What Right Ascension and Declinations are observable by a telescope from a particular location?
The declination limit, looking south, is about -52 degrees.  This is basically your latitude minus 90.

At 8pm, due south will be about RA 12hrs, and at 3 am it will be about 19hrs.  The eastern horizon will be about 6 hrs ahead, and that increases as you look further north, until you hit the circumpolar region, when all RAs are visible.