How to determine the magnitude of your area/city

[Canter_Zac13]

I remember seeing a website that had a chart that compared the stars that you can see in the bowl of the big dipper to the magnitude. I can't find it but I want to know how so I can calculate the magnitude in my area. Does anyone know of a website or know what I'm talking about?

 

[John]

Here is some info on working out Naked Eye Limiting Magnitude (NELM) using stars in Ursa Minor:

https://darkskydiary.wordpress.com/2012/01/20/naked-eye-limiting-magnitude-assessing-sky-brightness/

Here is another link which gives you a much wider choice of constellations and stars to use:

http://obs.nineplanets.org/lm/rjm.html

Edited January 4, 2017 by John

[Canter_Zac13]

Thanks!

[popeye85]

Remember though that the first link that John posted up refers to Ursa MINOR. Not the big dipper.

[John]

16 minutes ago, popeye85 said:

Remember though that the first link that John posted up refers to Ursa MINOR. Not the big dipper.

Indeed. Thats the constellation that I most regularly use to estimate my NELM.

[popeye85]

 Of course number of visible stars seen from a location also depends on how good your eye sight is! One person might count X number of stars but someone stood right next to them may count more or less stars.

[Mr Spock]

Here's a map of Ursa Minor with magnitudes which may help.

[ADSmith]

Isolating your self from nearby lights and becoming fully dark adapted goes a long way too. I've seen the faintest outlines of the Andromeda galaxy and the Orion Nebula in my 70mm apreture 500mm focal length refractor and I'm just outside of a pretty metro area but according to clearoutside.com I'm in a class 5 Bottle area.

[John]

25 minutes ago, ADSmith said:

Isolating your self from nearby lights and becoming fully dark adapted goes a long way too. I've seen the faintest outlines of the Andromeda galaxy and the Orion Nebula in my 70mm apreture 500mm focal length refractor and I'm just outside of a pretty metro area but according to clearoutside.com I'm in a class 5 Bottle area.

My skies are Bortle 5 according to "Clear Outside". I can see quite a swathe of the milky way, the Andromeda Galaxy and the Orion Nebula without a scope, on a decent night.

Another interesting test of local darkness in the winter is the Orion star count:

https://www.cpre.org.uk/what-we-care-about/nature-and-landscapes/dark-skies/star-count-2021/