Bortle Scale "Modification" - Forums

Topic starter

1 day ago

This is not a rant, nor is my intention overtly negative. It’s just an observation …

Lately, I’ve been noticing a lot more “Bortle 1” sites specified in image statistics. And not that I am familiar with these sites, but I have also seen associated SQM readings that seem not to comport with that which has long been considered top-of-the-scale metrics. It used to be that a “Bortle 1” site was truly hallowed ground with a best SQM reading at 21.99 or 22.00. If memory serves me, “Bortle 2” was between 21.90 and 21.99; “Bortle 3” somewhere between 21.80 and 21.90. Even “Bortle 4” was tough to hit at somewhere above 21.70 ….

Wikipedia now shows “Bortle 1” as a sky darkness at 21.76 and above, which can explain why so many sites now have a gold star on their foreheads.

Please don’t get me wrong: Transparency and Seeing being equal, looking up at a 21.76 night sky is a wonder to behold; however, 22.00 is indeed a scary experience. Good luck finding your hand in front of your face, not to mention the distinct possibility of a seasoned observer looking up and being momentarily disoriented ….

I guess it’s the way of today’s world. Participation Trophies and a short porch in Right Field at Yankee Stadium ….

Just saying ….

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Quinn Groessl

IOTD Staff

1 day ago

Who cares? It’s a scale based on largely arbitrary numbers.

If someone uploaded identical images to this site. Identical an in every last pixel looks the same. One was taken in a bottle 2 and one was taken in a bottle 1. Would that make either of them any look any better?

Scott Badger

1 day ago

Quinn Groessl · Sep 19, 2026 at 12:40 PM
Who cares? It’s a scale based on largely arbitrary numbers.
If someone uploaded identical images to this site. Identical an in every last pixel looks the same. One was taken in a bottle 2 and one was taken in a bottle 1. Would that make either of them any look any better?

If you’re picking a travel destination for its dark skies, it matters.

Cheers,

Scott

andrea tasselli

Frequent contributor

1 day ago

Bortle scale is a subjective, visual graduation of the night sky. Photometric magnitude is a way later addition whose consistency may be questionable. On top of Mauna Kea, with the right weather, you can get down to 22m x sqa.

Jay Hovnanian

Topic starter

23 hours ago

How we rate the numbers is indeed a subjective matter — you can label your site however you want; however, the SQM numbers relating to the Bortle Scale are not arbitrary or subjective. They actually represent how dark a night sky is or isn’t. So, as @Scott Badger says, if you are looking to visit (or choose a Hosting Facility) and sky darkness is important to you, the numbers will actually matter ….

On the other hand, I personally believe that Seeing is an equal (or perhaps greater within reason) component to our evaluating. For example: I would rather image under a “Bortle 3” night sky with sub-arcsecond Seeing than a “Bortle 1” site under The Jet Stream.

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Scott Badger

23 hours ago

Jay Hovnanian · Sep 19, 2026, 02:57 PM
How we rate the numbers is indeed a subjective matter — you can label your site however you want; however, the SQM numbers relating to the Bortle Scale are not arbitrary or subjective. They actually represent how dark a night sky is or isn’t. So, as @Scott Badger says, if you are looking to visit (or choose a Hosting Facility) and sky darkness is important to you, the numbers will actually matter ….
On the other hand, I personally believe that Seeing is an equal (or perhaps greater within reason) component to our evaluating. For example: I would rather image under a “Bortle 3” night sky with sub-arcsecond Seeing than a “Bortle 1” site under The Jet Stream.

Completely agree with Jay’s seeing preference, though for me at least, I think the bad seeing factors are more local than the jet stream; thermal mixing at ground level and near ground level due to mountainous terrain and large temperature changes.

Cheers,
Scott

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Tony Gondola

Frequent contributor

Exemplary contributor

22 hours ago

Jay Hovnanian · Sep 19, 2026, 02:57 PM
How we rate the numbers is indeed a subjective matter — you can label your site however you want; however, the SQM numbers relating to the Bortle Scale are not arbitrary or subjective. They actually represent how dark a night sky is or isn’t. So, as @Scott Badger says, if you are looking to visit (or choose a Hosting Facility) and sky darkness is important to you, the numbers will actually matter ….
On the other hand, I personally believe that Seeing is an equal (or perhaps greater within reason) component to our evaluating. For example: I would rather image under a “Bortle 3” night sky with sub-arcsecond Seeing than a “Bortle 1” site under The Jet Stream.

Yes, I totally agree with that but some don’t really need good seeing, just a dark sky.

Tony Gondola

Frequent contributor

Exemplary contributor

22 hours ago

Scott Badger · Sep 19, 2026, 02:08 PM
Quinn Groessl · Sep 19, 2026 at 12:40 PM
Who cares? It’s a scale based on largely arbitrary numbers.
If someone uploaded identical images to this site. Identical an in every last pixel looks the same. One was taken in a bottle 2 and one was taken in a bottle 1. Would that make either of them any look any better?
If you’re picking a travel destination for its dark skies, it matters.
Cheers,
Scott

And of you are choosing a remote hosting site….

donld

Frequent contributor

18 hours ago

Starfront is a hoot. They are a couple hundred miles from Bortle 1 and show why they are not in that class in the opening video on their web site. Then they put bortle 1 on the same opening page. Or did last I looked.

There’s also one of the oldest hobby observatories in California that claims 200 nights a year which the local astrophotographers laugh at.

Probably every commercial remote site is great, but most seem to lie about conditions,Either directly or by implication. Many have enough population growth in the area to impact brightness.

Big Bend Remote Observatories is the only clearly Bortle 1 observatory I found in my search. But perhaps there are one or two others I missed. That location, which includes Big Bend National Park, is the largest dark sight in the Continental US. Its latitude is also in the ideal range. It’s extremely remote.

But if I lived somewhere I could drive a few hours to a good remote observatory I would probably choose that local site over others. Since I was shipping regardless of choice my gear it went to the remote desert.

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