An Etymological Dictionary of Astronomy and Astrophysics
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A standard system of measurement using decimal units, in which the units of length, time, and mass are meter, second, and kilogram respectively.

→ metric; → system.

A system of → magnitudes, each of them characterized by a set of well-defined → passbands (or → filters) with known → response curves. The system is defined by the values given for the → standard stars. See also:
→ AB magnitude system, → five-color system, → Stromgren system, → JHK system, → UBV system, → uvby system.

→ photometric; → system.