Bortle?

[Sunshine]

In my early years as an amateur the word "bottle" didn't come across my radar, this is back in the mid 90's. When describing the quality of skies we used magnitude, I recall reading an article in an astro magazine describing

the beautiful sixth magnitude skies of Arizona. Forward a decade as I dropped out of astronomy when I got married and had to get a real job and a home, suddenly I encountered the word bortle!. Right away I knew I hated it, I can barely 

say it, it sounds awful, not sure how one can hate a word but I do.

 

When did "bortle" happen?

Edited December 16, 2021 by Sunshine

[JeremyS]

Wiki says John Bortle published the article describing it in Feb 2001 S&T

[JeremyS]

Article: https://skyandtelescope.org/astronomy-resources/light-pollution-and-astronomy-the-bortle-dark-sky-scale/

[Sunshine]

5 minutes ago, JeremyS said:

Article: https://skyandtelescope.org/astronomy-resources/light-pollution-and-astronomy-the-bortle-dark-sky-scale/

Interesting! Thank you, Jeremy, but I still hate the word bortle 😂

[JeremyS]

I’m also of the era that thinks in terms of the limiting magnitude of a sky, rather than its Bortle rating

[niallk]

I don't hate Bortle - just frickin 'security' lights 😂

[johninderby]

A bit of useless info on the Bortles 🤔😁

The ancestors of the bearers of the Bortle family name are thought have lived in ancient  Anglo-Saxon  England. They were first found in either the settlement of Birtle in the county of  Lancashire or the settlement of Birtles in the county of  Cheshire. The names of these places are derived from the Old English word bridd, meaning young bird or nestling, and indicates that the places were originally known as nesting grounds for birds.

[Stu]

11 hours ago, JeremyS said:

I’m also of the era that thinks in terms of the limiting magnitude of a sky, rather than its Bortle rating

Me too really. I use Bortle somewhat begrudgingly, often because newer starters to the hobby use it more frequently and find it useful.

To me it’s a fairly flawed system and the descriptions don’t necessarily match my experiences.

[vlaiv]

Any description of sky brightness is bound to be flawed in terms of matching experience - since experience depends on other factors as well.

Transparency plays vital role in what can be seen - regardless of sky brightness. In same sky brightness - two people can have very different experience if they have different transparency conditions.

How about SQM?

I find SQM to be useful in many ways. First - it is not estimate, it is measured quantity. It uses same system we use to compare brightness between astronomical objects (magnitude system). It is useful for imagers because they can estimate signal levels from SQM given their equipment and so on ...

[Alan White]

If I am honest all of the terms befuddle me and are in a way meaningless.
Its more a gut feeling of more or lower light pollution visible to my eyes.

I have to say I am with @niallk on not liking insecurity lights, but thats well documented on this forum.

[JeremyS]

My rule of thumb is “can I see the Milky Way from that site or not?”. Assuming no moon good transparency. Perhaps qualified with roughly how often: dead cert all the time, about half the time, or never.

[skyhog]

Yes, I very much ignore these scales. I find estimating light pollution a simple exercise. I have been under skies that are probably about as dark as its possible to get and looked up at the blazing skies in the world's major cities at the other end of the scale. I think being able to see the milky way is a good indicator, as mentioned, and faintest star magnitude in general says a lot. In truth we all know a good sky when we see one.😉

[ollypenrice]

Various things can cause a gentlemen to bortle.  Too much ruby Port at his club, of an afternoon, particularly after Champagne with the fish, can bring it on. These ghastly, gassy foreign beers can cause one to bortle as well - and I'm sure that imbibing Coca-Cola would be a dead cert, though a gentleman wouldn't do that. I also remember one chap's 1932 Blower Bentley bortling at Balmoral after getting a partridge stuck in its fuel filter.

Olly

[skyhog]

1 minute ago, ollypenrice said:

Various things can cause a gentlemen to bortle.  Too much ruby Port at his club, of an afternoon, particularly after Champagne with the fish, can bring it on. These ghastly, gassy foreign beers can cause one to bortle as well - and I'm sure that imbibing Coca-Cola would be a dead cert, though a gentleman wouldn't do that. I also remember one chap's 1932 Blower Bentley bortling at Balmoral after getting a partridge stuck in its fuel filter.

Olly

Are you sure you haven't had a crafty bortle before typing that Olly... 🤔

[jetstream]

After SQMing all over this area I now use the Milky Way appearance as a great guide. When its jagged mottled appearance with dark lanes and spurs show, this correlates with 21.8-21.9 SQM. The SQM is a super valuable tool however I truly dislike the Bortle scale.

[ollypenrice]

3 minutes ago, skyhog said:

Are you sure you haven't had a crafty bortle before typing that Olly... 🤔

Certainly... ahem, excuse me... certainly not.

It was Hubert (our bloodhound.)

[Sunshine]

It seems there are others who feel the same as I when it comes to bortle. A rebellion against the bortle scale is on the horizon and I shall gladly lead us to freedom!! face paint and all.

I introduce the Milky Way visibility scale. Now I have to figure out the levels of visibility and how to determine them. 

 

Edited December 17, 2021 by Sunshine

[DaveS]

I see jagged spurs, dust lanes and glitter in the Milky Way here, with structure down to the southern horizon, though it is taking longer for my eyes to dark adapt now, roughly since I had some severe eye drops in the local hospital to check my vitreous humour (I had bright halos around any light source for hours afterwards).

One night a few weeks ago when I went out to close up the 'scope the sky was spectacular (Helped by my eyes having dark adapted while in bed), Auriga glittered with clusters and I'm pretty sure I saw (Glimpsed?) M33 with direct vision. But won't put my hand on a bible to it 😆.

[vlaiv]

12 minutes ago, Sunshine said:

It seems there are others who feel the same as I when it comes to bortle. A rebellion against the bortle scale is on the horizon and I shall gladly lead us to freedom!! face paint and all.

I introduce the Milky Way visibility scale. Now I have to figure out the levels of visibility and how to determine them. 

 

I actually don't mind it at all

I'll probably be covert agent of Bortle regime that infiltrated rebellion?

[Sunshine]

2 minutes ago, vlaiv said:

I actually don't mind it at all

I'll probably be covert agent of Bortle regime that infiltrated rebellion?

Not covert at all as you’ve just revealed yourself! Now I see why you wear a mask in your avatar.

Edited December 17, 2021 by Sunshine

[markse68]

I base my sky quality assessment on how many stars in the plough i can see. What’s this milkyway you all mention? 😉

[Mr Spock]

My sky is Bortle 6. Feels more like 8 at times...

[ollypenrice]

I must confess that, after an excellent dinner at my club, I found myself obliged to take the Clapham omnibus to my London chambers. The only available seat being next to the authoress of a well-known etiquette book, I beseated myself next to her and, unfortunately, bortled loudly.  I looked at the lady earnestly and said, in my finest stage whisper, 'Think nothing of it, my dear. They'll all assume it was I.'

Olly

[ONIKKINEN]

Bortle is a quick and "thereabouts" kind of way to describe skies, but SQM is better. But try explaining SQM to someone not in the hobby and youll find a convenient 1 to 9 scale is much easier to explain.

The word itself does sound pretty "3AM conversation in a taxi".

[badhex]

17 hours ago, ONIKKINEN said:

Bortle is a quick and "thereabouts" kind of way to describe skies, but SQM is better. But try explaining SQM to someone not in the hobby and youll find a convenient 1 to 9 scale is much easier to explain.

The word itself does sound pretty "3AM conversation in a taxi".

+1 for this - the Bortle scale is obviously quite rough and ready but it's not a bad 'finger in the air' description, especially for newer members of the hobby.

While looking at a sky is obviously the most helpful, the Bortle scale is helpful in reference to somewhere you've never been, say a holiday where you're perhaps planning to go with a small telescope.

SQM is obviously a much more accurate and scientific measurement but perhaps not as easy to remember what constitutes a decent dark sky or not.