Sky Quality Meters (SQM)

SQM

So what exactly is an SQM? SQM stands for sky quality meter. It is an instrument used by astromers and others to measure the luminance of the night sky. It quantifies the skyglow aspect of light pollution and uses units of “magnitudes per square arcsecond.” Technically, it measures the Night Sky Brightness (NSB) at the zenith, in the wavelength range of 390 nm to 600 nm.

Why is this important? As groups like the Blanco County Friends of the Night Sky work to decrease nighttime light pollution, it is helpful to know if we are actually achieving our goals. By taking periodic readings of the night sky luminance, we can quantify our progress (or lack of progress).

SQM Cluster

The Blanco County Friends of the Nigh Sky is the first organization in the country to set up SQM monitoring stations strategically positioned to capture data on night time light pollution for an entire county. We are currently in the process of getting these monitoring sites established. The progress is reflected in the image below. We will update this image from time to time. Once the units are installed, we will begin to feed data collected to Dark Sky Texas and other organizations that monitor night sky pollution. We will update this page from time to time as we progress on this venture.