A new set of 13 asteroid ephemerides files in XEPH format is now available on our distribution server. The new files cover the time span from 2019-11-30 to 2025-05-23 and include the first 640,000 numbered asteroids. These XEPH files can be used to compute high-precision ephemerides with our solar system ephemerides engine, as well as to generate asteroid annotations for plate-solved images with our standard AnnotateImage script.
The new XEPH files provide Chebyshev polynomial expansions for position in barycentric rectangular coordinates coherent with fundamental JPL planetary and lunar DE440 ephemerides (ICRS), with maximum truncation errors below 1e–10 au (about 15 meters) for the vast majority of objects in the main asteroid belt, and proportionally smaller errors for objects closer to the Sun.
These XEPH files have been generated by numerical integration of perturbed orbital motion with our standard EphemerisGenerator process. Initial conditions have been obtained from JPL Small–Body Element databases, latest ELEMENTS.NUMBR file for epoch 2023-09-13. The implemented physical model includes the following:
Acceleration terms due to oblateness (zonal harmonics J2) have not been included in this release since their contribution is negligible to the accuracy of computed positional ephemerides for the set of objects in this numerical integration.
Please note that these files don't include the 343 most massive asteroids and the 30 largest Kuiper belt objects, which are already available directly on the PixInsight platform for a much larger time span (from 1550 to 2650) from DE440 ephemerides. So, if you are going to generate asteroid annotations, remember to include an Asteroids annotation layer besides custom XEPH layers.
The entire numerical integration executed to generate these 13 XEPH files (1.7 GiB) has required 15.5 hours on our new MARS-1 server: GIGABYTE R263-Z33 (rev. AAF1) server with an AMD EPYC 9654 96-core processor and 768 GiB of RAM running Kubuntu 22.04 LTS Linux. The integration has been performed by four simultaneous instances of the PixInsight core application, each limited to 40 processor cores.
We hope you enjoy this new release.
The new XEPH files provide Chebyshev polynomial expansions for position in barycentric rectangular coordinates coherent with fundamental JPL planetary and lunar DE440 ephemerides (ICRS), with maximum truncation errors below 1e–10 au (about 15 meters) for the vast majority of objects in the main asteroid belt, and proportionally smaller errors for objects closer to the Sun.
These XEPH files have been generated by numerical integration of perturbed orbital motion with our standard EphemerisGenerator process. Initial conditions have been obtained from JPL Small–Body Element databases, latest ELEMENTS.NUMBR file for epoch 2023-09-13. The implemented physical model includes the following:
- Perturbations from Mercury, Venus, Earth, Moon, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. State vectors and constants are provided by XEPH fundamental ephemerides (currently JPL DE440).
- Perturbations from the 343 most massive asteroids used in DE440 numerical integrations. State vectors and constants are provided by XEPH asteroid ephemerides (currently JPL DE441 asteroid ephemerides).
- Perturbations from the 30 most massive Kuiper belt objects (KBOs). State vectors and constants are provided by XEPH asteroid ephemerides (currently JPL DE441 asteroid ephemerides).
- Relativistic perturbation terms (DE440's parametrized post-Newtonian (PPN) formulation) up to O(1/c^2) for the point–mass accelerations induced by all planets, Moon, Pluto and the five most massive asteroids.
Acceleration terms due to oblateness (zonal harmonics J2) have not been included in this release since their contribution is negligible to the accuracy of computed positional ephemerides for the set of objects in this numerical integration.
Please note that these files don't include the 343 most massive asteroids and the 30 largest Kuiper belt objects, which are already available directly on the PixInsight platform for a much larger time span (from 1550 to 2650) from DE440 ephemerides. So, if you are going to generate asteroid annotations, remember to include an Asteroids annotation layer besides custom XEPH layers.
The entire numerical integration executed to generate these 13 XEPH files (1.7 GiB) has required 15.5 hours on our new MARS-1 server: GIGABYTE R263-Z33 (rev. AAF1) server with an AMD EPYC 9654 96-core processor and 768 GiB of RAM running Kubuntu 22.04 LTS Linux. The integration has been performed by four simultaneous instances of the PixInsight core application, each limited to 40 processor cores.
We hope you enjoy this new release.