EPM ephemerides and relativity

Abstract

Abstract. In the seventies of the last century the EPM ephemerides (Ephemerides of Planets and the Moon) of IAA RAS originated and have been developed since that time. These ephemerides are based upon relativistic equations of motion of celestial bodies and light rays and upon relativistic time scales. The updated model of EPM2008 includes the new values of planet masses and other constants, the improved dynamical model with adding Trans-Neptunian Objects and the expanded database . More than 260 parameters have been determined while improving the planetary part of EPM2008 to 550000 observations. EPM2008 have been oriented to ICRF by including into the total solution the VLBI data of spacecraft near the planets. The real uncertainty of EPM ephemerides has been checked by comparison with the JPL's DE ephemerides. Some estimates of the post-model parameters have been obtained: |1 − β| < 0.0002, |1 − γ| < 0.0002,Ġ/G = (−5.9 ± 4.4) · 10 −14 per year, the statistic zero corrections to the planet perihelion advances.Keywords. Relativity, celestial mechanics, ephemerides, radar astronomy Historical introduction: general relativity in EPM ephemeridesIn the seventies of the last century to support space flights the EPM ephemerides (Ephemerides of Planets and the Moon) of IAA RAS originated at about the same time as DE ephemerides and have been developed since that time.After the brilliant explanation by Einstein the strange (43 /cy) discrepancy between theoretical predictions and observations of the secular motion of Mercury perihelion, the planet ephemerides are to be constructed on the basis of General Relativity. The relativistic basis for constructing ephemerides was provided many years ago in the papers by Estabrook (1971, and it has been used for JPL (Standish, 1976), IAA RAS (Krasinsky et al., 1978), and MIT (Ash et al., 1967) ephemerides for more than 30 years. However, for the workers in Russia the main guide was the book of Brumberg (1972). Moreover, the relativistic equations of the planet motion may be given in different coordinate systems of the Schwarzschild metric (parameter α), namely, standard, harmonic, izotropic, etc. However, planet coordinates turned out to be essentially different for the standard and harmonic systems. Brumberg (1979) proved that ephemeris construction and processing of observations should be done in the same coordinate system, in which case the dependence on the coordinate system (parameter α) vanishes. Later on, the resolutions of IAU (1991IAU ( , 2000 recommended to use harmonic coordinates for BCRS. Actually, harmonic coordinates have been used for all modern ephemerides since long ago.Our first ephemerides of the inner planets which were analytical (Krasinsky et al., 1978) in contrast to more perfect analytical ephemerides of the Moon and planets by Chapront and Bretagnon were compared with optical and radar observations. Simultaneously we also computed numerical planet ephemerides. Our comparison revealed that numerical 170 at https://www.cambridge.org/core/terms. https://doi

Gravitational anomalies in the solar system?

“…At present, the orbit determination of the two outermost planets of the Solar system and the dwarf planet Pluto are mostly based on optical observations of relatively modest accuracy, if compared to usual radiometric ones. Thus, no particularly accurate corrections 117,122 ∆̟ have been determined so far, also because the available data records cover barely a full period of Uranus and only parts of the orbits of Neptune and Pluto: indeed, the current accuracies in their ∆̟ are just at the 117,122 " cy…”

“…Such limitations could be over- Table 2. Corrections ∆̟ to the standard secular node precessions of Uranus, Neptune and Pluto, in " cy −1 , phenomenologically determined by contrasting in a least-square sense the dynamical and measurement models of the ephemerides EPM2008 117 to data records spanning almost one century. See Table 1 125 currently en route to the Plutonian system and equipped with advanced transmitting apparatuses to perform accurate radio-science experiments.…”

Updated IAA RAS planetary ephemerides-EPM2011 and their use in scientific research

“…The updated dynamical model of the EPM ephemerides includes Eris (a dwarf planet discovered in 2003, which is more massive than Pluto) and 20 of the largest TNOs into simultaneous integration. The perturbations from the other TNOs were modeled by a homogeneous TNO ring lying in the plane of the ecliptic and having a radius of 43 AU and an estimated mass (Pitjeva, 2010a).…”

Use of MESSENGER radioscience data to improve planetary ephemeris and to test general relativity

“…The previous estimations of these parameters using different techniques and a different data set, can be found in (Bertotti et al 2003;Müller et al 2008;Pitjeva 2009;Williams et al 2009;Manche et al 2010;Konopliv et al 2011;Fienga et al 2011). However, because of Mercury's relatively high eccentricity and its close proximity to the Sun, its orbital motion provides one of the best solar system tests of GR (Anderson et al 1997).…”