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Sky Quality Meter Ethernet


An ethernet-enabled Sky Quality Meter model for night-time sky brightness monitoring

The Sky Quality Meter - LE measures the brightness of the night sky in magnitudes per square arcsecond.

Enables continual, connected measuring of sky brightness for astronomers.


  • Find out how good the night or site REALLY is.
  • Compare the sky brightness at different sites.
  • Document the evolution of light pollution in your area.
  • Set planetarium dome illumination to mimic the skies people are likely to experience elsewhere in the city.
  • Monitor sky brightness through the night, night-to-night, and year-to-year.
  • 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.
What's In the Box?
  • SQM-LE unit
  • International Power adapter
  • USB flash drive containing the users manual, operation software (UDM), and example software. The can also be found online.
  • 6ft Ethernet cable (straight through for connection to hub/router)
  • Ethernet crossover cable or adapter (for connection directly to PC)
  • Calibration sheet indicates unit MAC address, and calibration values
  • Weatherproof housing
  • Ethernet connectivity
  • Included applications for reading data in Java, C, Perl, Python.
  • 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. Annotated FOV spec. Comparison chart.
  • Operates from 5-6VDC adapter (included).
  • Size 92mm x 66mm x 28mm
  • Maximum light sampling time: 80 seconds.
  • Minimum light sampling time: 1 seconds
  • Sky brightness reported in visual magnitudes per square arcsecond.
  • Infrared blocking filter restricts measurement to visual bandpass.
  • Sensor temperature, model number, and serial number are provided.
  • Precision readings at even the darkest sites.
  • Field-upgradeable firmware
  • Open protocol document