******************************************************************************* Revised: April 12, 2021 Mercury 199 / 1 PHYSICAL DATA (updated 2021-Apr-12): Vol. Mean Radius (km) = 2440+-1 Density (g cm^-3) = 5.427 Mass x10^23 (kg) = 3.302 Volume (x10^10 km^3) = 6.085 Sidereal rot. period = 58.6463 d Sid. rot. rate (rad/s)= 0.00000124001 Mean solar day = 175.9421 d Core radius (km) = ~1600 Geometric Albedo = 0.106 Surface emissivity = 0.77+-0.06 GM (km^3/s^2) = 22031.86855 Equatorial radius, Re = 2440 km GM 1-sigma (km^3/s^2) = Mass ratio (Sun/plnt) = 6023682 Mom. of Inertia = 0.33 Equ. gravity m/s^2 = 3.701 Atmos. pressure (bar) = < 5x10^-15 Max. angular diam. = 11.0" Mean Temperature (K) = 440 Visual mag. V(1,0) = -0.42 Obliquity to orbit[1] = 2.11' +/- 0.1' Hill's sphere rad. Rp = 94.4 Sidereal orb. per. = 0.2408467 y Mean Orbit vel. km/s = 47.362 Sidereal orb. per. = 87.969257 d Escape vel. km/s = 4.435 Perihelion Aphelion Mean Solar Constant (W/m^2) 14462 6278 9126 Maximum Planetary IR (W/m^2) 12700 5500 8000 Minimum Planetary IR (W/m^2) 6 6 6 ******************************************************************************* ******************************************************************************* Ephemeris / WWW_USER Wed Jun 7 14:59:35 2023 Pasadena, USA / Horizons ******************************************************************************* Target body name: Mercury (199) {source: DE441} Center body name: Solar System Barycenter (0) {source: DE441} Center-site name: BODY CENTER ******************************************************************************* Start time : A.D. 2020-Jan-02 00:00:00.0000 TDB Stop time : A.D. 2020-Jan-02 00:01:00.0000 TDB Step-size : 60 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 : (undefined) Output units : KM-D Calendar mode : Mixed Julian/Gregorian Output type : GEOMETRIC cartesian states Output format : 3 (position, velocity, LT, range, range-rate) Reference frame : ICRF ******************************************************************************* JDTDB X Y Z VX VY VZ LT RG RR ******************************************************************************* $$SOE 2458850.500000000 = A.D. 2020-Jan-02 00:00:00.0000 TDB X =-6.706875219569503E+06 Y =-6.044461660946982E+07 Z =-3.175166955207460E+07 VX= 3.346870045424018E+06 VY=-1.701434977841626E+04 VZ=-3.560819216270942E+05 LT= 2.648646033796148E-03 RG= 6.860541065849553E+07 RR=-1.473997213270023E+05 $$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 International Celestial Reference Frame (ICRF) The ICRF is an adopted reference frame whose axes are defined relative to fixed extragalactic radio sources distributed across the sky. The ICRF was aligned with the prior FK5/J2000 dynamical system at the ~0.02 arcsecond level but is not identical and has no associated standard epoch. Symbol meaning [1 day=86400.0 s]: JDTDB Julian Day Number, Barycentric Dynamical Time X X-component of position vector (km) Y Y-component of position vector (km) Z Z-component of position vector (km) VX X-component of velocity vector (km/day) VY Y-component of velocity vector (km/day) VZ Z-component of velocity vector (km/day) LT One-way down-leg Newtonian light-time (day) RG Range; distance from coordinate center (km) RR Range-rate; radial velocity wrt coord. center (km/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/hrzn_batch.txt scripts https://ssd.jpl.nasa.gov/ftp/ssd/SCRIPTS Author : Jon.D.Giorgini@jpl.nasa.gov ******************************************************************************* !$$SOF command = 199 TABLE_TYPE = 'VECTORS' REF_PLANE = 'FRAME' START_TIME = '2020-Jan-02 00:00:00.0000' STOP_TIME = '2020-Jan-02 00:01:00.0000' STEP_SIZE = '1 hours' OUT_UNITS = 'KM-D' CENTER = 500@0