colored EBs.
On this night, those "hooks" appeared mottled and a little flocculent and each one of them had a dark edge to one side, the side away from the sun. Like I said, it could be chemical in nature, and it might even be an illusion caused by color differences, but it sure looked like shadows.

#27 Astrojensen

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Posted 21 February 2013 - 03:38 AM

It takes me waiting for the [M81] galaxy to culminate and a really dark night. The "glow" of the spiral arms is usually there, but seeing the actual arms, I've found, is tough.


I've seen the brightest part of the eastern arm, the one starting near the two brightest foreground stars inside the disk of the galaxy, in a 6" refractor with binoviewer. It was surprisingly well visible. There are three HII regions in that section of the arm and I think it might be possible to see them in a 12", as they are very compact and have high surface brightness. In my 12" Lightbridge, I can faintly see the arm continue around the galaxy eastward, then north and finally in an elegant curve westward.


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#28 hbanich

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Posted 21 February 2013 - 03:48 PM

Howard,

Could you be more specific on where the knot in M51 is that you are talking about in your post.

Thanks


Hi Jimi,

I've circled it red at the top of the cropped HST image below. I've put more time into trying to detect this little goober than any other detail in M51, and so far no luck!

Attached Files



#29 Tom Polakis

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Posted 21 February 2013 - 04:35 PM

Some challenges for the 12.5", with some a LOT easier than others:


Nice list, Don. I'll go back to when I used a 13-inch as my primary scope to compare notes.

2) Seeing individual stars in NGC206 in M31. There are 6 superimposed stars in the Milky Way. If you see a dozen or more, you're picking up stars in M31. Mags 17.03-17.55


I know I've seen at least a dozen faint stars in this association, but I didn't realize they were that faint. When I did limiting magnitude checks with my 13-inch, I always stopped at around 17.


3) Seeing the spiral arms in M81
4) Seeing the spiral arms in NGC2403
5) Seeing the spiral arms in NGC7331


I remember how jaw dropping it was when I first saw the spiral structure in M81. After I knew what to look for, it was apparent every time in the 13-inch. NGC 2403 shows spiral structure, but its low galactic latitude corrupts the view with a lot of nearby field stars. And here I'm going to admit that I rushed over to Stephan's Quintet too often to really look for spiral structure in NGC 7331.

6) Seeing white swirls inside the Great Red Spot on Jupiter
7) Seeing albedo markings on Ganymede
8) Seeing shadows of the festoons on the edge of an EQ Band on Jupiter


Definitely have not seen 6 or 8, but have seen markings on Ganymede with my 10-inch at magnifications approaching 1000x. While it's a rewarding view, I wouldn't claim it's aesthetically pleasing!

9) Seeing 6 distinct galaxies in Hickson 92, aka "Stephan's Qunitet"


I have a hard enough time splitting the close pair to see five. Never thought to look for the detached one.

10) Seeing IC4617 on the outskirts of M13
11) Seeing IC1296 on the outskirts of M57
12) Seeing the central star in M57


I've seen IC 4617 and the central star in M57 in both my 13-inch and 10-inch scopes, but that galaxy near the Ring has required my 18-inch.


13) Seeing the G-H1-H2, and I stars in the Trapezium
14) Seeing the jet in M87
15) Seeing the "fingers" protruding from NGC5195 (companion of M51)



All good suggestions. I will admit that I've had difficulty with M87's jet in my 18-inch, and never saw it in repeated attempts with the 13-inch.


My hope is to add to this list to provide some year-round challenges for 10-12"+ apertures.


I'll look through my notes, and come up with some suggestions.

Tom

#30 LivingNDixie

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Posted 21 February 2013 - 04:45 PM

Tom (and others):
How hard are the features on Ganymede?

#31 Tom Polakis

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Posted 21 February 2013 - 10:47 PM

Tom (and others):
How hard are the features on Ganymede?


In my case, it's feature, singular. I have seen Galileo Regio, which is the giant, dark albedo feature that occupies the upper right part of the globe in this image.

Galileo Regio

Ganymede gets nearly as large as 2", so the feature is not much less than an arcsecond in size. When the seeing is good, use ludicrous magnification to see it.

WinJUPOS accurately shows which features on Ganymede are visible at any given time.

Tom

#32 Ptarmigan

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Posted 27 February 2013 - 04:33 PM

Thomas,
Not to nitpick but hurricanes actually don't purge the atmosphere of moisture after they pass. Been through a couple of hurricanes :(

But you are right dry skies with low humidity is good though :)


Hurricanes leave a lot of moisture behind.

#33 Dave Mitsky

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Posted 27 February 2013 - 09:18 PM

Actually, given its huge size, NGC 4236 should be visible in 10x50 binoculars. I've yet to do this, though. Conditions must be superb.


FWIW, NGC 4236 isn't mentioned in Phil Harrington's Touring the Universe through Binoculars. Then again, neither are NGC 5866 (M102) and NGC 5907. The only galaxy listed in Draco is NGC 4125. NGC 4236 and NGC 5907 are not included in the Astronomical League's Deep Sky Binocular Program. M102 is listed in the Tougher Messier Objects category of the Astronomical League's Binocular Messier Program Appendix B for 56 to 80mm binoculars.

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#34 azure1961p

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Posted 27 February 2013 - 09:48 PM

Don,
I'm utterly convinced that under 8/10 or better sky's and 500x Ganymede would be terrific in your scope. I don't think its a matter of possibility but of just how much detail. I wouldn't rule out 600x or more on the best nights as its very very small size seems to favor the enlargement typically reserved for diffraction pattern study. I know Norme with his 6" Mak found 80x per inch effective even though its be horrible on Jupiter itself. Spreading the light out of the tiny moon even beyond conventional experience seems to work well. 450x is great in my 8" but the bother of getting seeing to allow this in Connecticut is tough. Id like to try Norm 80x per inch suggestion but this winter never got past 7/10. I've found that while it had shown it is extraordinarily demanding. I get no lesser seeing compromises - its simply blank.

Preston, - harder than mars but easier than Pluto. ;)



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#35 tnakazon

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Posted 01 March 2013 - 01:38 AM

FWIW, NGC 4236 isn't mentioned in Phil Harrington's Touring the Universe through Binoculars. Then again, neither are NGC 5866 (M102) and NGC 5907. The only galaxy listed in Draco is NGC 4125. NGC 4236 and NGC 5907 are not included in the Astronomical League's Deep Sky Binocular Program. M102 is listed in the Tougher Messier Objects category of the Astronomical League's Binocular Messier Program Appendix B for 56 to 80mm binoculars.

Dave Mitsky

NGC 4236 and NGC 5907 are tough objects in a small telescope, especially 4236. Even though I don't use binoculars, I don't see them as binocular objects. Now NGC 5866 is easier to see using a small telescope in light-polluted conditions, so this would be more suitable for binoculars.

#36 Matt Lindsey

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Posted 02 March 2013 - 08:14 PM

Wait a minute Howard. Did you say detail within the jet of M-87??!!

#37 hbanich

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Posted 02 March 2013 - 11:00 PM

Wait a minute Howard. Did you say detail within the jet of M-87??!!


I saw a couple of the brighter knots in the jet with my 28 f/4 last April. They were subtle, slightly brighter areas along the jet that helped define the line of the jet. The seeing was so-so and the SQM was 21.68 at the time and I was using 695x.

It helped that I had seen M87's jet with several knots though the 90 inch Bok Telescope on Kitt Peak a few years ago, so I had an idea of what they might look like, but I was still surprised I could see even two of them in my own scope.

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#38 hbanich

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Posted 04 March 2013 - 01:12 AM

Just to make sure no one confuses the two galaxies at the top of the sketch with the jet, I've added labels:

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#39 Mta472

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Posted 05 March 2013 - 06:06 AM

You didn't see all of this from the LA area did you???

ole Mike

#40 Achernar

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Posted 05 March 2013 - 12:07 PM

I have glimpsed hints of surface features on Ganymede with the 15-inch, at 425X when the seeing was good. Namely the brighter polar regions versus the darker equatorial regions. I may have glimpsed the central star in M-57, the seeing here is just too poor most of the time for a large telescope to show it.

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#41 Achernar

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Posted 05 March 2013 - 12:12 PM

Indeed, they often flood more moisture into the area. I've rode out five of them since 1995, from Roaring Katrina and Ivan the Terrible to Troublesome Danny. The heat and dampness that followed could have been cut with a knife. Sometimes after a hurricane passes through, I do get some good stargzing in because power outages are very wide spread when a major hurricane hits anywhere near Mobile. The skies got very dark after Ivan and Katrina lashed Mobile.

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#42 Starman1

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Posted 05 March 2013 - 04:53 PM

You didn't see all of this from the LA area did you???

ole Mike

No, of course not. LA's night sky is orange! :bawling:
I travel to Mt. Pinos (8350') about 100 miles away, or Desert Center (850') about 200 miles away.
Mt. Pinos' night sky averages 21.3-21.4 mag/sq.arc-sec.
Desert Center's night sky averages 21.5-21.6 mg/sq.arc-sec.
[22.0 is as dark as it gets on Earth]
My backyard averages mag. 17.5-17.8, about like mid twilight in the dark sites.

#43 Astro One

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Posted 05 March 2013 - 08:58 PM

Amazing limits! I've been observing now for ten years. In the past three years I've been going out a lot to Red Cloud Rd and driving about 3.5 miles south of the freeway. Then I set up on the desert pavement, elevation about 1600.' Recently, on a good night, I got averaged SQM readings of 21.7. For this next new moon I am going to locate near Mesquite Springs, maybe in the campground, at Death Valley. For me the drive to the Red Cloud Rd site is just 99 miles. I look at a lot of eye candy, but am beginning to seek out more challenging targets.






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