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(meteorobs) NLC or early twilight?




From latitude 43o56'30" on July 15/16, I observed an extended sky-brightening in 
the east, starting at 2:12 am, extending up 15o at it's highest. It showed no 
details or outstanding features, and did not appear to obscure the sky behind 
it. It was not truly dome-shaped, extending only about 20o in azimuth, but I 
assumed it was most likely twilight at the time, as this was a new and very dark 
location for me, and I was unsure of the start of local astronomical twilight.

However, I've since checked an ephemeris for that location (actually 'xephem'), 
and it lists the beginning of astronomical twilight for that morning as 02:32 
local time. I did NOT note how it changed while true twilight approached, or I 
might have been able to confirm this sighting one way or another.

So what should I assume this was? An NLC sighting at a record low latitude, or 
an indication of just how early twilight can begin in a truly dark Northern sky?

Comments appreciated,
Lew Gramer