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Old 22-02-2012, 03:48 PM
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lepton3 (Ivan)
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Join Date: Jan 2007
Location: Adelaide, Australia
Posts: 670
I'm not sure if it is possible to have any reasonable seeing after about 12 am local time from here in the NE suburbs of Adelaide during summer.

I've done a lot of nights of long duration photometry, from twilight to twilight, and the trend is always for the FWHM to improve a bit from about 9pm to 11pm, then deteriorate steadily from there until dawn. I don't know, possibly it is something to do with the difference between the ground temperature and air temperature in a built up area. The one or two occasions where the seeing has been OK in the morning has been when the previous day was unusually cool.

Things seemed a lot more stable in winter, just that there were fewer clear nights (but actually I think this summer has been cloudier than the last).

-Ivan
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