*******************************************************************************
 Revised: April 12, 2021             Mercury                            199 / 1

 PHYSICAL DATA (updated 2024-Mar-04):
  Vol. Mean Radius (km) =  2439.4+-0.1    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 = 2440.53 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 / API_USER Fri Oct  9 08:55:23 2026 Pasadena, USA      / Horizons
*******************************************************************************
Target body name: Mercury Barycenter (199)        {source: DE441}
Center body name: Earth (399)                     {source: DE441}
Center-site name: BODY CENTER
*******************************************************************************
Start time      : A.D. 1980-Jan-01 12:00:00.0000 UT 
Stop  time      : A.D. 2025-Jan-01 12:00:00.0000 UT 
Step-size       : DISCRETE TIME-LIST
*******************************************************************************
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    : 6378.137, 6378.137, 6356.752 km {Equator_a, b, pole_c}
Output units    : AU-D
Calendar mode   : Gregorian
Output type     : LT CORRECTED cartesian states
Output format   : 1 (position only)
EOP file        : eop.261008.p270104
EOP coverage    : DATA-BASED 1962-JAN-20 TO 2026-OCT-08. PREDICTS-> 2027-JAN-03
Reference frame : ICRF
*******************************************************************************
            JDUT ,            Calendar Date (UT ),                      X,                      Y,                      Z,
**************************************************************************************************************************
$$SOE
2444240.000000000, A.D. 1980-Jan-01 12:00:00.0000, -2.395317502436015E-02, -1.262722415682342E+00, -5.641970371159546E-01,
2445701.000000000, A.D. 1984-Jan-01 12:00:00.0000,  8.997867964207852E-02, -6.250641422722576E-01, -2.354473328116818E-01,
2447162.000000000, A.D. 1988-Jan-01 12:00:00.0000,  3.834866924496634E-01, -1.220463235029168E+00, -5.839571440195095E-01,
2447893.000000000, A.D. 1990-Jan-01 12:00:00.0000,  3.357709049356417E-01, -6.402092076078461E-01, -2.683355010838880E-01,
2448623.000000000, A.D. 1992-Jan-01 12:00:00.0000, -2.155939768234894E-01, -1.006340135660089E+00, -4.074638891016563E-01,
2450084.000000000, A.D. 1996-Jan-01 12:00:00.0000,  5.068556806534137E-01, -8.034276513119295E-01, -3.740521150344486E-01,
2451545.000000000, A.D. 2000-Jan-01 12:00:00.0000,  4.689544406895053E-02, -1.287983390181064E+00, -5.851951997034279E-01,
2453006.000000000, A.D. 2004-Jan-01 12:00:00.0000, -2.077473000840138E-02, -6.661359280811986E-01, -2.460450498757800E-01,
2454467.000000000, A.D. 2008-Jan-01 12:00:00.0000,  4.444121716208134E-01, -1.165222018202901E+00, -5.609116170640862E-01,
2455198.000000000, A.D. 2010-Jan-01 12:00:00.0000,  2.188875234947023E-01, -6.148359127528472E-01, -2.427953482249915E-01,
2455928.000000000, A.D. 2012-Jan-01 12:00:00.0000, -1.997618840289397E-01, -1.083583419364421E+00, -4.505320106559442E-01,
2456659.000000000, A.D. 2014-Jan-01 12:00:00.0000,  3.144644897836235E-01, -1.261775381935972E+00, -5.983051674734212E-01,
2457389.000000000, A.D. 2016-Jan-01 12:00:00.0000,  4.457314703341527E-01, -7.213132804856779E-01, -3.239704914265897E-01,
2458120.000000000, A.D. 2018-Jan-01 12:00:00.0000, -2.062613360129548E-01, -9.191742166744342E-01, -3.613433092980939E-01,
2458850.000000000, A.D. 2020-Jan-01 12:00:00.0000,  1.226063567849005E-01, -1.298412463502037E+00, -5.987853619696664E-01,
2459216.000000000, A.D. 2021-Jan-01 12:00:00.0000,  4.334182839750004E-01, -1.185879040818135E+00, -5.697835792358446E-01,
2459581.000000000, A.D. 2022-Jan-01 12:00:00.0000,  5.409041243667226E-01, -8.966320357100386E-01, -4.267850551997779E-01,
2459946.000000000, A.D. 2023-Jan-01 12:00:00.0000,  2.901709592456170E-01, -6.291264582269421E-01, -2.582725688401568E-01,
2460311.000000000, A.D. 2024-Jan-01 12:00:00.0000, -1.109834936301077E-01, -7.306056622291343E-01, -2.712809298490489E-01,
2460677.000000000, A.D. 2025-Jan-01 12:00:00.0000, -1.973409878291862E-01, -1.053611674809913E+00, -4.337755495746342E-01,
$$EOE
**************************************************************************************************************************
 
TIME

 Times PRIOR to 1962 are UT1, a mean-solar time closely related to the
prior but now-deprecated GMT. Times AFTER 1962 are in UTC, the current
civil or "wall-clock" atomic time-scale. UTC is kept within 0.9 seconds
of UT1 using integer leap-seconds for 1972 and later years.

  Conversion from the internal Barycentric Dynamical Time (TDB) of solar
system dynamics to the discontinuous civil UT time-scale has not been
determined for UTC times after the next July or January 1st. Therefore,
the last known leap-second is used as a constant over future intervals,
a condition noted here as "UT~".

  Future but as yet undetermined leap-seconds can be expected to change
time-tags in the "UT~" interval and, in general, the UT scale may not be
suitable for purposes that assume time-tag continuity in the ephemeris.
Output in continuous TDB and TT timescales may instead be requested,
though these are not linked to Earth's rotation.

  Time-tags refer to the UT time-scale conversion from TDB on Earth
regardless of observer location within the solar system, although clock
rates may differ due to the local gravity field and no analog to "UT"
may be defined for that location.
 
CALENDAR SYSTEM

  Calendar dates are given in the modern Gregorian system, extended prior to
its 1582-Oct-15 adoption. The Gregorian calendar more closely corresponds to
physical Earth seasons and orbital motion, but can differ by up to 10 days with
historical records made under the prior Julian calendar, more if the Julian
calendar was extended prior to its 45-Jan-1 BC adoption to label the historical
event. Select "mixed" calendar mode if correlation with historical dates prior
to A.D. 1582 is important.

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 au= 149597870.700 km, 1 day= 86400.0 s]:

    JDUT     Julian Day Number, Universal Time
      X      X-component of position vector (au)
      Y      Y-component of position vector (au)
      Z      Z-component of position vector (au)

ABERRATIONS AND CORRECTIONS

 States have been corrected for Newtonian down-leg (receive) light-time
 displacement.

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
    Inquiries   : Jon.D.Giorgini@jpl.nasa.gov
*******************************************************************************
