A USB SQM model for night-time sky brightness monitoring! An affordable meter for continual, connected measuring of sky brightness for astronomers! The "Sky Quality Meter - LU" measures the brightness of the night sky in magnitudes per square arcsecond. 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.

Features:

• Sky brightness reported in visual magnitudes per square arcsecond.
• Infrared blocking filter restricts measurement to visual bandpass.
• Sensor temperature, model number, and serial number are provided.
• Precision readings at even the darkest sites.
• Field-upgradeable firmware.
• Open protocol document.

• USB connectivity
• Included applications for reading data in Perl.
• 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.
• Size 3.6 x 2.6 x 1.1 in.
• Maximum light sampling time: 80 seconds.
• Minimum light sampling time: 1 seconds.
• Specifications are subject to change without notice.

SQM-LU unit SQM-LU users manual CD with PDF manual and example software 15ft USB cable Calibration sheet indicates unit USB serial number, and calibration values

Details: SQM-LU Users manual Frequently Asked Questions Optional outdoor housing SQM mailing list SQM users links Magnitudes/arcsecond² to cd/m² converter Conversion Calculator - NELM (V) to MPSAS (B) systems by K. Fisher Database of users readings Software Downloads: SQM Reader by Knightware Contents of CD including other language examples (Perl, Python)

Useful links: Downloads or users contributions Report on SQM by Pierantonio Cinzano Light pollution report by Richard Berry Radiometry and photometry in astronomy By Paul Schlyter Notes from sci.astro.amateur Surface Brightness by Tony Flanders The Bortle Dark-Sky Scale by John E. Bortle Outdoor Lighting and Crime by Dr. Barry Clark "A Rationale for the mandatory limitation of outdoor lighting" by Barry A. J. Clark, PhD [revised Feb 28, 2008] GLOBE at Night. What does your nighttime sky look like? Applet Starry Night Lights : Night Sky Friendly Outdoor Lighting Products SkippySky Astro-Weather Forecast Unihedron supports the goals of the International Dark-Sky Association.