The book close time in utc.

def utc_book_close_time(self):
        """
        The book close time in utc.
        """
        tz = pytz.timezone(self.timezone)
        close_time = datetime.datetime.strptime(self.close_time, '%H:%M:%S').time()
        close_time = tz.localize(datetime.datetime.combine(datetime.datetime.now(tz), close_time))
        return close_time.astimezone(pytz.utc).time()