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The Bortle dark-sky scale (usually referred to as simply the Bortle scale) is a nine-level numeric scale that measures the night sky's brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution .
John E. Bortle is an American amateur astronomer. He is best known for creating the Bortle scale to quantify the darkness of the night sky. Bortle has made a special study of comets. He has recorded thousands of observations relating to more than 300 comets. From 1977 until 1994 he authored the monthly '"Comet Digest" in Sky and Telescope magazine.
See the Bortle scale.) There is even variation within metropolitan areas. For those who live in the immediate suburbs of New York City, the limiting magnitude might be 4.0. This corresponds to roughly 250 visible stars, or one-tenth of the number that is visible under perfectly dark skies.
The North American Numbering Plan (NANP) divides the territories of its members into geographic numbering plan areas (NPAs). Each NPA is identified by one or more numbering plan area codes (NPA codes, or area codes), consisting of three digits that are prefixed to each local telephone number having seven digits.
The South Carolina Public Service Commission on Nov. 28 announced the new area code will be assigned to new 10-digit telephone numbers. All existing customers will retain their 864 area code, said ...
Mobile phones use geographic area codes (two digits): after that, all numbers assigned to mobile service have nine digits, starting with 6, 7, 8 or 9 (example: 55 15 99999–9999). 90 is not possible, because collect calls start with this number.
It can’t hurt to be wary of possible scam phone numbers with the following international area codes. Scam phone numbers: International Area Codes with a +1 Country Code 232—Sierra Leone
Many just call it the "Bortle scale" (some with "Bortle Scale"). And some "Bortle Scale of Light Pollution". There's very little evidence that this should be treated as a proper name; it's just a scale named for a guy. Probably a better title suggestion would have been "Bortle scale", yes? Dicklyon 06:12, 4 April 2013 (UTC) Books are also big ...