Marmot Posted May 22, 2021 Share Posted May 22, 2021 I have come across numerous references to the term ‘Bortle’ which I understand is to do with how dark the sky is (lower number is dark, high number is light). But how do I find out or calculate how the Bortle number is where I live? I have tried the net but I can’t find anything specific to where I live so maybe someone has an appropriate link. I live in Cumbria just west of Penrith and just above the Lake District. There are numerous Listed Dark Sky locations in the Lake District and north of me, so I am trying to decide weather it’s worth driving to them for an observing session one evening or weather the sky where I live is pretty good anyway. thanks for any help. Quote Link to comment Share on other sites More sharing options...
AstronomyUkraine Posted May 22, 2021 Share Posted May 22, 2021 3 hours ago, Marmot said: I have come across numerous references to the term ‘Bortle’ which I understand is to do with how dark the sky is (lower number is dark, high number is light). But how do I find out or calculate how the Bortle number is where I live? I have tried the net but I can’t find anything specific to where I live so maybe someone has an appropriate link. I live in Cumbria just west of Penrith and just above the Lake District. There are numerous Listed Dark Sky locations in the Lake District and north of me, so I am trying to decide weather it’s worth driving to them for an observing session one evening or weather the sky where I live is pretty good anyway. thanks for any help. The easiest way to find your Bortle class is go to the clear outside website, and enter your location. You can also enter any location, and it will give you the Bortle class for that location https://clearoutside.com/forecast/50.7/-3.52 1 Quote Link to comment Share on other sites More sharing options...
Marmot Posted May 22, 2021 Author Share Posted May 22, 2021 (edited) Thanks for the above link. Apparently I am Class 4 Bortle. Hopefully that’s not too bad! Some of the neighbouring villages are Bortle 3. Edited May 22, 2021 by Marmot Adding information. Quote Link to comment Share on other sites More sharing options...
AstronomyUkraine Posted May 22, 2021 Share Posted May 22, 2021 4 hours ago, Marmot said: Thanks for the above link. Apparently I am Class 4 Bortle. Hopefully that’s not too bad! Some of the neighbouring villages are Bortle 3. Same as my location, but looking North I'm probably Bortle 3. Quote Link to comment Share on other sites More sharing options...
Jkulin Posted May 25, 2021 Share Posted May 25, 2021 Sadly since the installation of new LED lights my location has now changed from Bortle 5 to Bortle 6 and the SQM from 19.51 to 19.38🥵😡🤬 2 Quote Link to comment Share on other sites More sharing options...
Marmot Posted May 25, 2021 Author Share Posted May 25, 2021 5 minutes ago, Jkulin said: Sadly since the installation of new LED lights my location has now changed from Bortle 5 to Bortle 6 and the SQM from 19.51 to 19.38🥵😡🤬 I thought the new LED street lights were meant to have a form of cowling to ensure the light was directed downwards to minimise light pollution? i have a street light opposite my house, but fortunately it is so old that it doesn’t always come on🙂 1 Quote Link to comment Share on other sites More sharing options...
gabs Posted May 25, 2021 Share Posted May 25, 2021 2 hours ago, Marmot said: I thought the new LED street lights were meant to have a form of cowling to ensure the light was directed downwards to minimise light pollution? i have a street light opposite my house, but fortunately it is so old that it doesn’t always come on🙂 Light pollution is disaster at least it is where I live. Is good to see that finally some MP are trying to chance the law and improve and preserve the quality of our sky. https://www.google.co.uk/amp/s/www.dailymail.co.uk/sciencetech/article-9034445/amp/Light-pollution-controlled-sake-future-generations-MPs-claim.html 2 Quote Link to comment Share on other sites More sharing options...
gabs Posted May 25, 2021 Share Posted May 25, 2021 2 hours ago, Jkulin said: Sadly since the installation of new LED lights my location has now changed from Bortle 5 to Bortle 6 and the SQM from 19.51 to 19.38🥵😡🤬 Did you try with a slingshot? 😀 I was a good to use it when I was younger! If you need any help let me know 😀 1 Quote Link to comment Share on other sites More sharing options...
Jkulin Posted May 26, 2021 Share Posted May 26, 2021 10 hours ago, gabs said: Did you try with a slingshot? 😀 I was a good to use it when I was younger! If you need any help let me know 😀 Believe me I have thought about it, but I might have to be a crack shot at 1/4 mile away! 1 Quote Link to comment Share on other sites More sharing options...
DaveS Posted May 29, 2021 Share Posted May 29, 2021 According to CO I have SQI 21.66 and the dark end of Bortle 4, nearly 3. The nearest streetlights are 4-5 miles away so would need field artillery to put them out. 1 Quote Link to comment Share on other sites More sharing options...
MarkAR Posted June 18, 2021 Share Posted June 18, 2021 On 5/29/2021 at 8:38 PM, DaveS said: According to CO I have SQI 21.66 and the dark end of Bortle 4, nearly 3. The nearest streetlights are 4-5 miles away so would need field artillery to put them out. Yeah, I'm not jealous at all. 🤣 Light Pollution Map https://www.lightpollutionmap.info/#zoom=7.41&lat=51.5929&lon=-0.5453&layers=B0FFFFFTFFFFFFFFFFF 1 Quote Link to comment Share on other sites More sharing options...
jcj380 Posted June 20, 2021 Share Posted June 20, 2021 I consider B4 to be a dark site. I live in a 7-8. 😧 1 Quote Link to comment Share on other sites More sharing options...
Marmot Posted June 21, 2021 Author Share Posted June 21, 2021 On 6/18/2021 at 6:42 PM, MarkAR said: Yeah, I'm not jealous at all. 🤣 Light Pollution Map https://www.lightpollutionmap.info/#zoom=7.41&lat=51.5929&lon=-0.5453&layers=B0FFFFFTFFFFFFFFFFF That’s a really useful link. Thanks for putting the link on here. I grew up in Surrey (close to Guildford) so it was interesting to see how it compares to where I am now. 1 Quote Link to comment Share on other sites More sharing options...
Galileo Posted May 31, 2022 Share Posted May 31, 2022 (edited) I think the way light pollution is going we'll need to we'll need to increase the scale to 11, bit like the amplifier on Spinal Tap! Edited May 31, 2022 by Galileo 2 Quote Link to comment Share on other sites More sharing options...
Kevin17 Posted October 7, 2022 Share Posted October 7, 2022 From what i can make out from the Light Pollution Map app my village / house is in a level 4 area in rural Lincolnshire, although if i drive 10 minutes i can get into the middle of fields with only a few houses around for and no big towns for about 5 miles, its still classed as level 4 but i would say it seems noticeably darker than at home in my garden. Should be a screen shot below. Quote Link to comment Share on other sites More sharing options...
Galileo Posted October 7, 2022 Share Posted October 7, 2022 (edited) I have thought about splashing out on a sky quality meter but they are a bit pricey for just knowing pretty much what CO is telling you and I might become too obsessed with taking readings and do no AP 😕 , The way I look at it is you're stuck with whatcha got unless you travel to darker skies and the situation ain't getting any better! I travel from Telford (B5) to various imaging sites to the West depending on weather, whether I can be bothered to cart my gear to the top of Clee Hill, whether I'm staying all night. The best is a B2/3 so as good as it gets without going to Scotland. On a recent camping trip to Bude in Cornwall I saw the best milky way ever and I estimate that was B2/3. It went right down to the horizon, stunning. Edited October 7, 2022 by Galileo Quote Link to comment Share on other sites More sharing options...
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