API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: Jun 02, 2025 Phobos / (Mars) 401 SATELLITE PHYSICAL PROPERTIES: Radius (km) = 13.1 x11.1 x9.3 Density (g cm^-3) = 1.90 +- 0.08 Mass (10^20 kg ) = 1.08 (10^-4) Geometric Albedo = 0.06 (+- 0.1) V(1,0) = +11.8 SATELLITE ORBITAL DATA: Semi-major axis, a (km) = 9.3772(10^3) Orbital period = 0.319 d Eccentricity, e = 0.0151 Rotational period = Synchronous Inclination, i (deg) = 1.082 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Thu Aug 14 16:19:27 2025 Pasadena, USA / Horizons ******************************************************************************* Target body name: Phobos (401) {source: mar099} Center body name: Sun (10) {source: DE441} Center-site name: BODY CENTER ******************************************************************************* Start time : A.D. 2025-Jan-01 00:00:00.0000 TDB Stop time : A.D. 2025-Jan-01 00:01:00.0000 TDB Step-size : 1 minutes ******************************************************************************* Center geodetic : 0.0, 0.0, 0.0 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 0.0, 0.0, 0.0 {E-lon(deg),Dxy(km),Dz(km)} Center radii : 695700.0, 695700.0, 695700.0 km {Equator_a, b, pole_c} Output units : AU-D Calendar mode : Mixed Julian/Gregorian Output type : GEOMETRIC cartesian states Output format : 2 (position and velocity) Reference frame : Ecliptic of J2000.0 ******************************************************************************* JDTDB X Y Z VX VY VZ ******************************************************************************* $$SOE 2460676.500000000 = A.D. 2025-Jan-01 00:00:00.0000 TDB X =-5.216607506283159E-01 Y = 1.525290094552813E+00 Z = 4.474552444674667E-02 VX=-1.371531677510715E-02 VY=-2.797359927923991E-03 VZ= 7.604209362929195E-04 2460676.500694444 = A.D. 2025-Jan-01 00:01:00.0000 TDB X =-5.216702775783473E-01 Y = 1.525288146474805E+00 Z = 4.474605348954465E-02 VX=-1.372226672058481E-02 VY=-2.813122639161171E-03 VZ= 7.632054629505637E-04 $$EOE ******************************************************************************* TIME Barycentric Dynamical Time ("TDB" or T_eph) output was requested. This continuous coordinate time is equivalent to the relativistic proper time of a clock at rest in a reference frame co-moving with the solar system barycenter but outside the system's gravity well. It is the independent variable in the solar system relativistic equations of motion. TDB runs at a uniform rate of one SI second per second and is independent of irregularities in Earth's rotation. CALENDAR SYSTEM Mixed calendar mode was active such that calendar dates after AD 1582-Oct-15 (if any) are in the modern Gregorian system. Dates prior to 1582-Oct-5 (if any) are in the Julian calendar system, which is automatically extended for dates prior to its adoption on 45-Jan-1 BC. The Julian calendar is useful for matching historical dates. The Gregorian calendar more accurately corresponds to the Earth's orbital motion and seasons. A "Gregorian-only" calendar mode is available if such physical events are the primary interest. REFERENCE FRAME AND COORDINATES Ecliptic at the standard reference epoch Reference epoch: J2000.0 X-Y plane: adopted Earth orbital plane at the reference epoch Note: IAU76 obliquity of 84381.448 arcseconds wrt ICRF X-Y plane X-axis : ICRF Z-axis : perpendicular to the X-Y plane in the directional (+ or -) sense of Earth's north pole at the reference epoch. Symbol meaning [1 au= 149597870.700 km, 1 day= 86400.0 s]: JDTDB Julian Day Number, Barycentric Dynamical Time X X-component of position vector (au) Y Y-component of position vector (au) Z Z-component of position vector (au) VX X-component of velocity vector (au/day) VY Y-component of velocity vector (au/day) VZ Z-component of velocity vector (au/day) ABERRATIONS AND CORRECTIONS Geometric state vectors have NO corrections or aberrations applied. Computations by ... Solar System Dynamics Group, Horizons On-Line Ephemeris System 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA General site: https://ssd.jpl.nasa.gov/ Mailing list: https://ssd.jpl.nasa.gov/email_list.html System news : https://ssd.jpl.nasa.gov/horizons/news.html User Guide : https://ssd.jpl.nasa.gov/horizons/manual.html Connect : browser https://ssd.jpl.nasa.gov/horizons/app.html#/x API https://ssd-api.jpl.nasa.gov/doc/horizons.html command-line telnet ssd.jpl.nasa.gov 6775 e-mail/batch https://ssd.jpl.nasa.gov/ftp/ssd/horizons_batch.txt scripts https://ssd.jpl.nasa.gov/ftp/ssd/SCRIPTS Author : Jon.D.Giorgini@jpl.nasa.gov *******************************************************************************