LATLONtoGCRF {asteRisk} | R Documentation |
Convert coordinates from geodetic latitude, longitude and altitude to GCRF
Description
The GCRF (Geocentric Celestial Reference Frame) frame of reference is an Earth-centered inertial coordinate frame, where the origin is also placed at the center of mass of Earth and the coordinate frame is fixed with respect to the stars (and therefore not fixed with respect to the Earth surface in its rotation). The X-axis is aligned with the mean equinox of Earth at 12:00 Terrestrial Time on the 1st of January, 2000, and the Z-axis is aligned with the Earth´s rotation axis. This function converts geodetic latitude, longitude and altitude to Cartesian coordinates in the GCRF frame. The WGS84 Earth ellipsoid model is used.
Usage
LATLONtoGCRF(position_LATLON, dateTime, degreesInput=TRUE)
Arguments
position_LATLON |
Vector with the latitude, longitude and altitude of the object. Latitude and longitude can be provided in sexagesimal degrees or in radians (by default, sexagesimal degrees are asumed). Altitude must be provided in meters. |
dateTime |
Date-time string with the date and time in UTC corresponding to the provided geodetic coordinates. |
degreesInput |
Logical indicating if the input latitude and longitude are
in sexagesimal degrees. If |
Value
A vector with three elements, corresponding to the X, Y and Z components of position in meters in the ECEF frame, in this order.
References
https://apps.dtic.mil/sti/pdfs/ADA280358.pdf
Examples
if(requireNamespace("asteRiskData", quietly = TRUE)) {
latitude <- 37.3891
longitude <- -5.9845
altitude <- 20000
# Let´s calculate the corresponding coordinates in GCRF frame, assuming that
# the provided coordinates were valid the 20th of October, 2020 at 15:00:00 UTC
coordinatesGCRF <- LATLONtoGCRF(c(latitude, longitude, altitude),
dateTime="2020-10-20 15:00:00")
}