Quote:
Joeblow wrote:
Just noticed Light Pollution Atlas (link below) recently updated, now providing a 2023 map. Sadly it shows significant increase in LP between 2022 and 2023, in the Sydney region at least. This appears to confirm my own visual observations. I suspect the widespread conversion to LED street lamps played a big part in contributing to that.
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Over the past 6 years, Young Hilltops council has been installing LED lights. If you are in a high density area, these broad spectrum lights can be bad news. In Young, the council has progressively installed LED cutoff down lights and this has resulted in a corresponding decrease from a peak of 39 nW/sq cm to the current value of 31.5 in the Young town centre which is a relatively light polluted Bortle 4 (2015 World Atlas value).
Meanwhile, my property, 30km out of Young has seen no increase since 2012. I do see great variation in transparency throughout the year but have not noted any visible increase in light pollution in the 4.5 years I've lived here. While skies are always dark and has an average Bortle 2 rating by the 2015 World Atlas, my own visual estimates of Bortle value for my skies vary from Bortle 3/4 when pollen, dust, or smoke fill the air, to Bortle 1 on nights of highest transparency. I can see small light domes around my horizon from Young, Cowra, and the Galong mine. There is a broad very faint glow along the east horizon from the Sydney-Newcastle-Wollongong strip about 250km away.
My quick assessment method is to look for the outer arm of the LMC. LMC ~ 7 deg across. If I can see it naked eye, I know the transparency is excellent. A more rigorous assessment of Bortle rating necessitates estimation of limiting magnitude which is always lower for an older observer like me compared to a younger wide eyed observer.
Cheers
Joe