  
  
Speed of Light 
c = 2.997 924 58 x 10^{8} m s^{−1} 
c 
Status: 
 Natural defining constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.
 A constant fixed by convention.

Notes: 
 The speed of light is an (unchanged) defining value for the IAU
and the IERS. The reference has been updated from CODATA 1998
to CODATA 2006 to reflect the use of the value of this
constant by the current set of CODATA constants.

References: 
 CODATA 2006,
physics.nist.gov/cuu/Constants
 Mohr, P. J. and Taylor, B. N., 2000,
"CODATA recommended values of the fundamental physical constants: 1998,"
Rev. Mod. Phys., 72, pp. 351495.
 Mohr, P. J., Taylor, B. N., and Newell, D. B., 2008,
"The CODATA recommended values of the fundamental physical constants: 2006,"
Rev. Mod. Phys., 80, pp. 633730.

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1−d(TT)/d(TCG) 
L_{G} = 6.969 290 134 x 10^{−10} 
L_{G} 
Status: 
 Auxiliary defining constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.
 A constant fixed by convention

Notes: 
 The value for L_{G} is such that the mean rate of
TT is close to the mean rate of the proper time of an observer located
on the rotating geoid.
 It is specified in IAU 2000 Resolution B1.9 as a defining constant.

References: 
 International Astronomical Union (IAU), 2000,
"Proceedings of the TwentyFourth General Assembly,"
Transactions of the IAU, XXIVB, pp. 3457.
 Petit, G., 2000,
"Report of the BIPM/IAU Joint Committee on relativity for spacetime
reference systems and metrology," in
Proc. of IAU Colloquium 180,
Johnston, K. J., McCarthy, D. D., Luzum, B. J., Kaplan, G. H. (eds.),
U.S. Naval Observatory, Washington, D.C., pp. 275282.

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1−d(TDB)/d(TCB) 
L_{B} = 1.550 519 768 x 10^{−8} 
L_{B} 
Status: 
 Auxiliary defining constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.
 A constant fixed by convention

Notes: 
 L_{B} is specified in
IAU 2006 Resolution B3 as a defining constant.
 The fixed value for L_{B} was derived in 2005 from
the expression
L_{B} =
L_{C} +
L_{G} −
L_{C} x L_{G},
where L_{G} is given in
IAU Resolution B1.9 (2000) and L_{C}
has been determined (Irwin and Fukushima, 1999) using the JPL ephemeris
DE405. When using the DE405, the defining L_{B} value
effectively eliminates a linear drift between TDB and TT, evaluated at
the geocenter.
 When realizing TCB using other ephemerides, the difference between TDB and
TT, evaluated at the geocenter, may include some linear drift, not expected
to exceed 1 ns per year.

References: 
 International Astronomical Union (IAU), 2006
"Proceedings of the TwentySixth General Assembly,"
Transactions of the IAU, XXVIB.
 Irwin, A. and Fukushima, T., 1999,
"A numerical time ephemeris of the Earth,"
Astron. Astrophys., 348, pp. 642652.

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TDB − TCB at T_{0} 
TDB_{0} = −6.55 x 10^{−5} s 
TDB_{0} 
Status: 
 Auxiliary defining constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.
 A constant fixed by convention

Notes: 
 TDB − TCB, the difference between TDB and TCB at
T_{0} (2443144.5003725) is specified in IAU 2006 Resolution B3
as a defining constant.
 TDB = TCB − L_{B} x
(JD_{TCB} − T_{0})
x 86400 + TDB_{0},
where T_{0} = 2443144.5003725.
 The value for TDB_{0} is chosen to provide consistency with the
TDB−TT formula of Fairhead and Bretagnon (1990).

References: 
 International Astronomical Union (IAU), 2006
"Proceedings of the TwentySixth General Assembly,"
Transactions of the IAU, XXVIB.
 Fairhead, L. and Bretagnon, P., 1990,
"An Analytical Formula for the Time Transformation TBTT,"
Astron. Astrophys., 229, pp. 240247.

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Astronomical unit 
au = 1.495 978 707 00 x 10^{11} m 
au 
Status: 
 Auxiliary defining constant.
 Adopted 2012 August 30, IAU GA 2012 Resolution B2
 A constant fixed by convention.

Notes: 
 The IAU GA 2012 Resolution B2
fixes the value of the astronomical unit (au) in kilometres.
The definition states that:
 The astronomical unit is to be used with all time
scales TCB, TDB, TCG, TT, etc.,
 the Gaussian gravitational constant k be deleted from the
system of astronomical constants,
 the value of the solar mass parameter (previously called the
heliocentric gravitational constant), GMS, be determined
observationally in SI units,
 the unique symbol au be used for the astronomical unit.
 This value is the IAU 2009 value adopted 2009 August and it was
taken from Pitjeva and Standish (2009) and is an average of
recent estimates for the au defined by
k.

References: 
 The IAU GA 2012 Resolution B2
 Pitjeva, E.V. and Standish, E.M., 2009,
"Proposals for the masses of the three largest asteroids,
the MoonEarth mass ratio and the astronomical unit,"
Celest. Mech. Dyn. Astr., 103, pp. 365372,
doi: 10.1007/s1056900992038.

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Earth Rotation Angle at J2000.0
Rate of advance of Earth Rotation Angle 
θ_{0} = 0.779 057 273 2640 revolutions
dθ/dUT1 = 1.002 737 811 911 354 48 revolutions UT1day^{−1} 
θ_{0}
dθ/dUT1 
Status: 
 Auxiliary defining constants.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.
 Costants fixed by convention

Notes: 
 These values are specified in
IAU 2000 Resolution B1.8 as defining constants.
 They come from the expression
θ(UT1) = 2π (0.779 057 273 2640 + 1.002 737 811 911 354 48
(Julian UT1 date − 2451545.0))

References: 
 International Astronomical Union (IAU), 2000,
"Proceedings of the TwentyFourth General Assembly,"
Transactions of the IAU, XXIVB, pp. 3457.
 Capitaine, N., Guinot, B., and McCarthy, D.D., 2000,
"Definition of the Celestial Ephemeris Origin and of UT1
in the International Celestial Reference Frame,"
Astron. Astrophys., 355, pp.398405.

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Constant of gravitation 
G = 6.674 28 x 10^{−11}
m^{3}kg^{−1}s^{−2} 
G 
Uncertainty: 
6.7 x 10^{−15}
m^{3}kg^{−1}s^{−2} 
Status: 
 Natural measurable constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 The value for the constant of gravitation, G, has been
changed from the CODATA 1998 value to the value adopted
by CODATA 2006.

References: 
 CODATA 2006,
physics.nist.gov/cuu/Constants
 Mohr, P. J. and Taylor, B. N., 2000,
"CODATA recommended values of the fundamental physical constants: 1998,"
Rev. Mod. Phys., 72, pp. 351495.
 Mohr, P. J., Taylor, B. N., and Newell, D. B., 2008,
"The CODATA recommended values of the fundamental physical constants: 2006,"
Rev. Mod. Phys., 80, pp. 633730.

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Average value of 1−d(TCG)/d(TCB) 
L_{C} = 1.480 826 867 41 x 10^{−8} 
L_{C} 
Uncertainty: 
2 x 10^{−17} 
Status: 
 Other constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 The value for L_{C} is taken from
Irwin and Fukushima (1999) and is the most recent published determination.
It is based on the DE405.
 Before 2006, L_{C} was used to compute
L_{B} but since the adoption of
IAU 2006 Resolution B3, that is no longer true.
 Before IAU 2006, L_{B} was computed as
L_{B} = L_{C} +
L_{G} −
L_{C} × L_{G}.
This relation does not hold [exactly] between the defining values of
L_{B} and
L_{G} and a value of
L_{C} computed from an ephemeris.

References: 
 Irwin, A. and Fukushima, T., 1999,
"A numerical time ephemeris of the Earth,"
Astron. Astrophys., 348, pp. 642652.

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Solar mass parameter 
GM_{S} = 1.327 124 420 99 x 10^{20} m^{3}s^{−2} [TCBcompatible]
GM_{S} = 1.327 124 400 41 x 10^{20} m^{3}s^{−2} [TDBcompatible] 
GM_{S} 
Uncertainty: 
1.0 x 10^{10} m^{3}s^{−2} [TCBcompatible]
1.0 x 10^{10} m^{3}s^{−2} [TDBcompatible]

Status: 
 Body constant.
 2012 August 30, IAU GA 2012 Resolution B2; name and status changed.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 The IAU GA 2012 Resolution B2
defined the astronomical unit (au) as a conventional value, thus breaking
the historical relationship between GM_{S}, k,
and the au. Thus noting (3) and recommends (4) of the resolution
states that GM_{S}, the solar mass parameter, previously
know as the heliocentric gravitational constant be determined
observationally in SI units.
 This value for GM_{S} given is taken from the
Folkner et al. (2008) fit to the DE421 ephemerides. It was not
derived using the value of au, but the
TDBcompatible value of GM_{S} given is consistent with
the value of au given (Pitjeva and Standish,
2009) to within the errors of the estimate.
 The previous definitions
for GM_{S}, k and the au are given in
the archive.

References: 
 Folkner, W.M., Williams, J.G., and Boggs, D.H., 2008,
"The Planetary and Lunar Ephemeris DE 421,"
Memorandum IOM 343R08003, 31 pp.
 Pitjeva, E.V. and Standish, E.M., 2009,
"Proposals for the masses of the three largest asteroids,
the MoonEarth mass ratio and the astronomical unit,"
Celest. Mech. Dyn. Astr., 103, pp. 365372,
doi: 10.1007/s1056900992038.
 The IAU GA 2012 Resolution B2

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Equatorial radius of the Earth 
a_{E} = 6.378 1366 x 10^{6} m [TTcompatible] 
a_{E} 
Uncertainty: 
1 x 10^{−1} m [TTcompatible] 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 a_{E} is taken from Burša, et al. (1998)
and was included in the International Association of Geodesy (IAG)
Special Commission 3 (SC3) Report in Groten (2000).
 The value of a_{E} is the "zero tide" value. See the IERS
Conventions for more explanation of the terminology "zero tide".
 Although the value is listed as TTcompatible, the TCGcompatible value
is equivalent to the number of decimal places listed.

References: 
 Groten, E., 2000,
Geodesists Handbook 2000, Part 4,
www.gfy.ku.dk/~iag/HB2000/part4/groten.htm.
See also
"Parameters of Common Relevance of Astronomy, Geodesy, and Geodynamics,"
J. Geod., 74, pp. 134140.
 Burša, M., Kouba, J., Radej, K., True, S.A., Vatrt, V.,
Vojtišková, M., 1998,
"Mean Earth's Equipotential Surface from Topex/Poseidon Altimetry,"
Studia Geoph. et Geod., 42, pp. 459466,
doi: 10.1023/A:1023356803773.
 IERS Conventions, 2003,
McCarthy, D.D. and Petit, G.,
IERS Technical Note 32.,
Verlag des Bundesamts für Kartographie und Geodäsie,
Frankfurt am Main, 127 pp.

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Dynamical form factor 
J_{2} = 1.082 6359 x 10^{−3} 
J_{2} 
Uncertainty: 
1 x 10^{−10} 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 The dynamical form factor is taken from the
International Association of Geodesy (IAG)
Special Commission 3 (SC3) Report provided by Groten (2000).
 The value for J_{2} is the "zero tide" value
(see IERS Conventions for an explanation of the terminology).
Values according to other conventions can be found in Groten (2000).

References: 
 Groten, E., 2000,
Geodesists Handbook 2000, Part 4,
www.gfy.ku.dk/~iag/HB2000/part4/groten.htm.
See also
"Parameters of Common Relevance of Astronomy, Geodesy, and Geodynamics,"
J. Geod., 74, pp. 134140.
 IERS Conventions, 2003,
McCarthy, D.D. and Petit, G.,
IERS Technical Note 32.,
Verlag des Bundesamts für Kartographie und Geodäsie,
Frankfurt am Main, 127 pp.

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Time rate of change in J_{2} 
dJ_{2}/dt = −3.0 x 10^{−9}
cy^{−1} 
dJ_{2}/dt 
Uncertainty: 
6 x 10^{−10} cy^{−1} 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 The time rate of change in J_{2}
is a value adopted in IAU 2006 Resolution B1 that is consistent
with the adopted IAU 2006 precession model.
 The value is taken from Capitaine et al. (2005).
 A discussion about the uncertainty can be found in
Bourda and Capitaine (2004) and in Hilton et al. (2006)
while a discussion about the components of the
J_{2} variation can be
found in Cheng and Tapley (2004) with a 2008 AGU update (
2008AGUFM.G33A0673C).

References: 
 International Astronomical Union (IAU), 2006,
"Proceedings of the TwentySixth General Assembly,"
Transactions of the IAU, XXVIB.
 Capitaine, N., Wallace, P.T., and Chapront, J., 2005,
"Improvement of the IAU 2000 precession model,"
Astron. Astrophys., 432, pp. 355367.
 Bourda, G. and Capitaine, N., 2004,
"Precession, nutation and space geodetic determination of the
Earth's variable gravity field,"
Astron. Astrophys., 428, pp. 691702.
 Cheng and Tapley, 2004,
"Variations in the Earth's oblateness during the past 28 years,"
Journ. Goephys. Res., 109, B09402,
doi: 10.1029/2004JB003028.
 Hilton, J.L., Capitaine, N., Chapront, J., Ferrandiz, J.M.,
Fienga, A., Fukushima, T., Getino, J., Mathews, P.,
Simon, J.L., Soffel, M., Vondrak, J., Wallace, P.,
and Williams, J., 2006,
"Report of the International Astronomical Union Division I
Working Group on Precession and the Ecliptic,"
Celest. Mech. Dyn. Astr., 94, pp. 351367,
doi: 10.1007/s1056900600012.

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Geocentric gravitational constant 
GM_{E} = 3.986 004 418 x 10^{14} m^{3}s^{−2} [TCBcompatible]
GM_{E} = 3.986 004 415 x 10^{14} m^{3}s^{−2} [TTcompatible]
GM_{E} = 3.986 004 356 x 10^{14} m^{3}s^{−2} [TDBcompatible] 
GM_{E} 
Uncertainty: 
8 x 10^{5} m^{3}s^{−2} [TCBcompatible]
8 x 10^{5} m^{3}s^{−2} [TTcompatible]
8 x 10^{5} m^{3}s^{−2} [TDBcompatible] 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

References: 
 Ries, J. C., Eanes, R. J., Shum, C. K., and Watkins, M. M., 1992,
"Progress in the Determination of the Gravitational Coefficient
of the Earth,"
Geophys. Res. Lett., 19(6), pp. 529531.

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Potential of the geoid 
W_{0} = 6.263 685 60 x 10^{7}
m^{2}s^{−2} 
W_{0} 
Uncertainty: 
5 x 10^{−1} m^{2}s^{−2} 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

References: 
 Groten, E., 2000,
Geodesists Handbook 2000, Part 4,
www.gfy.ku.dk/~iag/HB2000/part4/groten.htm.
See also
"Parameters of Common Relevance of Astronomy, Geodesy, and Geodynamics,"
J. Geod., 74, pp. 134140.

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Nominal mean angular velocity of the Earth 
ω = 7.292 115 x 10^{−5}
rad s^{−1} [TTcompatible] 
ω 
Uncertainty: 
(see Notes) 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 ω is a nominal value and was chosen to have the number
of significant digits limited to those for which the value can be
considered constant.
 Although the value is listed as TTcompatible, the TCGcompatible
value is equivalent to the number of decimal places listed.

References: 
 Groten, E., 2000,
Geodesists Handbook 2000, Part 4,
www.gfy.ku.dk/~iag/HB2000/part4/groten.htm.
See also
"Parameters of Common Relevance of Astronomy, Geodesy, and Geodynamics,"
J. Geod., 74, pp. 134140.

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Ratio mass of the Moon to the Earth 
M_{M}/M_{E}
= 1.230 003 71 x 10^{−2} 
M_{M}/M_{E} 
Uncertainty: 
4 x 10^{−10} 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 This value is equivalent to M_{E} / M_{M}
= 81.300 5678 ± 2.7 × 10^{6}.

References: 
 Pitjeva, E.V. and Standish, E.M., 2009,
"Proposals for the masses of the three largest asteroids,
the MoonEarth mass ratio and the astronomical unit,"
Celest. Mech. Dyn. Astr., 103, pp. 365372,
doi: 10.1007/s1056900992038.

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Ratio of the mass of the Sun to Mercury 
M_{S}/M_{Me} = 6.023657330 x 10^{6} 
M_{S}/M_{Me} 
Uncertainty: 
2.35 x 10^{−1} 
Status: 
 Body constant.
 Adopted CBE 2015 May 25.

References: 
 Mazarico, E., Genova, A., Goossens, S., Lemoine, F.G., Neumann, G.A.,
Zuber, M.T., Smith, D.E., Solomon, S.C., 2014,
"The gravity field, orientatation, and ephemeris of Mercury from
MESSENGER observations after three years in orbit,"
J. Geophys. Res.: Planets, 119, pp. 337349,
doi:10.1002/2014JE004675.

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Ratio of the mass of the Sun to Venus 
M_{S}/M_{Ve} = 4.085 237 19 x 10^{5} 
M_{S}/M_{Ve} 
Uncertainty: 
8 x 10^{−3} 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

References: 
 Konopliv, A.S., Banerdt, W.B., and Sjogren, W.L., 1999,
"Venus Gravity: 180th Degree and Order Model,"
Icarus, 139, pp. 318.

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Ratio of the mass of the Sun to Mars 
M_{S}/M_{Ma} = 3.098 703 59 x 10^{6} 
M_{S}/M_{Ma} 
Uncertainty: 
2 x 10^{−2} 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 Includes the sum of the masses of the body and its satellites.

References: 
 Konopliv, A.S., Yoder, C.F., Standish, E.M., Yuan, D.N.,
Sjogren, W.L., 2006,
"A global solution for the Mars static and seasonal gravity, Mars
orientation, Phobos and Deimos masses, and Mars ephemeris,"
Icarus, 182(1), pp. 2350.

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Ratio of the mass of the Sun to Jupiter 
M_{S}/M_{J} = 1.047 348 644 x 10^{3} 
M_{S}/M_{J} 
Uncertainty: 
1.7 x 10^{−5} 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 Includes the sum of the masses of the body and its satellites.

References: 
 Jacobson, R.A., Haw, R.J., McElrath, T.P., and Antreasian, P.G., 2000,
"A Comprehensive Orbit Reconstruction for the Galileo Prime Mission in
the J2000 System,"
J. Astronaut. Sci., 48(4), pp. 495516.

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Ratio of the mass of the Sun to Saturn 
M_{S}/M_{Sa} = 3.497 9018 x 10^{3} 
M_{S}/M_{Sa} 
Uncertainty: 
1 x 10^{−4} 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 Includes the sum of the masses of the body and its satellites.

References: 
 Jacobson, R.A., Antreasian, P.G., Bordi, J.J., Criddle, K.E.,
Ionasescu, R., Jones, J.B., Mackenzie, R.A., Pelletier, F.J.,
Owen Jr., W.M., Roth, D.C. and Stauch, J.R., 2006,
"The gravity field of the Saturnian system from satellite
observations and spacecraft tracking data,"
Astron. J., 132(6), pp. 25202526.

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Ratio of the mass of the Sun to Uranus 
M_{S}/M_{U} = 2.290 295 1 x 10^{4} 
M_{S}/M_{U} 
Uncertainty: 
1.7 x 10^{−2} 
Status: 
 Body constant.
 Adopted CBE 2015 May 25.

Notes: 
 Includes the sum of the masses of the body and its satellites.

References: 
 Jacobson, R.A., 2014,
"The orbits of the Uranian satellites and rings, the gravity field
of the Uranian system, and the orientation of the pole of Uranus,"
Astron. J., 148:76, 13 pp,
doi:10.1088/00046256/148/5/76.

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Ratio of the mass of the Sun to Neptune 
M_{S}/M_{N} = 1.941 226 x 10^{4} 
M_{S}/M_{N} 
Uncertainty: 
3 x 10^{−2} 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 Includes the sum of the masses of the body and its satellites.

References: 
 Jacobson, R.A., 2009,
"The Orbits of the Neptunian Satellites and the Orientation of the
Pole of Neptune,"
Astron. J., 137, pp. 43224329,
doi: 10.1088/0046256/137/5/4322.

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Ratio of the mass of the Sun to (134340) Pluto 
M_{S}/M_{P} = 1.360 5 x 10^{8} 
M_{S}/M_{P} 
Uncertainty: 
2.1 x 10^{5} 
Status: 
 Body constant.
 Adopted CBE 2015 May 25.

Notes: 
 Includes the sum of the masses of the body and its satellites.

References: 
 Brozović, M., Showalter, M.R., Jacobson, R.A., and Buie, M.W., 2015,
"The orbits and masses of satellites of Pluto,"
Icarus, 246, pp. 317329.

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Ratio of the mass of the Sun to (136199) Eris 
M_{S}/M_{Eris} = 1.191 x 10^{8} 
M_{S}/M_{Eris} 
Uncertainty: 
1.4 x 10^{6} 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 Includes the sum of the masses of the body and its satellites.
 Equivalently M_{Eris}/M_{S}
= 8.396 x 10^{−9} ± 0.100 x 10^{−9}.

References: 
 Brown, M.E. and Schaller, E.L., 2007,
"The mass of Dwarf Planet Eris," Science, 316, p. 1585,
doi: 10.1126/science.1139415.

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Ratio of the mass of (1) Ceres to the Sun 
M_{Ceres}/M_{S} = 4.72 x 10^{−10} 
M_{Ceres}/M_{S} 
Uncertainty: 
3 x 10^{−12} 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

References: 
 Pitjeva, E.V. and Standish, E.M., 2009,
"Proposals for the masses of the three largest asteroids,
the MoonEarth mass ratio and the astronomical unit,"
Celest. Mech. Dyn. Astr., 103, pp. 365372,
doi: 10.1007/s1056900992038.

  Top 
  
Ratio of the mass of (2) Pallas to the Sun 
M_{Pallas}/M_{S} = 1.03 x 10^{−10} 
M_{Pallas}/M_{S} 
Uncertainty: 
3 x 10^{−12} 
Status: 
 Body constant.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

References: 
 Pitjeva, E.V. and Standish, E.M., 2009,
"Proposals for the masses of the three largest asteroids,
the MoonEarth mass ratio and the astronomical unit,"
Celest. Mech. Dyn. Astr., 103, pp. 365372,
doi: 10.1007/s1056900992038.

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Ratio of the mass of (4) Vesta to the Sun 
M_{Vesta}/M_{S} = 1.302 684 6 x 10^{−10} 
M_{Vesta}/M_{S} 
Uncertainty: 
9 x 10^{−17} 
Status: 
 Body constant.
 Adopted CBE 2015 May 25.

References: 
 Konopliv, A.S., Asmar, S.W., Park, R.S., Bills, B.G., Centinello, F.,
Chamberlin, A.B., Ermakov, A., Gaskell, R.W., Rambaux, N., Raymond, C.A.,
Russell. C.T., Smith, D.E., Tricarico, P., Zuber, M.T., 2014,
"The Vesta gravity field, spin pole and rotatin period, landmark positions,
and ephemeris from the Dawn tracking and optical data,"
Icarus, 240, pp. 103117,

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Obliquity of the ecliptic at J2000.0 
ε_{J2000} = 8.438 1406 x 10^{4} " 
ε_{J2000} 
Uncertainty: 
1 x 10^{−3} " 
Status: 
 Initial value at J2000.0.
 IAU 2009 adopted constant.
 Adopted CBE 2009 August 10.

Notes: 
 The obliquity of the ecliptic at J2000.0 is from the
Hilton et al. (2006) report from the IAU Working Group
on precession and the ecliptic. This value is taken from the
P03 precession model of Capitaine et al. (2003) and
was adopted in IAU 2006 Resolution B1.
 The value was determined by Chapront et al. (2002) using
lunar laser ranging observations.
 ε_{J2000} is a component of the IAU 2006
precession model that includes expressions that are time
dependent.

References: 
 International Astronomical Union (IAU), 2006
"Proceedings of the TwentySixth General Assembly",
Transactions of the IAU, XXVIB.
 Hilton, J.L., Capitaine, N., Chapront, J., Ferrandiz, J.M.,
Fienga, A., Fukushima, T., Getino, J., Mathews, P., Simon, J.L.,
Soffel, M., Vondrak, J., Wallace, P., and Williams, J., 2006,
"Report of the International Astronomical Union Division I Working Group
on Precession and the Ecliptic,"
Celest. Mech. Dyn. Astr., 94, pp. 351367,
doi: 10.1007/s1056900600012.
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