SK-42 reference system
geodetic reference ellipsoid
The SK-42 reference system is a geodetic datum established in the Soviet Union in 1942 as Systema koordinat (Russian: Система координат 1942 года).
It was used in geodetic calculations, notably in military mapping and determining state borders.
SK-42 is based on the Krasovsky 1940 ellipsoid, a locally best fitting reference ellipsoid named after Feodosy Krasovsky. It has a semi-major axis (equatorial radius) a of 6,378,245 m, and an inverse flattening 1/f of 298.3
SK-42 served as a foundation for developing the SK-63 reference system which was created and used primarily for civilian and industrial development purposes.
It was later linked to the geocentric coordinate system PZ-90 via a datum transformation.
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Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Dec 3, 2025. The linked authority identifier is Q379834. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1942 and 1940.
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This entry incorporates text from “SK-42 reference system” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.