The Life and Times of the Sky Quality Meter (SQM) – Doug Welch – Feb 21, 2022

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Presentation video

RASC Victoria Centre AGM Speaker:  The Life and Times of the Sky Quality Meter (SQM) – Doug Welch, Unihedron

  • 2005 first SQM manufactured
  • Anthony Tekatch
    • co-inventor of SQM
    • PCB design, app coder (Unihedron Device Manager), production of all meters, user support
  • IR limiting filter in front of sensor
  • SQM-L – handheld +- 20º viewing angle
  • SQM-LU – USB connected device, continuous monitor, light pollution surveys with GPS 
  • SQM-L-DL – data logger, runs for about a month on AA batteries
  • SQM-LE – PoE Ethernet device, can function as a cloud monitor
    • Website illustrates the cloud sensing function
  • 10,000 SQM devices being used
  • Used for mapping night sky quality worldwide, with lots of published studies
  • Sea turtle light trespass use case
  • Car-based mobile light pollution surveys – using a SQM-LU & computer
  • Q&A
    • Victoria Centre teams mapped light pollution in our area back in 2010 – Sid Sidhu & David Lee
    • Can interface to Raspberry Pi with Python code
    • Is it weather proof? No, but a weather enclosure is available which copes with most conditions
    • Are the various models interoperable? Yes, all SQMs are calibrated before shipping. 
    • Milky Way can affect readings by 0.2 in southern hemisphere, 0.1 in the northern hemisphere
    • Driving technique – stop then take reading is recommended
    • Magnitudes/square second? It’s a logarithmic surface brightness number. Darkest are 22, meter saturates at 6 (not daytime).
    • Has the SQM been useful in reducing light pollution? Yes, promoting dark areas and encouraging change.
    • Discussion about measuring darkness from a very dark site and the contribution of the Milky Way in that case