How useful is the Bortle scale ?

[wookie1965]

38 minutes ago, faulksy said:

im moving soon to a near bortle 3 area measures with my sqm 21.68 should be ace 😆 this is uk, spain fell through. 8 weeks left untill we move to mid wales

Closer to the Bala site?

[faulksy]

9 minutes ago, wookie1965 said:

Closer to the Bala site?

closer to elan valley

[faulksy]

15 minutes ago, bomberbaz said:

Have you taken tgese readi gs from a lp map, cos they are not most accurate. However if you can get 21.82, that is black, milky way casting a shadow dark!

took the readings myself steve 😆

[Captain Scarlet]

The chart showing the data I posted a bit earlier in the thread shows “darkest nights” regularly a little bit darker than that suggested by the Atlas 2015 layer on lightpollutionmap.info . The Sunbury-on-Thames data show best values of around 19.15 whereas the website suggests 19.05. And my dark location is a suggested 21.80 and only a few weeks ago I recorded 21.97 .

So two locations at opposite ends of the scale agree reasonably well with that website (which incidentally is where Clear Outside gets its data too I think.

Magnus

Edited May 21, 2022 by Captain Scarlet

[faulksy]

1 hour ago, niallk said:

Sorry to hear Spain fell through Mike, and best of luck with the new move.

quite happy nial. a lot easier and happier

[Pixies]

Faulksy's back garden for Star Party 2022?

Do you have electrical hook-up?  

[faulksy]

2 minutes ago, Pixies said:

Faulksy's back garden for Star Party 2022?

Do you have electrical hook-up?  

yes and tent space 🤣

[ScouseSpaceCadet]

6 hours ago, faulksy said:

im moving soon to a near bortle 3 area measures with my sqm 21.68 should be ace 😆 this is uk, spain fell through. 8 weeks left untill we move to mid wales

Lovely. You will only get five clear nights a year, however they will be magnificent! 😆

Enjoy. 👍

[Captain Scarlet]

41 minutes ago, ScouseSpaceCadet said:

Lovely. You will only get five clear nights a year, however they will be magnificent! 😆

Enjoy. 👍

Two of those will be moonlit of course 🙂

[Astro Noodles]

2 minutes ago, Captain Scarlet said:

Two of those will be moonlit of course 🙂

And two during the summer. 🙂

[badhex]

I do totally agree that the Bortle scale is a finger in the air estimate, and take it with a pinch of salt accordingly - but especially for newcomers it is perhaps easier to use than SQM as a rough gauge, provided you're aware that it is indeed rough. 

Edited May 21, 2022 by badhex

[alacant]

Like many measurable quantities in this game, we don't find it at all useful.

Can we see the milky way? Sometimes not. Usually because there's haze, the moon is up, or it's March. Does haze and the moon play a part in the scale? I don't know. 

Cheers

 

Edited May 22, 2022 by alacant

[DavieH]

I have to admit to being really confused by the Bottle scale. I'm close to central Bath and according to Clear Outside that's Bottle 5, which is ok-ish I think? However, because Bath is surrounded by hills air pollution can get pretty bad when we get settled weather so surely that would affect viewing?

[Pixies]

19 minutes ago, DavieH said:

I have to admit to being really confused by the Bottle scale. I'm close to central Bath and according to Clear Outside that's Bottle 5, which is ok-ish I think? However, because Bath is surrounded by hills air pollution can get pretty bad when we get settled weather so surely that would affect viewing?

Yep. The Bortle scale is for the observer to calculate for their local conditions. The estimates from CO and the light-pollution map are calculated from known data, but are just estimates of expected conditions.

The Bottle scale, though, is something completely different!

[DavieH]

I have mixed those two scales up from time to time - definitely got more hazy as the night went on...

[jetstream]

22 hours ago, DavieH said:

I have mixed those two scales up from time to time - definitely got more hazy as the night went on...

Forget the Bortle scale- judge sky darkness by the appearance of the Milky Way, if you cant see it at all forget DSO viewing, with the exception of a few objects like the filtered Ring neb and view instead star clusters etc.IMHO

Edited June 22, 2022 by jetstream

[DavieH]

Thanks Jetstream, that's a useful rule of thumb. Disappointing as I haven't seen the Milky Way from here for ages!

[Ags]

58 minutes ago, jetstream said:

Forget the Bortle scale- judge sky darkness by the appearance of the Milky Way, if you cant see it at all forget DSO viewing, with the exception of a few objects like the filtered Ring neb and view instead star clusters etc.IMHO

I will respectfully reject your counsel of despair. I haven't seen the milky way from my back garden for 12 years, but I still go hunting for DSOs. Maybe my expectations are lower? I'm just happy to find them!

The main drawback with the Bortle Scale is it only officially goes to Nine. It must be at least Eleven round these parts 🤣

[jetstream]

39 minutes ago, Ags said:

I will respectfully reject your counsel of despair.

I wasnt meaning to sound discouraging- just giving a realistic view of the Bortle scale and expectations. Bortle 5 says you can see hints of zodiacal light? By all means seek out DSO at all times, its a great sport.

[jetstream]

1 hour ago, DavieH said:

Thanks Jetstream, that's a useful rule of thumb. Disappointing as I haven't seen the Milky Way from here for ages!

If you can get to dark skies at least once under good conditions and view the Milky Way/DSO then youll see what I mean. In light polluted skies night vision can be very useful.

Now waiting from the NV crowd to tell me how its just not for LP skies.... and they are right.

[Ags]

Dark skies certainly help, and I do treasure my trips to dark skies, but regardless of light pollution levels its fun standing alone outside sharing the quiet darkness with the gently humming mosquitoes, gliding this way and that with a fine telescope. Even if the destination is an averted vision smudge, there is still the fun of chasing it down.

I observe with a small refractor in a city, chasing things at the limit of my vision. Give another astronomer a 24" dob and pitch black skies and what do they end up doing? Hunting down obscure ICs and NGCs at the limit of their vision!

[Zermelo]

1 hour ago, Ags said:

it only officially goes to Nine. It must be at least Eleven round these parts

[faulksy]

1 hour ago, Ags said:

Dark skies certainly help, and I do treasure my trips to dark skies, but regardless of light pollution levels its fun standing alone outside sharing the quiet darkness with the gently humming mosquitoes, gliding this way and that with a fine telescope. Even if the destination is an averted vision smudge, there is still the fun of chasing it down.

I observe with a small refractor in a city, chasing things at the limit of my vision. Give another astronomer a 24" dob and pitch black skies and what do they end up doing? Hunting down obscure ICs and NGCs at the limit of their vision!

that is the scope gerry  @jetstreamhas and mag 21 .8 skys

 

 

 

 

 

 

 

 

 

[McQ]

According to maps I'm Bortle 6 but you can read a newspaper in my front yard at night because of the streetlights. I'm sure the B scale is fine, but the maps can't account for every individual locality. 

[jetstream]

17 hours ago, Ags said:

Give another astronomer a 24" dob and pitch black skies and what do they end up doing?

Oddly enough I enjoy the mind blowing views of brighter objects in my 24" better than threshold objects. A threshold object for the 24" looks the same as a threshold object in any other scope IMHO.

The Veil in the 24" under dark skies is hard to describe, but I'll try- mind blowing!