def daylight_utc(self, date, latitude, longitude, observer_elevation=0):
        """Calculate daylight start and end times in the UTC timezone.

        :param date:       Date to calculate for.
        :type date:        :class:`datetime.date`
        :param latitude:   Latitude - Northern latitudes should be positive
        :type latitude:    float
        :param longitude:  Longitude - Eastern longitudes should be positive
        :type longitude:   float
        :param observer_elevation:  Elevation in metres to calculate daylight for
        :type observer_elevation:   int

        :return: A tuple of the UTC date and time at which daylight starts and ends.
        :rtype: (:class:`~datetime.datetime`, :class:`~datetime.datetime`)
        """

        start = self.sunrise_utc(date, latitude, longitude, observer_elevation)
        end = self.sunset_utc(date, latitude, longitude, observer_elevation)

        return start, end
Calculate daylight start and end times in the UTC timezone.

        :param date:       Date to calculate for.
        :type date:        :class:`datetime.date`
        :param latitude:   Latitude - Northern latitudes should be positive
        :type latitude:    float
        :param longitude:  Longitude - Eastern longitudes should be positive
        :type longitude:   float
        :param observer_elevation:  Elevation in metres to calculate daylight for
        :type observer_elevation:   int

        :return: A tuple of the UTC date and time at which daylight starts and ends.
        :rtype: (:class:`~datetime.datetime`, :class:`~datetime.datetime`)