def lonlat_to_healpix(self, lon, lat, return_offsets=False):
        """
        Convert longitudes/latitudes to HEALPix indices (optionally with offsets)

        Parameters
        ----------
        lon, lat : :class:`~astropy.units.Quantity`
            The longitude and latitude values as :class:`~astropy.units.Quantity` instances
            with angle units.
        return_offsets : bool
            If `True`, the returned values are the HEALPix pixel as well as
            ``dx`` and ``dy``, the fractional positions inside the pixel. If
            `False` (the default), only the HEALPix pixel is returned.

        Returns
        -------
        healpix_index : `~numpy.ndarray`
            1-D array of HEALPix indices
        dx, dy : `~numpy.ndarray`
            1-D arrays of offsets inside the HEALPix pixel in the range [0:1] (0.5
            is the center of the HEALPix pixels). This is returned if
            ``return_offsets`` is `True`.
        """
        return lonlat_to_healpix(lon, lat, self.nside,
                                 return_offsets=return_offsets, order=self.order)
Convert longitudes/latitudes to HEALPix indices (optionally with offsets)

        Parameters
        ----------
        lon, lat : :class:`~astropy.units.Quantity`
            The longitude and latitude values as :class:`~astropy.units.Quantity` instances
            with angle units.
        return_offsets : bool
            If `True`, the returned values are the HEALPix pixel as well as
            ``dx`` and ``dy``, the fractional positions inside the pixel. If
            `False` (the default), only the HEALPix pixel is returned.

        Returns
        -------
        healpix_index : `~numpy.ndarray`
            1-D array of HEALPix indices
        dx, dy : `~numpy.ndarray`
            1-D arrays of offsets inside the HEALPix pixel in the range [0:1] (0.5
            is the center of the HEALPix pixels). This is returned if
            ``return_offsets`` is `True`.