{
  "description": "Mars geocentric apparent ecliptic position at EXACT J2000.0 (JD 2451545.0 TT) — full reduction trace from the Moira engine, with an independent JPL Horizons reference computed for the same instant. This is the raw artifact behind the reduction-trace table on /validation.",
  "generated": "2026-07-10",
  "epoch_note": "J2000.0 is defined as 2000-01-01 12:00:00 TT (Terrestrial Time), which is 2000-01-01 11:58:55.816 UTC (TT-UTC = 64.184 s at this date: 32.184 s TT-TAI + 32 leap seconds). Both queries below use that same UTC instant, so the engine runs at JD_TT = 2451545.0 exactly.",
  "engine": {
    "package": "moira-astro",
    "version": "4.0.0",
    "endpoint": "POST /v1/pipeline/positions/planet",
    "request": { "dt": "2000-01-01T11:58:55.816Z", "body": "Mars", "observer_elev_m": 0 },
    "kernel_pool": ["de441.bsp", "de440.bsp"]
  },
  "epoch": {
    "utc": "2000-01-01T11:58:55.816Z",
    "jd_ut": 2451544.9992571296,
    "jd_tt": 2451545.0,
    "delta_t_seconds": 63.80750000000001,
    "tt_minus_utc_seconds": 64.184,
    "obliquity_deg": 23.437676833843515
  },
  "moira_result": {
    "body": "Mars",
    "frame": "ecliptic of date",
    "center": "geocentric",
    "apparent": true,
    "longitude_deg": 327.96272380577165,
    "latitude_deg": -1.0677882207458393
  },
  "reduction_stages": [
    { "num": 0, "name": "Geometric geocentric", "note": "SSB to body minus SSB to Earth", "delta_arcsec": null, "ref_longitude_deg": 327.974879 },
    { "num": 1, "name": "Light-time iteration", "note": "tau = 0.010683 d; 15.383 min", "delta_arcsec": -15.762352 },
    { "num": 2, "name": "Gravitational deflection", "note": "Sun, Jupiter, Saturn", "delta_arcsec": -0.003057 },
    { "num": 3, "name": "Annual aberration", "note": "Earth barycentric velocity; relativistic", "delta_arcsec": -14.069111 },
    { "num": 4, "name": "IAU 2006 frame bias", "note": "ICRF to dynamical mean J2000", "delta_arcsec": 0.0003 },
    { "num": 5, "name": "IAU 2006 precession", "note": "P03 polynomial; mean equator of date", "delta_arcsec": 0.006469 },
    { "num": 6, "name": "IAU 2000A nutation", "note": "dpsi -13.932010 arcsec; deps -5.769398 arcsec", "delta_arcsec": -13.93201 },
    { "num": 7, "name": "Topocentric parallax", "note": "WGS-84; disabled (geocentric run)", "delta_arcsec": 0.0, "enabled": false }
  ],
  "total_delta_arcsec": -43.759761,
  "reference": {
    "source": "JPL Horizons API",
    "url": "https://ssd.jpl.nasa.gov/api/horizons.api",
    "query": "COMMAND='499', EPHEM_TYPE='OBSERVER', CENTER='500@399', TLIST='2451544.99925713', QUANTITIES='31'",
    "quantity": "31 (ObsEcLon / ObsEcLat, apparent, ecliptic of date)",
    "result": { "ut": "2000-Jan-01 11:58:55.816", "ObsEcLon_deg": 327.9627159, "ObsEcLat_deg": -1.0677844 }
  },
  "residual": {
    "longitude_arcsec": 0.0285,
    "latitude_arcsec": 0.0138,
    "computation": "(moira.longitude_deg - horizons.ObsEcLon_deg) * 3600"
  },
  "reproduce": {
    "moira": "pip install moira-astro==4.0.0 && moira-download-kernels  # then POST the request above to a local moira API, or call Moira().planet_at() directly",
    "horizons": "curl \"https://ssd.jpl.nasa.gov/api/horizons.api?format=text&COMMAND='499'&EPHEM_TYPE='OBSERVER'&CENTER='500@399'&TLIST='2451544.99925713'&QUANTITIES='31'\""
  }
}