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Stephan's Quintet - what aperture needed?

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#26 Starman1

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Posted 14 August 2007 - 12:28 AM

I think Astronomy Magazine, 2006 Collector's Edition, entitled "Explore the Universe" summed it up quite nicely:

Simply seeing Stephan's Quintet (NGC 7317, NGC 7318A, NGC 7318B, NGC 7319, and NGC 7320) is not a challenge. You can glimpse the brightest, NGC 7320 in an 8-inch telescope. Differentiating the galazies' sizes, shapes (3 are spirals, 2 are ellipticals), and brightness, however, requires at least a 16 inch telescope.



Just another reason to get that 20" Obsession I have been obsessing over for the last year or two... :help:

Tim

Astronomy's summary may be correct when viewing in typical, suburban, moderately light-polluted sites. But they are wrong when viewing at a truly dark site. All of them are visible as smudges in a 6" refractor, and at least 4 are visible in 8" (the close pair is unresolvable). In my 12.5", at 203X, 6 discrete galaxies are visible, and so are their orientations on the sky.
A 16" begins to show details in all of them.
Many observing books slant their observations toward a less-experienced viewer who views under poor skies. There's value in that, but one should not take such "observations" as gospel.
The key? Have a look. Decide what you can see. Look long and hard. Use averted vision. Use multiple magnifications. Push the limits of your scope. Describe what you see in a log.
Ask these questions:
Actual Catalog Size______________________
Magnitude (Total Integrated)_______________
Surf.Brightness_______________
Apparent Sz (visual impression): V.Large / Large / Medium / Small / V.Small/ Stellar / Other_______________________
Apparent Overall Brightness: Bright / EZ / Moderate / Faint / Very Faint / At Limit
Apparent Shape: Round / Round-Oval / Oval / Elong. / Very Elong. / Lenticular / Other______________________________

Nature/shape of core and nucleus____________________________
Superimposed stars_______________________________________
Edge definition___________________________________________
Brightness Gradient_______________________________________
Core % of visible galaxy___________________________________

Don't be surprised if you have something to write in on every line.

#27 uwe_glahn

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Posted 15 August 2007 - 05:07 AM

Hi Oyterdamm,

I tried Stephan's Quintet with 8" and saw 4 separated galaxies. (7317,7318A/B,7319,7320). I find the group quite difficult.
Matthias Juchert tried the group with 8" and saw also 4 galaxies, here is the sketch (scroll to ARP 319)
Martin Schoenball tried it with 10" and saw 5 galaxies, here is the sketch

Exactly like it Steve wrote the challenge is NGC 7320C. With 16", the galaxy can hold with averted vision, see my sketch

Structure within the galaxies could detect with perhaps 20"+. I friend of mine told me about spiral structure of the NGC 7318 pair and NGC 7319 he could detect with 24".

As far as I know NGC 7320 does not belong to the group and represents a foreground galaxy. However NGC 7320C belongs to the group so the "Quintet" is again complete :)

#28 Tele

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Posted 21 August 2007 - 03:17 AM

I give them a look each year at OkieTex. 4 are visible in 8"f5 (the close pair is unresolvable) each year. All are easy in the 14" f4.6. No detail see just orientation and possible the central core popping out once in awhile on one of the brighter ones.

#29 FJA

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Posted 21 August 2007 - 05:38 AM

I have seen Stephan's Quintet in a 12" and 14" SCTs but I've not had a go at them in smaller apertures.

#30 Kaizu

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Posted 21 August 2007 - 09:30 AM

Sunday night, using my frends self made 10" dob, I saw all five. Not any structure but just that they were galaxies, not stars.
The NGC7331 is a god navigation mark for smaller tubes. After that, move a little and imagine that you see something.

Kaizu

#31 Illinois

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Posted 21 August 2007 - 09:55 PM

Starman1 is right! Have a look!
Your eyes stay in dark much longer to able to see a faint tiny fuzzy blob!
I saw NGC 7335 as a tiny fuzzy star when I keep looking for at least 30 minutes! You have to know excatly location then you get chance to see it! Dark sky is very helpful! Don't look at the object......look at little right or left then you might able to see it!
Hood cover your head might be helpful that no light bother your eye!

#32 darklighteditor

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Posted 22 August 2007 - 08:33 PM

This one's my goal tonight...I've (finally) gotten a break in the clouds (luckily, a nice big sucker hole).

Lately, I've spent some time at Sagittaris and recently made a quick trip to Pegasus to try and view the Quint before heading in. I think I was at NGC 7331 and then scanned the area... Was I close?? Should I have just nudged the scope over a bit more?

I know I won't see a lot of the Quint in my 8-inch Dob...but I should see the grouping...right?? (Luckily, I live in a dark sky site.)

#33 mbares

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Posted 03 September 2007 - 05:18 PM

I observed the Quintet last week with my 10" from semi-dark site (NELM 6.2). I was actually surprised how easily one can find SQ by starhopping from NGC 7331. I was able to steadily hold NGC 7320 and unresolved NGC 7318 pair with averted vision. Careful study at higher magnification allowed me to split the pair, but the other two galaxies popped out from time to time beeing too faint for me to see them constantly. After two hours of looking I was pretty sure about the position, shape and orientation of all 5 members. No trace of NGC 7320C though.

#34 zizzapnia

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Posted 05 September 2007 - 09:07 PM

I was able to spot the quintet and differentiate all members- except the two close ones which blended together. A couple of times I could very briefly hold them all at once. Had to spend over an hour on it and it was somewhat grueling, if that term can be applied to astronomy- I'm sure some of you know what I mean. This was in a pretty dark sky on an absolutely crystal clear night with the quintet near the zenith (though the seeing was average). I remember viewing them again later from Cherry Springs, PA, which was darker. The kicker- this was in my *Tasco* 4.5 inch reflector. 10 years ago my eyes were a lot better! I never "dis" cheap scopes anymore.

#35 nytecam

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Posted 06 September 2007 - 05:02 AM

Here's a wideangle finder shot from last night via 135mm fl lens - brightest stars ~mag 9 :rainbow:

Attached Thumbnails

  • 1823459-7331_070905zzz.jpg


#36 Illinois

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Posted 06 September 2007 - 07:49 AM

Hey, nytecam......TWO THUMB UP! That's great!
I use 3 bright triangle stars by NGC 7331 that guide me to know which way to Stephan's Quintet!

Other way is good test is NGC 6207 that's near M13! If you able to see it then you should able to see NGC 7320!

NGC 6207.......12.3 mag size 2' X 1'
NGC 7320 ......12.6 mag size 1.9' X 1'

NGC 7320 is only about .3 fainter than NGC 6207!
Don't worry about other galaxies, just try to find NGC 7320 then work on little higher power to look at other galaxies!
Around 100 power should be good start to spot NGC 7320. I can see it higher than 70 power!

#37 nytecam

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Posted 06 September 2007 - 12:59 PM

Thanks John - you must be in a dark place to view these objects :lol: When I took this pic last night with my piggybacked DSLR+135mm fl lens, mag 3-3.5 stars just visible to the naked-eye - typical for hereabouts - hence the universal use of CCDs for 5 mags [100 times] fainter than any of my scopes visually :smirk:


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