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performance under poor sky


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CLS filters and other broad-band light pollution reduction filters work best if the LP is narrow band (low-pressure sodium lights, mercury lights) They are less good under broad band lighting (xenon, LED, high-pressure sodium). UHC filters work well for emission nebulae and planetaries, even when the LP itself is broad band. They do not do well on galaxies and reflection nebulae

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Hello. Is there any feature of a reflector telescope that makes it perform better under poor sky conditions (like light pollution)? Aperture, focal length, quality of the eyepieces? Thank you.

I think it's fair to say that all telescopes of all types perform less well under a poor sky and better under a good sky.

I would make your choice by other factors, like what type of astronomy you wish to pursue, portability, whether you prefer low tech or high tech, and of course your budget.

Hope that helps, and all the best in your decision, Ed.

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Two things to say here...

LP is basically LP and difficult to get good results on fainter objects with regardless of the scope.

Choose objects with higher surface brightness and you will have more luck so, very roughly in order, the moon, planets, double stars, globular clusters, planetary nebule and open clusters

Planetary nebulae and emission nebulae respond well to either UHC or OIII filters

For galaxies and more faint objects, best option is to get in the car and go somewhere dark! A small scope under dark skies can be pretty impressive.

Stu

EDIT: that was a few more than 2 things....

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Portability if your sky is badly light polluted. 

The simple fact remains portability is your friend if you are living with poor sky conditions. Nothing will make as much difference to your observing pleasure than getting out from under LP skies.

Filters can help with certain objects (Nebulae) as Michael has mentioned above, but be aware they are no substitute for dark skies and in fact work best from skies that are already dark.

For observing deep sky objects a tank of gas is the best accessory one can buy.

On a brighter note, the moon and planets are not effected by light pollution and can be observed from any location with equal success. 

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If you do suffer from horrible light pollution, it's more pleasing to use a refractor than struggle. A small refractor 102-120 will give you stunning views of double stars , star clusters and planetary nebulae from the edge of town.

It'll give results in Moon light as well as high cloud. Worth a try ,

Nick.

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I personally do not see why a refractor does better than a larger reflector (my old 6" F/8 Newtonian could take most 4 and 5" achromats to the cleaners on both planets and double stars.)

I can't see why either Michael but my ED120 refractor often does deliver far closer to the performance of my 12" dob than it has any right to on the Moon and planets and, while it's ultimate resolution is lower, the way it presents binary stars is much cleaner and preferrable to my eye. My 12" dob is a good one too with 1/9th wave PV primary and a strehl rating of .987

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I've been skygazing a bit tonight from the terrace of my house (10,30 pm). On naked eyes I could spot stars with 2.50 magnitud and brighter, of course. I grabbed my binoculars (7×50) and I could spot stars with about 5 magnitud. How good or bad is my sky?

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Mag 2.5 sounds pretty bad unfortunately :-(, is that really as low as you can go?

My skies are around mag 4.5 most of the time, but can get down to 5 in good conditions. I think mine are bad enough!!

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Mag 2.5 sounds pretty bad unfortunately :-(, is that really as low as you can go?

My skies are around mag 4.5 most of the time, but can get down to 5 in good conditions. I think mine are bad enough!!

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I gazed again an hour later and maybe it's not so bad. I spotted some stars around Cassiopea that are 3.54. I also spotted some objects under the belt of Orion that could be 4.5 but that area is a bit crowded with other objects and I'm not sure. Anyway, today I'll receive my new telescope and, if clouds allow me, I'll find out how bad it is. About 10 pm I've got Cassiopea just in front my house. That will be my first target. Thanks.

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One way to assess how dark your skies are is to see how many stars you can see within the Great Square of Pegasus. Here is some information on that:

http://freestarcharts.com/index.php/stars/17-guides/stars/17-how-dark-are-your-night-skies

Another way is to see how many stars you can see of the square or bowl shape of Ursa Minor. The 4 stars that make up that formation have magnitudes of approx 2, 3, 4 and 5 respectively so can be a useful guide.

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looking with unaided eye today at  Cassiopea after 5 mins in dark at around 10 with half moon i can resolve the 4 stars in its right wing they around 6mag

wing with Cih , Caph , Shedar 

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