Satellitetoolbox Sgp4

SatelliteToolboxSgp4.jl

SGP4/SDP4 orbit propagator for TLE-based prediction. Repo: JuliaSpace/SatelliteToolboxSgp4.jl

Basic Propagation

# One-shot: init + propagate
(r_teme, v_teme, sgp4d) = sgp4(t_min, tle)

# Two-step: init then propagate
sgp4d = sgp4_init(tle)
(r_teme, v_teme) = sgp4!(sgp4d, t_min)       # t_min = minutes from TLE epoch

TLE Fitting

# Fit TLE from osculating state vectors
(fitted_tle, P) = fit_sgp4_tle(vjd, vr_teme, vv_teme;
    estimate_bstar=true, max_iterations=50, atol=1e-4, rtol=1e-4)

# In-place version
(fitted_tle, P) = fit_sgp4_tle!(sgp4d, vjd, vr_teme, vv_teme)

Epoch Update

new_tle = update_sgp4_tle_epoch(tle, new_epoch_jd)

Constants

sgp4c_wgs84       # WGS-84 Float64 (default)
sgp4c_wgs84_f32   # WGS-84 Float32
sgp4c_wgs72       # WGS-72 Float64
sgp4c_wgs72_f32   # WGS-72 Float32

sgp4d = sgp4_init(tle; sgp4c=sgp4c_wgs72)  # Use WGS-72

Key Conventions

• Propagation time in minutes (not seconds!)
• Output: position in km, velocity in km/s
• Output frame: TEME (True Equator, Mean Equinox)
• Returns SVector{3, T}
• In-place ! variants for reduced allocations
• Re-exports SatelliteToolboxBase and SatelliteToolboxTle