advice on deep sky limits with my scope

[stafford_stargazer]

Hi

I have a skywatcher 200p dobsonian,just getting a 2 inch 32mm panaview eyepiece next week,i am interested in deep sky stuff,what can i expect to see with that combination?

Is it a good combination for deepsky?

What limiting magnatude i will be able to see down to?

Thanks all your knowledge is priceless.

Gary

[John]

It all depends on your local seeing conditions. With little or no light pollution you will be able to see hundreds of Messier and NGC objects.

If you have to contend with some LP then things will be more challenging.

There are no hard and fast rules I'm afraid. I was amazed at what I could see with quite modest scopes under the dark skies at the SGL4 and 5 star parties - it was like adding 50% more aperture in that my 6" refractor was showing views of DSO's similar to the ones my 10" newtonian gives from my moderately light polluted back garden.

The eyepiece you have bought is good for DSO's with your scope - the best advice I can give is to give it a whirl and see how it goes.

[kniclander]

if you want galaxies, the best place to start is virgo / coma berenices - if your skies are dark enough to glimpse the asterism "berenice's hair" then you will be able to see quite a few galaxies there - just by sweeping around with your scope. If you are star-hopping vindiemiatrix (spelling?) is a good jumping off point - it's a distinctly "orangey" star at the top of the sort of straight line in virgo.

God luck

[Beulah]

There is actually a chart on this site...scroll down to the highlighted part of this page - it gives you a "rough" idea of telescope capabilities...bearing in mind things such as your own eyesight, sky conditions, etc.

Choosing a 35mm camera

[richbyers]

thats a good scope you ve got, was looking at one myself.

youl be able to see alot with that, galaxies, nebulae, clusters, double stars. A good place to start would be ursa major, check out some of the galaxies there, mind you deep sky observing window is pretty closed with the long summer days now

rich

[moocher]

Magnitude limits depend on...

A/ LP

B/ Aperture

Nothing to do with eyepieces its all about how big your mirror or lens is....You`ll obviously see more if your observing at a dark site.

Alan:D

[acey]

As has been said, an 8-inch scope will give great views of hundreds of DSOs. As has also been said, the crucial thing is the darkness of the sky.

A telescope doesn't make DSOs brighter (i.e. has no effect on surface brightness), it makes them bigger. If you can see M31 (the Andromeda galaxy) with the naked eye then you'll get a fantastic view of it with any instrument. If you can't then the most you can hope for is the small bright core (which is too small to distinguish with the naked eye).

If you can't see the Milky Way with the naked eye from your location then you may be able to see the cores of galaxies, but don't expect too much. Be selective in your viewing: go for star clusters and planetary nebulae. With an 8-inch from my severely light-polluted garden (limiting mag 4.5) I've had jaw-dropping views of objects such as the Ring Nebula and Double Cluster. Also the bright inner regions of large galaxies such as M81.

The eyepiece does nothing except fit all the light inside your eye pupil, hopefully with the minimum of distortion. The more you pay, the less distortion you expect (and you generally get a bigger field of view too). The size of the field of view has a big aesthetic impact, makes manual tracking easier, and means that very large objects can potentially fit within the field. In other respects, field of view is irrelevant.

When viewing galaxies, low power gives the brightest view (in theory, equal to the actual surface brightness of the object). Increasing power makes the view dimmer but makes details easier to see. Most beginners are content to see a galaxy as a featureless blob (which is still a big thrill, believe me), so low power is fine in those cases. But if you want to see the spiral arms of M51 (which can be done with an 8") then you'll need a high-power eyepiece, a place where the Milky Way is easily seen with the naked eye, and a little bit of experience.

The theoretical magnitude gain of your scope is 5log(200/p) where p is the diameter of your pupil. If we take p=7mm then we get a gain of about 7 magnitudes, so if you can see stars as faint as magnitude 5 with the naked eye then you'd expect to get down to 12 with the scope. That's theory: in practice it might be more or less. And this is the magnitude of stars that you'll see, not unresolved extended objects (galaxies, nebulae etc), where surface brightness (and hence sky darkness) is what counts. In practice you've really just got to have a try and see how deep you can go.

You've picked a great scope and should have a lot of fun with it.

[Llamanaut]

can only echo the point about dark skies. From light polluted weymouth i can barely see any dso's apart from the brightest even with 12 inches of aperture.... 10 miles outside in the countryside and ive bagged 65 in 2 days, i think dark skies is the the main overiding factor

[Pete Presland]

dark skies essential,but it varies from night to night,or even during the same night!

nice scope though

[Astro_Baby]

I have the 26mm and 38mm Panaview and use them in an 8" Newt thats similar to yours. Where the 38mm really shines is on large diffuse objects such as the Pleiades (M45) the Orion Nebula (M42) and open clusters like the bee hive.

Its wide field of view coupled with its very contrast loaded views will make the best of any large, diffuse or scattered objects. I was using my 38mm a few months back to see Mars cross close to the bee hive and it was a great view.

I havent used the 32mm but my guess would be it would be similar to the 38mm. The 26mm I seldom use except as a finder eyepiece. You should find it a nice view and also a very comfortable one. Thats what I like with the Panaviews they are easy on the eyeballs and well behaved.

Get some eyetime in with the 32mm I am sure it wont disappoint and will probably spoil you a lot and make you want to spend more money on even more exotic glass.

Oh - one tip - make sure when you use it you twist the rubber eyecup up. The amount of times I use mine and forget to wind out the eyecup and then wonder why the EP keeps blacking out is in the dozens and I have seen others do the same thing.