17_sgp4_from_tle.cpp

TLE propagation through SGP4 at selected epochs.

// SPDX-License-Identifier: AGPL-3.0-or-later
// Copyright (C) 2026 Vallés Puig, Ramon
 
#include <siderust/sgp4.hpp>
 
#include <iomanip>
#include <iostream>
 
static constexpr const char *L1 =
    "1 00005U 58002B   00179.78495062  .00000023  00000-0  28098-4 0  4753";
static constexpr const char *L2 =
    "2 00005  34.2682 348.7242 1859667 331.7664  19.3264 10.82419157413667";
 
int main() {
  auto tle = siderust::tle::Tle::parse(L1, L2);
  auto prop = siderust::sgp4::Propagator(tle);
 
  std::cout << "Satellite     : NORAD " << tle.norad_id() << '\n';
  std::cout << "Gravity model : " << prop.gravity_model()
            << " (0=WGS-72, 1=WGS-72/IAU, 2=WGS-84)\n";
  std::cout << std::fixed << std::setprecision(10);
  std::cout << "TLE epoch (JD): " << prop.epoch_jd_utc() << "\n\n";
 
  std::cout << std::setw(12) << "t [min]" << "  state\n";
  for (double dt_min : {0.0, 360.0, 720.0, 1080.0}) {
    double jd = prop.epoch_jd_utc() + dt_min / 1440.0;
    auto s = prop.propagate_at(jd);
    std::cout << std::setw(12) << std::setprecision(1) << dt_min << "  " << s << '\n';
  }
 
  return 0;
}