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Hi §AB & All,
As the crow flies, I live 33km south of Sydney in Engadine. 1.5km either East or West of me is National Park, and to the South there is one small suburb and then very little till you hit Wollongong 50-odd km away.
Mine varies a bit according to humidity and how long it has been since the last southerly change gave the sky a good clean out.
Over the last few months I've been measuring the backyard sky quite a bit with my SQM-L meter and was surprised to find it a little better than I expected.
With the Moon at least 10 degrees below the horizon on all occasions, the worst reading I've got in the last 2 months has been 19.45 which equates to a ZLM of +5.1. The best reading was 20.02 just after midnight about 8 weeks ago which equates to a ZLM of +5.5.
The median reading is around 19.82 which equates to +5.39. By eye, I'd have estimated the average to be about the +5.2 mark.
Where I occasionally observe near Darkes Forest, 20km away South I've taken two readings both at 20.55 equates to a ZLM of +5.85.
At our Southern Highlands site 90km away near Bargo, it is usually between 20.95 and 21.25 equating to ZLMs of +6.1 and +6.24 -- so it can vary a bit too. This site is what I'd call "nearly dark".
The best readings I've had at Mudgee (a true dark site) were 21.95 which equate to +6.61. I've only used the SQM-L there on one trip so far. I reckon I've seen slightly better nights at Mudgee than those tested, so on the best nights the ZLM there is about +6.65 to +6.7.
I've seen better though on the few nights I've spent at Siding Spring Mountain. At significant altitude there it is probably approaching, though not quite +7.0.
Hoping it was of some interest.
Best,
Les D
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