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CPRE 2019 Star Count- The results are in.....

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....and a bit baffling!

The first three 'Truely Dark Sky Sites' I checked were in towns........

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Clearly the 'data' is not being checked.

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York city centre, Stoke On Trent, North Shields- to name but a few, are also good observing sites.......

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IMO there aren't enough results to give any significant statistical information.  The variation in results far exceeds anything useful.

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Even more strange (to me!) is that if you turn on the 'Night Blight' layer some of our local so called dark sites have no measurements in them! So how do they conclude that? Mind you, I'm not sure exactly what that layer is representing.

Ian

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12 hours ago, Gina said:

IMO there aren't enough results to give any significant statistical information.  The variation in results far exceeds anything useful.

Agreed, around me in the outskirts of SW London if the results are to be believed the sky goes from Dark skies to Very severe light pollution......

In reality it varies a lot due to the atmosphere, time in the evening, where the moon is, and where in the sky the object you are looking at is (if it is fairly overhead you are in business). With a CCD I can easily get below mag15 so I'm happy.

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There is another SGL thread on this:

I agree that the data is very inconsistent and rather inconclusive.

 

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There's a location near here where someone reported 45 stars.  I'm struggling to credit that, I have to admit.

It might be interesting to look at what kind of magnitude stars we're getting down to for that sort of figure.

James

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9 hours ago, JamesF said:

There's a location near here where someone reported 45 stars.  I'm struggling to credit that, I have to admit.

It might be interesting to look at what kind of magnitude stars we're getting down to for that sort of figure.

James

Assuming he/she went from brightest down in order without missing any at all (unrealistic I would say!) they got to mag 4.9 if my list of stars and their brightness in Orion are correct.

Maybe they spotted a dim star and calculated they could in theory see all stars that were brighter than that using a list, or perhaps they counted all the stars they could see in the sky instead? ?

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 If I remember, the aim was to count the stars that you could see with the naked eye within the area defined by the 4 "corner" stars Betelgeuse, Saiph, Rigel and Bellatrix, but excluding those 4 stars from the count ?

In my best count (25 stars) I got 32 and 52 Orionis which are magnitude 4.2 and 5.3 respectively I believe. My overhead limit on a dark night (such as the one when I got my best count) is around magnitude 5.5.

On a night of worse seeing the star count declined dramatically to under 10 so seeing, visual acuity and simply knowing where some of the fainter stars are all affect the result. My light pollution levels remained the same.

 

 

 

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