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San Jose, CA has/had low pressure sodium lights to reduce light pollution for the benefit of Lick Observatory on Mt. Hamilton since at least the early 1980's.
by 1letterunixname 3y ago
San Jose, CA has/had low pressure sodium lights to reduce light pollution for the benefit of Lick Observatory on Mt. Hamilton since at least the early 1980's.
https://en.wikipedia.org/wiki/Lick_Observatory https://en.wikipedia.org/wiki/Lick_Observatory
- KennyBlanken 3y agoIt's not to reduce light pollution, it's to have all the light pollution be in an exceptionally narrow band that the observatory can then filter out. The reason LED lights are so terrible for astronomers is because although they require much less light to achieve the same visibility, the spectrum is very spread out across multiple peaks, with different manufacturers having different peaks.
- perilunar 3y agoSingle color LEDs are also monochromatic. If they ever need to replace the low pressure sodium lights they could switch to yellow or orange LEDs.