Orpington Astronomical Society

Astronomy => Technical => Topic started by: Fay on Nov 08, 2014, 08:41:18

Title: Dark Sky Magnitudes
Post by: Fay on Nov 08, 2014, 08:41:18
how do you find out dark sky magnitudes for your area?
Title: Re: Dark Sky Magitudes
Post by: Mac on Nov 08, 2014, 11:02:15
Look up, If you can see anything, its dark.  :cheesy:

Use Ursa Minor as your viewing chart, work out what the dimmest star is you can see and take it from there.

(http://astrobob.areavoices.com/files/2010/12/UMi-mags2-1024x780.jpg)

Mac
Title: Re: Dark Sky Magitudes
Post by: mickw on Nov 08, 2014, 11:06:07
Or...................

A simulation is here (and somewhere on this site)
http://www.need-less.org.uk/night%20sky%20simulator.html# (http://www.need-less.org.uk/night%20sky%20simulator.html#)

Title: Re: Dark Sky Magnitudes
Post by: Mike on Nov 08, 2014, 15:05:11
The stars inside the SQUARE OF PEGASUS (http://freestarcharts.com/index.php/stars/17-guides/stars/17-how-dark-are-your-night-skies) also make a good indicator.
Title: Re: Dark Sky Magnitudes
Post by: mickw on Nov 08, 2014, 17:01:31
Or..............................

Get one of these and don't trust your eyes  ;)

http://www.altairastro.com/product.php?productid=16244 (http://www.altairastro.com/product.php?productid=16244)
Title: Re: Dark Sky Magnitudes
Post by: Carole on Nov 09, 2014, 00:43:54
I've always used the Bortle Scale, non technical but simple explanation. 
http://www.skyandtelescope.com/astronomy-resources/light-pollution-and-astronomy-the-bortle-dark-sky-scale/

Carole
Title: Re: Dark Sky Magnitudes
Post by: Fay on Nov 09, 2014, 08:33:26
Thanks for all that. what is it that Mark holds up to the sky to measure it. eg Kielder is 21.9
Title: Re: Dark Sky Magnitudes
Post by: mickw on Nov 09, 2014, 09:13:14
One of these
http://www.altairastro.com/product.php?productid=16244 (http://www.altairastro.com/product.php?productid=16244)
Title: Re: Dark Sky Magnitudes
Post by: Fay on Nov 09, 2014, 09:17:33
thats it Mick
Title: Re: Dark Sky Magnitudes
Post by: JohnP on Nov 09, 2014, 14:08:10
Why do you want to know Fay?
Title: Re: Dark Sky Magnitudes
Post by: Fay on Nov 09, 2014, 15:00:40
someone was asking about my skies.