Quote:
Originally Posted by mithrandir
[T]he darkest you could possibly get (other down a mine with the lights off) would be a new moon night, far from town, under total cloud. The limit for SQMs is supposed to be about 22.
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Hi. At a truly dark site during new moon you'll approach 22*, so long as you aim the SQM at a "dark" part of the sky, but under overcast skies you'll easily exceed 22.
On Unihedron's site there are readings in the 23+ range from places such as Cherry Springs. Those were taken under heavy cloud cover. Had it been clear the readings would have been much reduced, probably around upper 20 to 21ish.
*Reading from my dark mountain site have slightly exceeded 22, but I remain unconvinced, although it's been claimed that SQMs in deepest darkest Namibia and the Aussie outback have also handily beat the 22 limit. Anthony Trekatch at Unihedron told me that he suspects low 22 readings (eg 22.0 to 22.05) from such sites
may be accurate.