//astronomy/io.github.cosinekitty.astronomy/Observer/toStateVector
fun toStateVector(time: Time, equator: EquatorEpoch): StateVector
Calculates geocentric equatorial position and velocity of an observer on the surface of the Earth.
This function calculates position and velocity vectors of an observer on or near the surface of the Earth, expressed in equatorial coordinates. It takes into account the rotation of the Earth at the given time, along with the given latitude, longitude, and elevation of the observer.
The caller may pass a value in equator to select either EquatorEpoch.J2000 for using J2000 coordinates, or EquatorEpoch.OfDate for using coordinates relative to the Earth’s equator at the specified time.
The returned position vector has components expressed in astronomical units (AU). To convert to kilometers, multiply the vector values by the scalar value KM_PER_AU.
The returned velocity vector is measured in AU/day.
The position and velocity of this observer with respect to the Earth’s center.
| time | The date and time for which to calculate the observer’s position vector. |
| equator | Selects the date of the Earth’s equator in which to express the equatorial coordinates. The caller may select EquatorEpoch.J2000 to use the orientation of the Earth’s equator at noon UTC on January 1, 2000, in which case this function corrects for precession and nutation of the Earth as it was at the moment specified by the time parameter. Or the caller may select EquatorEpoch.OfDate to use the Earth’s equator at time as the orientation. |