Unihedron Sky Quality Meter with Lens - Narrow Field of View / USB Connection # SQM-LU

Our Price: $189.95
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In stock (4 Available)
Ships by Next Business Day
Our Product ID: PAOA-UN-SQM-LU
Manufacturer SKU: SQM-LU
Item Can Ship: Worldwide
Unihedron Sky Quality Meter with Lens - Narrow Field of View / USB Connection # SQM-LU

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Product Details

A USB SQM model for night-time sky brightness monitoring! The "Sky Quality Meter" measures the brightness of the night sky in magnitudes per square arcsecond. Designed by Dr. Doug Welch and Anthony Tekatch, the Unihedron Sky Quality Meter offers unprecedented sensitivity in a handheld meter.


  • Find out how good the night or site REALLY is.
  • Compare the sky brightness at different sites quantitatively.
  • 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 Chart.
  • CCD users can make a correlation between the SQM reading and when the background reaches some ADC level.


  • 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.


  • USB connectivity.
  • Included applications for reading data in Perl.
  • 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.
  • Size 3.6 x 2.6 x 1.1 in.
  • Maximum light sampling time: 80 seconds.
  • Minimum light sampling time: 1 seconds.
  • Specifications are subject to change without notice.

What You Get:

  • SQM-LU unit
  • SQM-LU users manual
  • CD with PDF manual and example software
  • 15ft USB cable
  • Calibration sheet indicates unit USB serial number, and calibration values

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