Photo by Doug Welch
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Latest News

New Brunswick, Canada: Grade 8 students Holly Ayles and Emily Baxter are national winners in the recent International Statistical Literacy Poster Competition. Their poster will go to international level in Dublin Ireland later in August.

A Survey of Light Pollution in Hong Kong.
Researchers at the Department of Physics of The University of Hong Kong completed their light pollution survey and collected near 2,000 night sky brightness data sets from SQMs at more than 220 observation sites around Hong Kong during the past 15 months.
Full report here.

GLOBE at Night: Shed Light on Light Pollution! Podcast. Connie Walker of the NOAO discusses the Globe at Night project as part of the 365 days of astronomy during the Year of Astronomy.

Dark Skies Awareness, an IYA2009 cornerstone project helps people appreciate the dark sky with 11 projects including the GLOBE at Night campaign using both visual and SQM readings.
Hong Kong light pollution survey
A survey of light pollution in Hong Kong using various tools including the Sky Quality Meter
Earth Hour plot Rick Wagner reports on his Earth Hour findings
Available Now
Sky Quality Meter-L Sky Quality Meter with Lens for Narrow Field-of-View.
Unihedron receives the Executive Director Special Award and the Certificate of Appreciation for its exhibit at "The Night: Why Dark Hours Are So Important" symposium in Washington DC.
Downloads of users contributions.
Database of Sky Quality Meter readings from around the world.
Independent report on the Sky Quality Meter by Pierantonio Cinzano.
Depiction of response field and holding position.
Sky Quality Meter "You've got to kick at the brightness 'til it bleeds starlight."
- with apologies to Bruce Cockburn
Sky Quality Meter

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

  • 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.

  • The Half Width Half Maximum (HWHM) of the angular sensitivity is ~42°. Comparison chart.
  • Operates from 9V battery (included).
  • Size 3.8 x 2.4 x 1 in.
  • Maximum light sampling time: 80 seconds.
  • Specifications are subject to change without notice.

Unihedron supports the goals of the International Dark-Sky Association .

Details: faceplate Reports including the SQM: Light pollution maps / databases: Useful Light pollution links:

SQM tripod adaptor option


This adaptor kit was designed specifically for the SQM (non-lens/original) so that the battery compartment is accessible with the adaptor in place.

The adaptor screws into the back of the SQM and allows the meter to be mounted on a tripod with a 1/4-20 thread.

The kit includes one tripod adaptor, 3D-printed plastic, and two longer screws (to replace two short screws already in the meter).

3D part view


You may also be interested in; our narrow-field sky meter (SQM-L), or our Ethernet conected sky meter (SQM-LE), or our USB connected model (SQM-LU).
Compare models.
Ready to buy?

Price $119.99US plus Shipping & Handling.


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