Using OEMEphemeris

Example showing how to construct an OEMEphemeris and access geodetic latitude/longitude and height for each timestamp.

import datetime as dt
import rust_ephem as re

# Create a small OEM ephemeris from the provided test file
begin = dt.datetime(2032, 6, 28, 10, 0, 0, tzinfo=dt.timezone.utc)
end = dt.datetime(2032, 7, 5, 10, 0, 0, tzinfo=dt.timezone.utc)
step_size = 60  # seconds (1-minute resolution)

eph = re.OEMEphemeris(
    oem_path="AXIS27June2032MJ2000_200km_long.oem",
    begin=begin,
    end=end,
    step_size=step_size,
    polar_motion=False,
)

# Interpolated timestamps
print(f"Number of timestamps: {len(eph.timestamp)}")

# Access geodetic arrays derived from ITRS positions
print(f"Latitude (deg) at first timestamp: {eph.latitude_deg[0]}")
print(f"Longitude (deg) at first timestamp: {eph.longitude_deg[0]}")
print(f"Height (m) at first timestamp: {eph.height_m[0]}")

# Use the height (meters) directly instead of computing altitude
# from GCRS vector norm (which includes Earth center offset)
print(f"Height as Quantity: {eph.height[0]}")

# Access GCRS position/velocity
gcrs_pv = eph.gcrs_pv
print("GCRS position (km):", gcrs_pv.position[0])

# Index nearest a particular time
idx = eph.index(dt.datetime(2032, 7, 1, 12, 0, 0, tzinfo=dt.timezone.utc))
print("Index closest to target time:", idx)

# Constraint example: avoid pointing directly at Sun for first timestamp
sun_constraint = re.Constraint.sun_proximity(min_angle=45.0)
satisfied = sun_constraint.in_constraint(
    time=eph.timestamp[idx],
    ephemeris=eph,
    target_ra=180.0,
    target_dec=30.0,
)
print("Constraint satisfied at index?", satisfied)