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Sky Quality Meter


An easy to use meter for measuring the brightness of the night sky

The Sky Quality Meter - L measures the brightness of the night sky in magnitudes per square arcsecond. Perfect for checking how dark you night sky is and for dark sky reserve projects.

Unprecedented sensitivity in a handheld meter.


  • Find out how good the night or site REALLY is.
  • Compare the sky brightness at different sites.
  • Monitor sky brightness through the night, night-to-night, and year-to-year.
  • Set planetarium dome illumination to mimic the skies people are likely to experience elsewhere in the city.
  • Determine which nights show the greatest promise for finding the 'faintest fuzzies'.
  • Calibrate the effect of sky brightness on qualitative measures such as the Bortle Scale.
  • Investigate how sky brightness correlates with the solar cycle and month-to-month sunspot activity.
  • Help provide local ground truth for future sky brightness prediction with the Clear Sky Clock.
  • CCD users can make a correlation between the SQM reading and when the background reaches some ADC level.
  • The Half Width Half Maximum (HWHM) of the angular sensitivity is ~10°. The Full Width Half Maximum (FWHM) is then ~20°. The sensitivity to a point source ~19° off-axis is a factor of 10 lower than on-axis. A point source ~20° and ~40° off-axis would register 3.0 and 5.0 magnitudes fainter, respectively. Comparison chart.
  • Operates from 9V battery (included).
  • Size: 92 x 67 x 28mm
  • Weight: 140g
  • Maximum light sampling time: 80 seconds.
    • Audible signal while measurement is in progress.
    • Sky brightness displayed in visual magnitudes per square arcsecond.
    • Infrared blocking filter restricts measurement to visual bandpass.
    • Temperature in both Celsius and Fahrenheit as well as model number and serial number can be displayed with different button press sequence.
    • Precision readings at even the darkest sites.
    • Power-saving features designed in for maximum battery life.
    • Reverse battery protection.