Unihedron Sky Quality Meter

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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. Designed by Dr. Doug Welch and Anthony Tekatch, the Unihedron Sky Quality Meter offers unprecedented sensitivity in a handheld meter.
Uses:
- 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.
Features:
- 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.
Specifications:
- The Half Width Half Maximum (HWHM) of the angular sensitivity is ~42° (See photo 2)
- 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.
Note: Unlike the SQM-L, this SQM does not come with a cloth storage bag because the lensplate is plastic and might get scratched up by the cloth rubbing against it all the time. It is better to store the SQM in the small cardboad box that it comes with so that nothing rubs on the lensplate.
Useful Resources
- User Manual: SQM Instruction Sheet (PDF format)
- Frequently Asked Questions
- SQM Comparison Chart
Other Information
- Country of Manufacture: Canada
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. Designed by Dr. Doug Welch and Anthony Tekatch, the Unihedron Sky Quality Meter offers unprecedented sensitivity in a handheld meter.
Uses:
- 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.
Features:
- 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.
Specifications:
- The Half Width Half Maximum (HWHM) of the angular sensitivity is ~42° (See photo 2)
- 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.
Note: Unlike the SQM-L, this SQM does not come with a cloth storage bag because the lensplate is plastic and might get scratched up by the cloth rubbing against it all the time. It is better to store the SQM in the small cardboad box that it comes with so that nothing rubs on the lensplate.
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. Designed by Dr. Doug Welch and Anthony Tekatch, the Unihedron Sky Quality Meter offers unprecedented sensitivity in a handheld meter.
Uses:
- 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.
Features:
- 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.
Specifications:
- The Half Width Half Maximum (HWHM) of the angular sensitivity is ~42° (See photo 2)
- 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.
Note: Unlike the SQM-L, this SQM does not come with a cloth storage bag because the lensplate is plastic and might get scratched up by the cloth rubbing against it all the time. It is better to store the SQM in the small cardboad box that it comes with so that nothing rubs on the lensplate.
Useful Resources
- User Manual: SQM Instruction Sheet (PDF format)
- Frequently Asked Questions
- SQM Comparison Chart
Other Information
- Country of Manufacture: Canada
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Unihedron Sky Quality Meter


















