Sky bortale rating

[Supernova74]

Hi guys the topic of discussion of the day for me is the sky bortale rating scale and woundering how much differences it does make between the scales I understand some on Astro lounge live in better sky conditions than others and it would be nice to compare sky conditions in a little more detail.the reason why I ask is I’m currently thinking of relocating hopefully in the very near furture as I have no commitments in my neck of the woods which is stoneleigh just outside Epsom downs race course and this maybe a strange question to answer firstly I’ve definitely noticed on some nights. My sky’s seem to be clearer slighty less light pollution and carbon monoxide pollution also as people not useing there cars as much so is it possible that my sky conditions are closer to an 5 then a 6 which it truly is as kind of makes sense really.Anyway I’ve been doing a little research on locations and Sussex ie midhurst and Haselmare way seem not to bad and the bortale rating there is a 4 a little better sky’s i guess as classed as a suburban/rural sky conditions any input much appreciated 

 

[carastro]

Bortle 4 definitely preferable to 5 & 6.  My Home location is Bortle 8 and it sucks (and I am stuck here at the moment during the lock down), but normally travel to East Sussex Bortle 4 for astro imaging, I can do so much mroe there than at home.

Carole 

[ApophisAstros]

The last time i checked with my SQL meter it was 20.44 Bortle 4, yes i can definitely see more stars with the eyes even before my eyes have adjusted.

Seeing when imaging / Guiding is crystal clear.

Worthing , Southern English coast.

Roger

[DaveS]

Last I moved from Ruislip, Bortle 8 with estimated SQI 18.25 to West Dorset, Bortle 4-3 with estimated SQI 21.66. Very much worth it. The Milky Way is visible pretty much as soon as I go out into the garden.

[CCD-Freak]

Confessions of a "Dark Sky Junkie"........Once you experience a clear night under a Bortle 1 or 2 sky you will be ruined for life.

The Okie-Tex star party is held at a site about 40 miles from any town and the sky is Bortle 1.  We have seen the Gegenschein easily and the Milky Way casts your shadow.

http://www.okie-tex.com/index.php

 

John Love
CCD-Freak
WD5IKX

 

My buddy Phil with his C14 at Okie-Tex and a visitor checkin out my batteries.

Edited May 26, 2020 by CCD-Freak

[Jkulin]

I used to live in Stoneleigh, Worcester Park and Ewell, so I do sympathise with you about your skies.

When you visit a true dark sky it will blow your mind, so take your time to find the right place, if I could and didn’t have family, then I would move to a Bortle 3/4.

Good luck.

[ScouseSpaceCadet]

Supernova there's a massive difference. Bortle 4 is the astro playground. Bortle 8 is watching your mates through the playgound railings. A single tear rolling down one's cheek to the sound of a lone distant violin.

Bortle 8 is playing with a slightly deflated football on a cobbled back yard. Bortle 4 is playing on the school football pitch in new football boots. Bortle 2 is scoring at Anfield Stadium in front of the Kop.

 

[DAVE AMENDALL]

I would like to know my Bortle reading from the back garden. but am not prepared to fork out £150 for a meter. The light pollution maps don't see to show enough detail. The mobile app seems to be inacurate showing my semi rural area as bortle 8. So have gave up on this one....Dave

[CCD-Freak]

3 hours ago, DAVE AMENDALL said:

I would like to know my Bortle reading from the back garden. but am not prepared to fork out £150 for a meter. The light pollution maps don't see to show enough detail. The mobile app seems to be inacurate showing my semi rural area as bortle 8. So have gave up on this one....Dave

Try this LP map.   It has some annoying adds but you can zoom in to your location. 

https://www.lightpollutionmap.info/#zoom=4.048366899006263&lat=6999944&lon=-64704&layers=0BFFFFFTFFFFFFFFF

 

John
CCD-Freak
WD5IKX

[DAVE AMENDALL]

Hi John, Thanks for the info.seems I am Bortle 5 at my location. 2 miles away it's Bortle3. I would never have found your map without your help........Dave

[CCD-Freak]

Hi Dave

Glad it was of use to you.  Did you try out all the different overlays and features.

I refer to this map quite often as I look for new dark sites to visit.  I am lucky to have Ft Griffin State Historic Site ( Bortle 2 ) and Copper Breaks State Park about 3.5 house from home.

John
CCD-Freak
WD5IKX

Edited May 29, 2020 by CCD-Freak

[DAVE AMENDALL]

Hi John , I am practicing with the map overlays. fascinating stuff. You have a great  observing location.......Dave

[Waddensky]

5 minutes ago, DAVE AMENDALL said:

Hi John , I am practicing with the map overlays. fascinating stuff. You have a great  observing location.......Dave

Keep in mind that the data from this map is already 5 years old and that the ATLAS layer is the only layer that shows the actual effect of light pollution on the sky brightness. The VIIRS layers are more recent, but they only show the light emitted from light sources as seen from space, not the sky brightness.

You can get reasonably good results estimating your light pollution levels by finding out the dimmest stars you can see from your location (NELM). This of course very dependent on the observer, visual aquity, dark adaptation, etc, so it's kind of a 'personal' bortle classification.

[DaveS]

My eyes are are a bit wonky with age, so the faintest stars I can see are brighter than they should be from how well I see slightly extended objects, and especially the Milky Way.

[DaveS]

On 28/05/2020 at 04:05, ScouseSpaceCadet said:

Supernova there's a massive difference. Bortle 4 is the astro playground. Bortle 8 is watching your mates through the playgound railings. A single tear rolling down one's cheek to the sound of a lone distant violin.

Bortle 8 is playing with a slightly deflated football on a cobbled back yard. Bortle 4 is playing on the school football pitch in new football boots. Bortle 2 is scoring at Anfield Stadium in front of the Kop.

 

And extending your analogy, Bortle 1 is walking up the steps at Wembley to lift the FA cup.

[CCD-Freak]

This was the LP map I was looking for when I posted the other and like mentioned above the data is 5 years old (2015) and I have not seen any 2020 maps as yet.   With LP growing like it is maps are out of date before the ink dries.

I need to edit this with more labels but Fort Griffin is in the center.  I am fortunate to have good skies within a few hours drive.  My home is located under Bortle 5.5 skies and to the south is the Dallas / Ft Worth "metro mess" with it's Bortle 10+ skies.  

 

John Love
CCD-Freak
WD5IKX

Edited May 31, 2020 by CCD-Freak

[Tenor Viol]

On 29/05/2020 at 15:17, CCD-Freak said:

Try this LP map.   It has some annoying adds but you can zoom in to your location. 

https://www.lightpollutionmap.info/#zoom=4.048366899006263&lat=6999944&lon=-64704&layers=0BFFFFFTFFFFFFFFF

 

John
CCD-Freak
WD5IKX

That was useful! Seems that here I'm a Bortle class 4 - and some local street lights go off about 11.30pm so it will be better after that.