# Where to find the best values for standard gravitational parameters of solar system bodies?

Where can I find the best values to use for standard gravitational parameters of solar system bodies for numerical simulation experiments?

Here are two sets I've put together. The first set is from Wikipedia, the second set is from the a JPL progress report listing the masses used for the calculation of the DE421 ephemeris.

In addition to the Sun and planets, I've included Earth's Moon, and the three largest asteroids. I am not sure how I should handle the masses of the larger moons of the large planets; I assume they are not counted here and I should deal with them separately.

Is there a significantly better "master table" than the DE430/431 values, or is that about as good as it gets?

NOTE: units are MKS

Wikipedia:        JPL: DE421          JPL: DE430/431
(1) unless         (2) unless            (6) unless
otherwise noted     otherwise noted       otherwise noted
-----------------  --------------------  --------------------
Sun     1.32712440018E+20  1.32712440040944E+20  1.32712440040944E+20
Mercury 2.2032E+13         2.203209E+13          2.203178E+13
Venus   3.24859E+14        3.24858592E+14        3.24858592E+14
Earth   3.986004418E+14    3.98600436233E+14     3.98600435436E+14
Moon    4.9048695E+12      4.902800076E+12       4.902800066E+12
Mars    4.282837E+13       4.2828375214E+13      4.2828375214E+13
Ceres   6.26325E+10        6.2178E+10            6.28093938E+10
Pallas  2.11E+20*G(4,5)    1.3402E+10            1.3923011E+10
Vesta   2.59076E+20*G(3,5) 1.7630E+10            1.7288009E+10
Jupiter 1.26686534E+17     1.267127648E+17       1.267127648E+17
Saturn  3.7931187E+16      3.79405852E+16        3.79405852E+16
Uranus  5.793939E+15       5.7945486E+15         5.7945486E+15
Neptune 6.836529E+15       6.836535E+15          6.83652719958E+15

G = 6.67408E-11 (5)

• Looking at the sources on the Wikipedia page, I see that the Ceres figure is based on Dawn data from 2015, Mars from 2011, while some of the other sources date to 2005, so the data straddles that of DE 421. – Russell Borogove Sep 8 '17 at 14:03
• naif.jpl.nasa.gov/pub/naif/JUNO/kernels/spk/de436s.bsp.lbl but, again, not really different. – user7073 Sep 8 '17 at 15:07
• naif.jpl.nasa.gov/pub/naif/generic_kernels/spk/satellites – user7073 Sep 8 '17 at 15:14
• @uhoh, My apologies for not being clear in my comment, so let me offer two clarifications: 1) Gravitational Parameters and planetary ephemerides are inherently linked, so that they can change for any iteration of DE. I'm not sure if they are estimated every time, but they can be. 2) I didn't mean to imply that DE436 was the latest and greatest. JPL produces DE files specifically for missions at times, and the fact that the file path for the DE436 contains JUNO implies that it was produced for that mission, and not meant for general consumption. DE431 may be the official latest/greatest – DuffBeerBaron Sep 14 '17 at 20:39
• I'll note that my understanding of the generation of the DE kernels is the same as that of @DuffBeerBaron. They are built for specific missions, but they encompass all of the objects known to be useful to that mission, and possibly more. However, these values can be refined over time: the more probe we send out, the more orbital determination solutions we can compute, and therefore the better the resolution of the GM values. I'll also note that DE438 has been released a few weeks ago, for JUNO as well. – ChrisR Jul 21 '18 at 17:19

If you consider the ephemeris files put out by JPL as the final say in terms of simulations, then the data they put in the PKC files alongside the SPK files are the authoritative value, because that's the data used in the simulations.
As a side note, I was looking for the GM value for Nerid, and it's listed on that page, but in the files found on the ftp site along with the SPK files, Nerid's value is set to 0. This suggests that there are discrepancies between the value used in the simulation and what you can find in this table.
• Hi @uhoh, that depends on what/who you consider an authority. Or, in your case "The" authority. If you consider the ephemeris files put out by JPL as the final say in terms of simulations, then the data they put in the pkc files are the authoritative value, because that's the data used in the simulations (naif.jpl.nasa.gov/pub/naif/generic_kernels/pck/gm_de431.tpc) – Kaushik Ghose Jul 22 '18 at 3:17