Data-Type Definitions (``spacekernel.datamodel``)
-------------------------------------------------


.. data:: SurfCoord_dtype

   **Type:** `numpy.dtype`

   Structured dtype for geodetic surface coordinates on the reference ellipsoid.

   **Fields**:

   - **lat** (float)
     Geodetic latitude :math:`\phi` in radians.
   - **lon** (float)
     Geodetic longitude :math:`\lambda` in radians.

.. data:: LLA_dtype

   **Type:** `numpy.dtype`

   Structured dtype for geodetic coordinates (latitude, longitude, altitude).

   **Fields**:

   - **lat** (float)
     Geodetic latitude :math:`\phi` in radians.
   - **lon** (float)
     Geodetic longitude :math:`\lambda` in radians.
   - **alt** (float)
     Height :math:`h` above the ellipsoid in metres.

.. data:: ENU_dtype

   **Type:** `numpy.dtype`

   Structured dtype for local East–North–Up unit‐vector frames.

   **Fields**:

   - **u_east** (float, shape (3,))
     East unit‐vector components :math:`[x, y, z]`.
   - **u_north** (float, shape (3,))
     North unit‐vector components :math:`[x, y, z]`.
   - **u_up** (float, shape (3,))
     Up (radial) unit‐vector components :math:`[x, y, z]`.

.. data:: AER_dtype

   **Type:** `numpy.dtype`

   Structured dtype for Azimuth–Elevation–Range observations.

   **Fields**:

   - **azimuth** (float)
     Azimuth :math:`\alpha` in radians, measured clockwise from North.
   - **elevation** (float)
     Elevation :math:`\epsilon` in radians above the local horizon.
   - **range** (float)
     Slant range :math:`\rho` in metres.