A Sky Quality Measurement of 20.92 is a very high value (and unfortunately exceptional).
SQM Measurement the night of 6 to 7 November 2024, with a maximal SQM of 20.94
The meteo conditions: a high pressure high over Western Europe, with mist. It was not a clear sky however, it was simply dark because of the dense mist. The blue graph indicate sthe sky temperature (IR measured), this needs to be way negative for a clear sky.
Also remarkable is the jump in SQM at the moments the public lighting switches off and on. The sky dims with a full unit of SQM. Despite the better LED fixtures, there is still a large impact of the public street lights.
A big change as last week, the old lights were replaced with LED.
It’s very frustrating that this happened without any questions or communication. It’s even my impression that the municipality Hoegaarden does not even know about it. It seems that Fluvius is doing this all in silence.
So an opportunity was missed, to get decent light fixtures. It´s not all bad. Tjoyfhbthey seem brighter, the light color is more yellow. Also they project their light not as far in the gardens as the old fixtures.
The overall light pollution sideways and upwards seems to be improved; Below two pictures from the all-sky camera that give an impression.
Old situation with Metal-Halide lamps HID, resulting in two big intrusions, the light at left is 37 meters from the camera, and a few meters below it. For the source at the right, it’s 39 meters. There is a third light at only 20 meters to the NNW but it is shielded by my house. You can see it lighting our neighbour’s house to the N. A picture in similar conditions with the NEW streetlights. Only the light in the ENE is directly visible, the light intrusion is a lot less. Also the house to the North is not illuminated anymore.
What’s the impact on SQM? with a clear sky and humidity around 80%, there is still a jump on SQM after midnight – when the lights go out. The SQM measurement jumps from 20.05 to 20.30 which is considerable (SQM is a logarithmic scale).
A gif displaying the image a few minutes before, and the image a few minutes after midnight. Despite the new LED fixtures it’s clear that there is still a large impact of light pollution.
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