I know what you mean. It's not uncommon for a suburban nighttime sky to "gain" another ~0.3-to-0.5 magnitude or so around the 2am-3am timeframe. It can occur when some key light sources (perhaps only one or two) in your neighborhood or section of town are extinguished. Fewer lights; darker sky. Some nights it happens; some nights it don't.
I'm sure glad when it does.
Best wishes.
-Dan
I'm sure glad when it does.
Best wishes.
-Dan