Quantifying Darkness Overhead

squims-cb_1242.jpgAstroCampers have been monitoring the quality of the night sky since 2006.  In 2016 the practice continued.  

On Sunday night, July 3, under clear skies, counselor Chuck Bueter used Sky Quality Meters (#133 and #9896) and the Dark Sky Meter app to get values of 21.07, 21.18, and 20.48 magnitudes per square arcseconds (dubbed "squirms", respectively.

squims-kids_1515.jpgTwo night later, the AstroCampers got average values of 20.91, 21.03, and 20.43.  

Using just the SQMs to maintain continuity with past years, we average the four SQM values to get a value of 21.05 magnitudes per square arcsecond.

The scale for measuring brightness is logarithmic, and the value at AstroCamp is impressive.  For comparison, an urban sky may be about 17 squims, whereas an ideal sky approaches 22 squims.  


Light pollution impacts the quality of the night sky.  You can lessen your impact on the beauty of the night by installing and using them only where necessary.  When choosing outdoor lighting, incorporate these three tenets:

1.  All outdoor lighting shall be full cutoff, or fully shielded.

2.  If LED lights are used, they shall have a correlated color temperature (CCT) less than 3000K.

3.  All lights shall minimize glare, sky glow, and light trespass.


Thanks for proactively acting to preserve the night sky and the splendor within it.


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