|Sky Quality Meter
||"You've got to kick at the brightness 'til it bleeds starlight."
- with apologies to Bruce Cockburn
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
- 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.
Reports including the SQM:
Light pollution maps / databases:
- Night Sky Photometry with Sky Quality Meter
by Pierantonio Cinzano.
- "Contributions of artificial lighting sources on light pollution in Hong Kong measured through a night sky brightness monitoring" article by
Chun Shing Jason Pun, Chu Wing So, Wai Yan Leung, Chung Fai Wong.
- Human Contrast Threshold and Astronomical Visibility paper by Andrew Crumey.
- Report on sky colour: Red is the new black; Chris Kyba and colleagues
- Documenting Local Night Sky Brightness report, Jennifer Birriel of MSU.
Measure Night Sky Brightness at Various Zenith Angles report, Jennifer Birriel of MSU.
- "Night sky photometry and spectroscopy performed at the Vienna University Observatory" published in the "Journal of Quantitative Spectroscopy and Radiative Transfer"
- "The night sky brightness at Potsdam-Babelsberg including overcast and moonlit conditions" published in the
"Journal of Quantitative Spectroscopy and Radiative Transfer"
- "Worldwide variations in artificial skyglow" by Christopher C. M. Kyba, Kai Pong Tong, and more.
Published in Nature.com : Scientific Reports.
- "Intercomparisons of Nine Sky Brightness Detector"
by Peter den Outer, Dorien Lolkema, Marty Haaima, Rene van der Hoff, Henk Spoelstra, and Wim Schmidt.
Published in 2014 The National Center for Biotechnology Information.
Useful Light pollution links:
- Unihedron Database of Sky Quality Meter readings from around the world.
- Globe at Night : Maps and Data.
- Light Pollution Map by Jurij Stare which displays light
radiance from NOAA and SQM data from the Unihedron reading database.
- SQM-Network is a free network of connected SQM meters from around the world. [No longer maintained].
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