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Unihedron Sky Quality Meter

3.0 out of 5 stars
1 customer reviews

Price: $119.00

  • Manufacturer: Unihedron
  • MPN: SQM
  • SKU: SQM
  • Availability: In Stock

Finally, an affordable meter for measuring sky brightness for astronomers! The "Sky Quality Meter" measures the brightness of the night sky in magnitudes per square arcsecond. Unprecedented sensitivity in a handheld meter! Designed by Dr. Doug Welch and Anthony Tekatch.

NOTE:  It is desirable to have a narrow field of view when determining the sky brightness in crowded areas where street lamps, buildings, trees, etc. are present. A more accurate view of a small area of the sky can be found with a narrow FOV.  The main difference the SQM and SQM-L is the field of view. The SQM-L (with lens) is an improvement over the SQM. The lens collects more light from a smaller cone so that the meter is not affected from lights or shading on the horizon.  The SQM-L is better suited for astronomy and dark sky enthusiasts. It has a lens to narrow the field of view so that street lights and buildings or trees do not affect the reading very much.



  • 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 Clock.
  • CCD users can make a correlation between the SQM reading and when the background reaches some ADC level.


  • 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.



  • Operates from 9V battery (included).
  • Size 3.8 x 2.4 x 1 in.
  • Maximum light sampling time: 8 0 seconds.
  • Specifications are subject to change without notice.


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3.0 out of 5 stars

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Most Helpful Customer Reviews

Sky Quality Meter

By Michael Harrison on October, 17th 2009

New to astronomy I live in light polluted Southern California. I have had a great deal of trouble finding constellations from my home. When viewing from moderately dark sites I do better be I wanted to quantify my situation. I purchased the meter so that I can understand my situation, NELM 3.3, and when I get to a dark site I can quantify the improvements. I have seen maps marked with magnitudes to help determine these values. I found that I could not find enough stars to recognize the patterns. The meter helped me understand why. The meter works but could use some interface improvements. The guard on the button makes the button hard to push and the readout is on the same side of the unit as the detector, hence, one can not watch it work.

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