# WGS84: World Geodetic System 1984ΒΆ

The WGS84 ellipsoid as defined by the values given in [Hofmann-WellenhofMoritz2006]:

```>>> from boule import WGS84
>>> print(WGS84)
Ellipsoid(name='WGS84', ...)
>>> # Inverse flattening
>>> print("{:.9f}".format(1 / WGS84.flattening))
298.257223563
>>> # Semimajor axis
>>> print("{:.0f}".format(WGS84.semimajor_axis))
6378137
>>> # Geocentric gravitational constant (GM)
>>> print("{:.9e}".format(WGS84.geocentric_grav_const))
3.986004418e+14
>>> # Angular velocity
>>> print("{:.6e}".format(WGS84.angular_velocity))
7.292115e-05
```

The following are some of the derived attributes:

```>>> print("{:.7f}".format(WGS84.flattening))
0.0033528
>>> print("{:.4f}".format(WGS84.semiminor_axis))
6356752.3142
>>> print("{:.13e}".format(WGS84.linear_eccentricity))
5.2185400842339e+05
>>> print("{:.13e}".format(WGS84.first_eccentricity))
8.1819190842621e-02
>>> print("{:.13e}".format(WGS84.second_eccentricity))
8.2094437949696e-02
>>> print("{:.4f}".format(WGS84.mean_radius))
6371008.7714
>>> print("{:.14f}".format(WGS84.emm))
0.00344978650684
>>> print("{:.10f}".format(WGS84.gravity_equator))
9.7803253359
>>> print("{:.10f}".format(WGS84.gravity_pole))
9.8321849379
```

Note that the ellipsoid gravity at the pole differs from [Hofmann-WellenhofMoritz2006] on the last digit. This is sufficiently small as to not be a cause for concern.