gcrf_to_itrf_astropy
- ssapy.utils.gcrf_to_itrf_astropy(state_vectors, t)[source][source]
Converts position vectors from the GCRF (Geocentric Celestial Reference Frame) to the ITRF (International Terrestrial Reference Frame) using Astropy.
This function is still under development and may not produce 100% accurate results.
Parameters:
- state_vectors (np.array): A 2D array of shape (N, 3), where N is the number of position vectors.
Each row contains the (x, y, z) Cartesian coordinates in meters in the GCRF frame.
t (astropy.time.Time): An Astropy Time object representing the observation time(s) for the transformation.
Returns:
- np.array: A 2D array of shape (N, 3), where N is the number of position vectors. Each row contains
the (x, y, z) Cartesian coordinates in meters in the ITRF frame.
Notes:
The transformation uses Astropy’s SkyCoord and GCRS/ITRS frames for coordinate conversion.
The barycentric position of Earth is calculated using the solar_system_ephemeris context manager with the DE430 ephemeris.
The transformation accounts for Earth’s barycentric position to ensure the coordinates are relative to Earth’s center in the ITRF frame.
The function assumes the input state_vectors are in meters and outputs coordinates in meters.