prime grid meridian

prime grid meridian

[′prīm ′grid mə‚rid·ē·ən]
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The reference meridian of a grid; in polar regions it is usually the 180-0° geographic meridian, used as the origin for measuring grid longitude.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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