astronomy/generate/lagrange/check_L4.txt

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 Revised: Jul 11, 2019                 EM-L4                               3014
                              (Earth-Moon Lagrange 4)

  #1) The Earth-Moon Lagrange-4 point (EM-L4) is a location where the Moon's 
       gravitational field partially counters that of the Earth. EM-L4 is one 
       of the stable "Trojan" points (along with EM-L5). Small perturbations 
       can displace an object from EM-L4, but it can return to the stable 
       point.

  #2) EM-L4 lies 60 degrees ahead of the Earth-Moon system along the Moon's 
       orbit in plane of the orbit. It is about 1 lunar distance from the 
       Earth and from the Moon (straight-lines), so 356000 to 407000 km,
       averaging 385000 km from Earth and Moon centers, forming the apex of
       an equilateral triangle, with the Earth and Moon defining the base-line.

 Time-span available: 1900-Jan-01 to 2151-Jan-01
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Ephemeris / WWW_USER Thu Feb 17 18:31:54 2022 Pasadena, USA      / Horizons
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Target body name: EM-L4 (3014)                    {source: Earth-Moon_L4}
Center body name: Earth (399)                     {source: DE441}
Center-site name: BODY CENTER
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Start time      : A.D. 2020-Mar-24 06:00:00.0000 TDB
Stop  time      : A.D. 2020-Mar-25 06:00:00.0000 TDB
Step-size       : 1440 minutes
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Center geodetic : 0.00000000,0.00000000,0.0000000 {E-lon(deg),Lat(deg),Alt(km)}
Center cylindric: 0.00000000,0.00000000,0.0000000 {E-lon(deg),Dxy(km),Dz(km)}
Center radii    : 6378.1 x 6378.1 x 6356.8 km     {Equator, meridian, pole}    
Output units    : AU-D
Output type     : GEOMETRIC cartesian states
Output format   : 2 (position and velocity)
EOP file        : eop.220216.p220512
EOP coverage    : DATA-BASED 1962-JAN-20 TO 2022-FEB-16. PREDICTS-> 2022-MAY-11
Reference frame : ICRF
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JDTDB
   X     Y     Z
   VX    VY    VZ
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$$SOE
2458932.750000000 = A.D. 2020-Mar-24 06:00:00.0000 TDB 
 X = 1.262170577138596E-03 Y = 2.254660738885763E-03 Z = 8.439158665950467E-04
 VX=-4.935321457947509E-04 VY= 2.245912867279576E-04 VZ= 1.436629421560135E-04
2458933.750000000 = A.D. 2020-Mar-25 06:00:00.0000 TDB 
 X = 7.445211227239128E-04 Y = 2.427928910875577E-03 Z = 9.679787398326978E-04
 VX=-5.378861860962063E-04 VY= 1.206328432960384E-04 VZ= 1.035202699747598E-04
$$EOE
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TIME

  Barycentric Dynamical Time ("TDB" or T_eph) output was requested. This
continuous relativistic coordinate time is equivalent to the relativistic
proper time of a clock at rest in a reference frame comoving 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 dates prior to 1582-Oct-15 are in the Julian calendar system.
Later calendar dates are in the Gregorian system.

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]:

    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/hrzn_batch.txt
                  scripts        https://ssd.jpl.nasa.gov/ftp/ssd/SCRIPTS
    Author      : Jon.D.Giorgini@jpl.nasa.gov
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