I am trying to create a homemade Sky Quality Meter (SQM) using a TSL2591 light sensor. This sensor measures Illumination (lux), but SQMs measure Luminance (mpsas). I have seen that there are many projects doing something similar, but each one uses a different conversion, which I don't understand.

Is there a way to do this, or to get a good approximation? Note that I am not a physicist, I am a simple developer so all this is new and unknown to me.

Thanks in advance!

Sensor info: https://www.adafruit.com/product/1980

  • 2
    $\begingroup$ Can you explain what “SQM” means? $\endgroup$ Feb 17, 2022 at 10:16
  • 3
    $\begingroup$ @PeterErwin "Sky Quality Meter", a device for measuring sky brightness. See this one for example: link $\endgroup$
    – Boube
    Feb 17, 2022 at 10:37
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    $\begingroup$ @PeterErwin What would go into the design of a simple sky quality meter, used to measure night sky brightness? $\endgroup$
    – uhoh
    Feb 17, 2022 at 22:02
  • 1
    $\begingroup$ I think what you really want is to convert the lux to magnitude, and divide that by the field of view of the sensor, to convert to magnitude per square arcsec. And that's the measure of light pollution which you could convert to a Bortle Scale value. $\endgroup$ Feb 19, 2022 at 6:10


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