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Sky Brightness Meter

The brightness of the sky is measured in units of magnitude per square arcsecond (mpsas) as shown on the left axis. The approximate naked eye limiting magnitude (nelm) is shown on the right axis. Dates and times are EST/EDT. The meter is located on the roof of Ladd Observatory and aimed at the zenith. When the sky is darker than 6 mpsas a new measurement is taken every minute. The graph is updated every three minutes.

Sky brightness graph

For detailed information about the Unihedron SQM-LE meter, please see the specifications.