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Can some one explain these MAPS. Are the blue areas the dark sites for example...

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Sure.
According to the CSC site, this is the breakdown by color:

White: Artificial/Natural Sky Brightness >27.0
Sky Brightness mags/sq arcsec V Band: <18.38
Bortle Scale 8 or 9

Red: Artificial/Natural Sky Brightness 9.0 to 27.0
Sky Brightness mags/sq arcsec V Band: 19.50 to 18.38
Bortle Scale 6 or 7

Orange: Artificial/Natural Sky Brightness 3.0 to 9.0
Sky Brightness mags/sq arcsec V Band: 20.49 to 19.50
Bortle Scale 5

Yellow: Artificial/Natural Sky Brightness 1.0 to 3.0
Sky Brightness mags/sq arcsec V Band: 21.25 to 20.49
Bortle Scale 4.5

Green: Artificial/Natural Sky Brightness 0.33 to 1.0
Sky Brightness mags/sq arcsec V Band: 21.69 to 21.25
Bortle Scale 4

Blue: Artificial/Natural Sky Brightness 0.11 to 0.33
Sky Brightness mags/sq arcsec V Band: 21.89 to 21.69
Bortle Scale 3

Grayish Black (Darkest color seen on my post above yours)
Sky Brightness mags/sq arcsec V Band: 21.99 to 21.89
Artificial/Natural Sky Brightness 0.01 to 0.11
Bortle Scale 2

Black: Artificial/Natural Sky Brightness <0.01
Sky Brightness mags/sq arcsec V Band: 22.00 to 21.99
Bortle Scale 1

HTH
Matt

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