gistfile1.as

import calendar
import pytz
import datetime as DT

tz1 = pytz.timezone('US/Eastern')
utc = pytz.timezone('UTC')
now = utc.localize(DT.datetime(2002, 10, 27, 7, 0, 0))
now_tz = now.astimezone(tz1)
now_epoch = calendar.timegm(now_tz.utctimetuple())

begin_day = now_tz.replace(hour=0, minute=0, second=0)
begin_day2 = tz1.normalize(begin_day)

assert begin_day.utctimetuple() == begin_day2.utctimetuple()

begin_epoch = calendar.timegm(begin_day.utctimetuple())
begin_epoch2 = calendar.timegm(begin_day2.utctimetuple())

assert begin_epoch == begin_epoch2