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.

SQM user Henk Spoelstra of Lumineux Consult has set up a network of SQM-LE units to monitor sky brightness in the Netherlands. You can view his nomograph of light pollution factor and readings plot here.

Clear Sky Detection experiment
Here is an experiment to try to identify a clear sky using the SQM-LE/LU by observing the fluctuations in light level caused by clouds.
Details here.

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.

Knightware, makers of "Deep-Sky Planner", have released SQM Reader Pro for Windows and the SQM-LE. This low-cost package adds graphing, statistical calculations, extended data storage and transmission capabilities to the basic feature set of existing "SQM Reader" software.

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
2007-04-02
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.
Sky Quality Meter - LE "You've got to kick at the brightness 'til it bleeds starlight."
- with apologies to Bruce Cockburn
Sky Quality Meter-LE

An ethernet-enabled SQM model for night-time sky brightness monitoring!

An affordable meter for continual, connected measuring of sky brightness for astronomers!

The "Sky Quality Meter - LE" measures the brightness of the night sky in magnitudes per square arcsecond.

Designed by Dr. Doug Welch and Anthony Tekatch

Live SQM-LE results from Unihedron office
Live SQM-LE results from the Unihedron office
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:

  • 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

Specifications:
  • Ethernet connectivity
  • Included applications for reading data in Java, C, Perl, Python.
  • 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.
  • Operates from 5-6VDC adapter (included).
  • 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.

What you get:
  • SQM-LE unit
  • International Power adapter
  • SQM-LE users manual
  • CD with PDF manual and example software
  • 6ft Ethernet cable (straight through for connection to hub/router)
  • 6ft Ethernet crossover cable (for connection directly to PC)
  • Calibration sheet indicates unit MAC address, and calibration values
Ready to buy?


Price $249.99US plus Shipping & Handling.

Dealers


What you get (with housing):
  • SQM-LE unit
  • International Power adapter
  • SQM-LE users manual
  • CD with PDF manual and example software
  • 6ft Ethernet cable (straight through for connection to hub/router)
  • 6ft Ethernet crossover cable (for connection directly to PC)
  • Calibration sheet indicates unit MAC address, and calibration values
  • Weatherproof housing
Ready to buy?


Price $289.94US plus Shipping & Handling.

Dealers


What you get (with housing and PoE):
  • SQM-LE unit
  • International Power adapter
  • SQM-LE users manual
  • CD with PDF manual and example software
  • 6ft Ethernet cable (straight through for connection to hub/router)
  • 6ft Ethernet crossover cable (for connection directly to PC)
  • Calibration sheet indicates unit MAC address, and calibration values
  • Weatherproof housing
  • Power over Ethernet kit
Ready to buy?


Price $349.94US plus Shipping & Handling.

Dealers


Details: Software Downloads: Reports including the SQM:
  • 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.   Science direct  arxiv.
  • Human Contrast Threshold and Astronomical Visibility paper by Andrew Crumey.
  • Report on sky colour: Red is the new black; Chris Kyba and colleagues PDF.
  • 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" Science Direct  arXiv.
  • "The night sky brightness at Potsdam-Babelsberg including overcast and moonlit conditions" published in the "Journal of Quantitative Spectroscopy and Radiative Transfer" Science Direct  arXiv.
  • "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.
  • Calibration of SQM-L photometers for the NixNox project, Zamorano Calvo, Jaime and Munoz MarĂ­n, Victor Manuel (2010), eprints.ucm.es/12262/
  • Zamorano, Jaime y Munoz Marin, Victor Manuel (2010), Calibration of SQM-L photometers for the NixNox project. [ LICA report; no. #01], eprints.ucm.es/12262/
  • Zamorano, Jaime & Ruiz Carmona, Roque (2013), Sky Quality Meter cross-calibration for the NixNox project. [ LICA report; no. #03], eprints.ucm.es/18015/
  • Nievas Rosillo, Miguel & Zamorano, Jaime (2014), *PySQM the UCM open source software to read, plot and store data from SQM photometers*, eprints.ucm.es/25900/
  • Zamorano, Jaime, Sanchez de Miguel, Alejandro, Martinez Delgado, David & Alfaro Navarro, Emilio (2011) Proyecto NixNox disfrutando de los cielos estrellados de Espana. Astronomia (142). pp. 36-42. ISSN 1699-7751, eprints.ucm.es/24185/
  • Zamorano, Jaime, Sanchez de Miguel, Alejandro, Nievas Rosillo, Miguel & Tapia Ayuga, Carlos (2014) NixNox procedure to build Night Sky Brightness maps from SQM photometers observations., eprints.ucm.es/26982/
  • A night sky brightness network with data obtained with fixed SQM photometers of the Spanish Light Pollution Research Network. guaix.fis.ucm.es/splpr/SQM-REECL
Light pollution maps / databases: Useful Light pollution links:
Unihedron supports the goals of the International Dark-Sky Association.

SQM-LE/LU tripod adaptor option


Example

This adaptor kit was designed specifically for the SQM-LE/LU meters and includes a wire guide to hold the cables in place.

The adaptor screws into the back of the SQM-LE or LU 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


SQM-LELU-TA Kit
$15USD

Buy SQM-LE now:
Price $249.99US plus Shipping & Handling.

You may also be interested in; the SQM-LE housing, or our low-cost handheld sky meter (SQM), or our narrow-field handheld sky meter (SQM-L), or our USB connected model (SQM-LU).
Inquire about a turnkey solution with all software packaged on an included netbook.
Compare models.