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Unihedron Sky Quality Meter with Lens - Narrow Field of View SQM-L


An affordable meter for measuring sky brightness for astronomers! The "Sky
Quality Meter" measures the brightness of the night sky in magnitudes per
square arc second and 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. - 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 ~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. (See photo 2) - Operates from 9V battery
(included). - Size 3.6 x 2.6 x 1.1 in. - Maximum light sampling time: 80


  • Affordable meter for measuring night sky brightness for astronomers
  • Full Width Half Maximum (FWHM) ~20
  • Size 3.6 x 2.6 x 1.1 in.; 9v battery included
  • Infrared blocking filter restricts measurement to visual bandpass
  • Compare the sky brightness at different sites quantitatively

Product Details

  • Brand: Unihedron
  • Item Weight: 13 ounces
  • Package Dimensions: 5 x 5 x 3 inches
  • Shipping Weight: 13 ounces
  • Date First Available: July 14, 2011

Shipping & Handling

Most orders are shipped within one business day with standard shipping and tracking number. Tracking information will be automatically uploaded as soon as the item has been shipped.

Please make sure to provide the correct shipping address during checkout as the address cannot be changed after checkout. We are not responsible for any incorrect or undeliverable addresses.

We do not ship to AK, HI, PO boxes, or APO addresses.

Return Policy

All returns accepted within 14 days after receiving the item, refund given as money back (no exchanges permitted), return shipping to be paid by buyer. 15% restock fee will be charged for all returns. Buyer is responsible for return shipping on any item that is not damaged.

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