API VERSION: 1.2 API SOURCE: NASA/JPL Horizons API ******************************************************************************* Revised: April 22, 2021 Neptune 899 PHYSICAL DATA (update 2021-May-03): Mass x10^24 (kg) = 102.409 Density (g/cm^3) = 1.638 Equat. radius (1 bar) = 24766+-15 km Volume, 10^10 km^3 = 6254 Vol. mean radius (km) = 24624+-21 Polar radius (km) = 24342+-30 Geometric Albedo = 0.41 Flattening = 0.0171 Sid. rot. period (III)= 16.11+-0.01 hr Sid. rot. rate (rad/s) = 0.000108338 Mean solar day, h =~16.11 h GM (km^3/s^2) = 6835099.97 GM 1-sigma (km^3/s^2) = +-10 Equ. grav, ge (m/s^2) = 11.15 Pol. grav, gp (m/s^2) = 11.41+-0.03 Visual magnitude V(1,0)= -6.87 Vis. mag. (opposition)= +7.84 Obliquity to orbit = 28.32 deg Sidereal orbit period = 164.788501027 y Sidereal orbit period = 60189 d Mean daily motion = 0.006020076dg/d Mean orbit velocity = 5.43 km/s Atmos. temp. (1 bar) = 72+-2 K Escape speed (1 bar) = 23.5 km/s Aroche(ice)/Rp = 2.98 Hill's sphere rad., Rp = 4700 Perihelion Aphelion Mean Solar Constant (W/m^2) 1.54 1.49 1.51 Maximum Planetary IR (W/m^2) 0.52 0.52 0.52 Minimum Planetary IR (W/m^2) 0.52 0.52 0.52 ******************************************************************************* ******************************************************************************* Ephemeris / API_USER Thu Aug 14 15:51:58 2025 Pasadena, USA / Horizons ******************************************************************************* Target body name: Neptune (899) {source: nep097_merged} Center body name: Sun (10) {source: nep097_merged} 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 ******************************************************************************* $$SOE 2460676.500000000 = A.D. 2025-Jan-01 00:00:00.0000 TDB X = 2.987992735576156E+01 Y =-6.341879950443392E-01 Z =-6.754997950415415E-01 VX= 3.941595250081164E-05 VY= 3.160389775728832E-03 VZ=-6.636996572427530E-05 2460676.500694444 = A.D. 2025-Jan-01 00:01:00.0000 TDB X = 2.987992738313355E+01 Y =-6.341858003292957E-01 Z =-6.754998411317725E-01 VX= 3.941539715732043E-05 VY= 3.160389549672231E-03 VZ=-6.636990015457822E-05 $$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 *******************************************************************************