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What Galaxies would show structure?

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#1 judebox

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Posted 11 September 2019 - 01:34 PM

Hi, I own an 8 inch skywatcher dobsonian and have been using with great success. 

I was just wondering if there were any galaxies that would show a little bit of spiral arm structure or maybe dust lane. Andromeda didn't show a dust lane last night but ill keep observing it every clear night. 

I live in Ireland and in bortle 3 skies but generally poor seeing and transparency according to Astropanel app.

Thanks



#2 GoFish

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Posted 11 September 2019 - 01:44 PM

I can catch a hint of M31 dust lanes in my 10” Dob from my badly light polluted driveway in Bortle 6/7 zone. I would expect you’d be able to see them in your 8” from Bortle 3. Bad seeing would not be an impediment to viewing the dust lanes, although low transparency would be. 

 

Andromeda is surprisingly large. Perhaps you just need a wider angle view?



#3 fcathell

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Posted 11 September 2019 - 01:53 PM

If you can get to some really dark skies you may be able to see some structure in M51, and M31 should be very easy to see the dust lane.  Also, M-104 (Sombrero) will definitely show an edge on dust lane. Another good edge on is NGC4565 with a very noticeable dust lane.  Got to have dark skies, however. The biggest scope in the world is no substitute for dark skies!

 

Frank


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#4 rowdy388

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Posted 11 September 2019 - 01:58 PM

M51 shows me the most spiral arm structure. M33 probably slows the most detailed nebula regions

in my northern latitude Bortle 4 sky. Your Bortle 3 sky sounds nice. My seeing and transparency are

both usually bad same as you.



#5 Sketcher

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Posted 11 September 2019 - 02:58 PM

Hi, I own an 8 inch skywatcher dobsonian and have been using with great success. 

I was just wondering if there were any galaxies that would show a little bit of spiral arm structure or maybe dust lane. Andromeda didn't show a dust lane last night but ill keep observing it every clear night. 

I live in Ireland and in bortle 3 skies but generally poor seeing and transparency according to Astropanel app.

Thanks

The moon is approaching full and was up from before sunset until well after midnight.  Perhaps you were observing M31 this morning, after the moon had set and before the sun rose higher than minus 18 degrees.  Otherwise, you're basically shooting yourself in the foot -- looking for galactic structures under avoidable sky glow.

 

A good way (perhaps even the best way) to find out which galaxies will show structure is to carefully study any of the brighter galaxies when they're 30 degrees or (preferably) higher in your sky, or on your south meridian -- and when the sun is no higher than minus 18 degrees in altitude -- and when the moon is below your horizon.  Then you'll be able to tell the rest of us which galaxies show structure!


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#6 judebox

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Posted 11 September 2019 - 03:00 PM

Thanks for the input, M51 is quite low on the sky right now but i saw it around a month back and it kind of looked like a question mark to me but i think i mightve used a bit of imagination lol. not obvious spiral arms but with averted vision i could the the classic picture shape in a foggy way, i think the transparancy mustve been good on that night.

Alot of you say get to a dark sky spot but I was under the impresion that bortle 3 was considered pretty dark, Is there a big difference between bortle 3 and 1? Ireland is quite small so theres only so far you can get away from towns but a mountainous region with bortle 1 is avaliable to me in kerry, around a 3 or 4 hour drive. 



#7 Migwan

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Posted 11 September 2019 - 03:50 PM

If your dob is f5.9 you should be able to catch dust lanes in M31, if you get a transparent night.    You want low power with something that gives you more than 3.5°.   Darker is always better, but Bortle 3 should do it on a transparent night.   Specially at zenith.

 

M51 is going to be pretty low.  I can usually spot some debris in M82, but like M51 it pretty low and will be more suitable come spring. 

 

Good luck

 

jd



#8 starcanoe

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Posted 11 September 2019 - 03:56 PM

One thing to keep in mind.

 

The word on the street (the one with the mecury vaport, high pressure sodium, and led lights) is that Andromeda is the biggest and best galaxy.....well, yeah it IS the biggest and brightest....but in my experience unless you are in REALLY dark skies and or have a really big scope...well in terms of interesting detail....it kinda sucks in general. Another handful or two of OTHER galaxies...that while not so bright...have a heck of lot more detail in modest but capable of scopes...I leave that list to others that can remember that stuff better off the top of their heads...


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#9 judebox

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Posted 11 September 2019 - 03:56 PM

If your dob is f5.9 you should be able to catch dust lanes in M31, if you get a transparent night.    You want low power with something that gives you more than 3.5°.   Darker is always better, but Bortle 3 should do it on a transparent night.   Specially at zenith.

 

M51 is going to be pretty low.  I can usually spot some debris in M82, but like M51 it pretty low and will be more suitable come spring. 

 

Good luck

 

jd

thanks for the advice, my skywatcher 200p is f/5 i think, im using a celestron zoom lens which give me a 24mm lowest option I think



#10 starcanoe

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Posted 11 September 2019 - 04:16 PM

Another random observation....besides using a REALLY big scope and looking at SMALL details within the Andromeda galaxy..about the only time I've actually looked at the galaxy has been with scope on the smaller side with max exit pupil and really dark / transparent skies and or big binocs under the same conditions.

 

And I've been doing this on and off since 1976 give or take...and seriously as an "adult" ( I use that word loosely mind you :) ) since the mid 80's AND I live in the southern USA AND have had easy access to probably one of the top handful of dark sites in the eastern half of the USA...AND can get downright obsessive about being as dark adapted as one can be.

 

For me....that galaxy has always been like some place to go eat that lots of folks rave about...so once in awhile I go there...and I go "meh" when I am done....rinse lather repeat every year....

 

Don't get me wrong...from a intellectual point of view it is pretty **** amazing...and from a dark site and some decent 7 by 50 binocs or a modest scope working at lowest possible power the view ain't too bad....but for me it never blows my socks off. To me it is kinda like M42...but without any significant detail.



#11 Migwan

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Posted 11 September 2019 - 06:13 PM

thanks for the advice, my skywatcher 200p is f/5 i think, im using a celestron zoom lens which give me a 24mm lowest option I think

You need to go much wider for Andromeda.   Starcanoe is correct in that small fast wide field scopes do better at this.  For me its been an ST80 and ST120 on this target.   With what you said about transparency in your area, it might not be worth pursuing an expensive low power wide field eyepiece just for Andromeda.    With a bit more thought, I not sure you can get wide enough to do any good.   Might better to try M51, M104, M82 or others next spring.      jd



#12 stoest

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Posted 11 September 2019 - 11:26 PM

The dust lane in Andromeda is one of those things I saw many times before I "saw" it.  The way I describe it to people looking through my scopes is to look on the opposite side from M32 and compare the very gradual drop off in brightness on the M32 side to the other side and you'll see that this side has a much more abrupt change in the brightness.  That's the edge of the first dust lane you see in pictures. For me it took a while to realize that everything was much larger than I expected it to be, so I wasn't looking in the right places.  In my 9.25 scope, on a good night I can just see the glow pick back up on the other side of the sudden drop off which is the area between the first and second dust lanes.  In the 18" I can see that second area drop off which is the second dust lane and pick back up on the other side of that dust lane.  I'm not sure you'll be able to pick that up in an 8 unless you have really dark skies.  

 

Sometimes I can see the dust lanes better at moderate magnification but you're only looking at a small slice of the whole galaxy.  

 

It wasn't till I started looking for NGC 206 and finding star patterns to find it that I realized how far M31 extends.  The brightness change is so gradual that it really takes some time to see what's there.  M31 is one of those objects that rewards time spent, it looks featureless at first but there's quite a bit there.


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#13 NorthernlatAK

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Posted 12 September 2019 - 12:25 AM

Ngc 2903 in leo shows a bar and condensations at the end leading to arms. I have a similar scope, skies, and latitude. It definitely showed structure, quite impressive, really.
M51 shows a bit of structure too.
Be patient with m31 on a real transparent night and keep your eyes dark adapted. Bortle 3 is plenty dark to show the glory of m31! Use your lowest power ep. It's still too big to fit the whole thing though...

#14 Tony Flanders

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Posted 12 September 2019 - 05:48 AM

In genuine Bortle 3 skies (meaning that you can see the Milky Way with ease and in detail), through an 8-inch scope, the spiral arms of a half dozen galaxies are pretty obvious -- once you know what to look for. Figuring out what to look for and training my eye to do so took me about two or three years.

 

At this time of year, M33 is your best bet. But it's tricky; the spiral arms are huge but not terribly well defined. Anyway, while engaged in the relatively easy task of observing all the nebulae and star clouds inside M33 that have NGC numbers, think carefully about how they all hook up, and see if you can discern some structure to it.

 

In late winter or spring, M51 is by far the easiest galaxy for a northern novice to spot spiral arms. M51 has much higher surface brightness than M33, and the arms are much narrower and sharper.

 

In all cases, I found that the trick is to look not for the arms themselves, but rather for the dark spaces between the arms.


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#15 Illinois

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Posted 12 September 2019 - 06:29 AM

I can see M101 and M51 arms in my 16 inch in yellow zone. Not easy to see arms or dust line in M31 and NGC 7331.

#16 Araguaia

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Posted 12 September 2019 - 12:51 PM

I think the best way to see the dust lanes in M31 is to center on the core and then let it drift at high magnification.   As the dust lanes cross the center of the field they tend to pop out for most people.


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