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8" sky watcher dobsonian

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Jimmyboy

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Hi, I have just bought a 8" skywatcher dobsonian, does anyone know of what I am likely to see with it. I have already seen jupitor and its moons, wasnt great but I could see one band around it.

I know the scope is more for deep sky observation, so I have been trying to see galaxies but it is is a nightmare with a fairly light polluted area, trying to find star constellations. The plough AKA big dipper is easily seen and I know the M109 galaxy is near one of the lower stars, but I have no luck in finding it. Andromeda is impoissble to find!! Can anyone give ideas on what im likely to see and what eyepieces to use if possible. If I am able to see a galaxy or nebulea will I be able to see detail in clear no light pollution skies?? or just a blob with a disk or fussy light for a nebulea.

I might upgrade the the scope to a 10" if 8 is not enough. I am fine with collimating the scope

Thanks for any help....
 
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adrenalynn

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I'm constantly chastised for showing "fuzzy balls" to friends.

There are some really rewarding targets out there. You didn't mention where you're from, but assuming the northern hemisphere, there's still time to point your scope at Orion, at the Great Nebula. In dark skies you should even make out color. Under good skies, I can make out the general shape with the naked eye, and it's stunning in good binoculars. And 8" scope visually reaches deep into Orion.

That would be where I'd set you to start.

Remember that the scope is just amplifying the available light. If the light pollution is really bad, big city bad, you're going to see a big fat nothing, since you're magnifying the light pollution as well as the desired light. Going up in scope size will actually hurt what you can see in that environment.

An 8" scope should show you more than one band on Jupiter, but planetary viewing is very effected not only by the light pollution, but also by the stability and clarity of the atmosphere.

You may want to look at passband filters, like city light blockers, assuming you already have some good quality eyepieces. They'll cut some desirable signal, but they'll do a great job of helping to filter the gunk too.

Welcome to the obsession - errr - hobby! ;)
 
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Jimmyboy

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Thanks Adrenalynn, really appreciate that post!!

Unfortuantly im in london so light pollution is quite bad, I did have a look for orion and i usualy see it but i couldnt sunday night for some reason, could only make out the big dipper and I think the pegasus ( trying to find adromeda).

I have only the eye pieces supplied with the scope, i did buy a 6mm.

Was funny I was looking at jupitor through the 10mm and was trying to show my mum it, she kept saying she cant see it, so i focus it again, still nothing... turned out you can see jupitor moving quite fast too!!!

What eye piece do you recomend for galaxy and nebulea watching??

Thanks...
 
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adrenalynn

Guest
Yes, under planetary magnifications, they'll zoom right out of your field of view quickly.

6mm is a lot of magnification.

Mated to inexpensive scopes like that, I've been _very_ happy with the Orion Sirius eyepieces (assuming one doesn't want to spend as much on a single eyepiece as they spent on their scope. Otherwise, it's Televue all the way!)

http://www.telescope.com/control/access ... -eyepieces

For DSO (Deep Sky Objects, which is what you're referring to), 20-35mm. Low magnification with wide field. I don't use anything higher than probably 17mm for DSO. The 25mm Sirius can be quite breath-taking under good skies, with good edge-to-edge light, and fields wider than I can see without moving my eyeball around.

You do need to get out to dark skies before you should expect to see much though! London doesn't favor stargazing, I'm afraid! :(

You might not have been able to locate Orion because it wasn't up yet. It's a winter constellation and only now getting to really show itself early enough to good in some good observation.
 
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crazyeddie

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Jimmyboy":2fdqh53e said:
Hi, I have just bought a 8" skywatcher dobsonian, does anyone know of what I am likely to see with it. I have already seen jupitor and its moons, wasnt great but I could see one band around it.

I know the scope is more for deep sky observation, so I have been trying to see galaxies but it is is a nightmare with a fairly light polluted area, trying to find star constellations. The plough AKA big dipper is easily seen and I know the M109 galaxy is near one of the lower stars, but I have no luck in finding it. Andromeda is impoissble to find!! Can anyone give ideas on what im likely to see and what eyepieces to use if possible. If I am able to see a galaxy or nebulea will I be able to see detail in clear no light pollution skies?? or just a blob with a disk or fussy light for a nebulea.

I might upgrade the the scope to a 10" if 8 is not enough. I am fine with collimating the scope

Thanks for any help....
If you live in London, buying a bigger scope is not going to help all that much, but it WILL guarantee that you will use the scope less often, because a 10" scope is much heavier and bulkier. What you need is the GOTO version and a good light pollution filter. Without a filter, you're limited to planetary viewing and star clusters and only the brightest nebula....but even these objects will be hard to find without a computer to guide you to them.

Galaxies are difficult objects to observe even under dark skies, so keep your expectations realistic. Remember, NOTHING will look the way they do in photographs. They are called "faint fuzzies" for a very good reason.
 
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orionrider

Guest
To find the different objects, install Stellarium on your computer and use it to practice. http://www.stellarium.org/

M31 (Andromeda galaxy) is one of the easiest to find, not far from Cassiopeia, arguably the easiest constellation in the sky (a huge 'W' in the sky). However, be warned that at first you will only see a faint glow, no more. Targets like the double cluster in Perseus (also easy to find, not far from Cassiopeia) give a better view.

Want to know how bad London is for light pollution? Check this: http://avex.org.free.fr/cartes-pl/france/visuel/pl/
London is partly on the map, but you get the picture ;)

A UHC filter will definitely help, but don't expect wonders, and it is expensive:
http://www.teleskop-express.de/shop/pro ... nomik.html
http://www.teleskop-express.de/shop/pro ... nomik.html
Depending on the size of your eyepieces, you need 1,25" or 2". They fit underneath the eyepiece.

Planets and the Moon don't mind the light pollution. However, cities create very turbulent air pockets so that the 'seeing' on the planets can be very bad. On the Moon it looks like there is water flowing on it.
I have the 5" SkyWatcher and on a decent night I clearly see several bands on Jupiter, plus the red spot when it is visible. Your 8" should be much better, but you will have to move to darker skies, somewhere far from buildings and preferably on grass, to avoid turbulence. And let the scope reach ambient temperature, which takes about one hour. Before that, the tube itself is full of turbulent air...

There must be thousands of astronomy clubs in London, be sure to visit one BEFORE you buy anything fancy. People there will show you how to use the 8" Dob properly. You will see it's a very fine instrument to begin with.

Clear skies to you! :)
 
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Jimmyboy

Guest
Thanks for the replies guys, think i will go get a filter, dont feel like driving 30 miles to get a decent veiw in the freezing cold just yet!!!
 
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SpaceTas

Guest
The other type of object that survives light pollution well are star clusters, the best being the globulars. You'll need a finder chart/atlas to find them, a decent finder and a bit of patience/luck. Point the finder to where the object should be and then with a low power eyepiece sweep around a bit. With a good map you could star-hop from a bright star.
The globular clusters, are best viewed at higher magnifications. M13 in Hercules is a northern hemisphere classic example.

Join up with the British Astronomical Society or the Royal Astronomical Society (more scientific). Even if the weather is bad they have good lectures etc on. Greenwhich Observatory has open nights 1 or 2 times a year.

I haven't tried them but there are light pollution filters available that increase the contrast between faint nebula and the sky background.
 
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