NGC7000.COM
Updating comets and asteroids in COELIX APEX

Orbits of comets and asteroids are easily disturbed by the gravitational attraction of large planets in the solar system, like Jupiter and Saturn, and even by the other planets like the Earth.The orbital elements of comets and asteroids (eccentricity, inclination, semi-major axis, etc.) can be modified when these bodies pass near large planets.

Because of this, these orbital elements are only valid for a limited period of time. For this reason and because we often discover new comets and asteroids, it becomes necessary to regularly update the database of comets and asteroids in COELIX. It is recommended to do updates at intervals ranging from two to six months. In this way, the software can generate accurate ephemeris and trajectories of these objects,

Accessible comets and asteroids in COELIX APEX

Not all of the hundreds of updated comets and the thousands of updated asteroids are directly accessible in COELIX APEX. See the help section on comets and asteroids in the software to learn how to make these objects accessible and what is the priority when a comet or an asteroid is present in more than one database (eg: both in the orbital elements coming from the MPC and from the JPL).

Complete list of comets from the JPL (Jet Propulsion Laboratory)

The complete list of comets from the JPL includes the orbital elements of all the comets discovered and known so far. This list contains over 3000 comets (early 2013). You will find the orbital elements of famous comets that are not currently visible, like Halley's comet.

The database of this group of comets is already contained in regular updates of COELIX APEX. You do not need to do separate updates for these comets
Numbered asteroids from the JPL

In addition to the hundreds asteroids from the MPC, the COELIX database can hold all asteroids numbered by the IAU (International Astronomical Union), that is more than 488,000 asteroids (updated as March 2017). Orbital elements of these asteroids are calculed by the MPC and the JPL (Jet Propulsion Laboratory).

This database of asteroids is already contained in regular updates. You don't have to do a separate update.

Comets and asteroids from the MPC (Minor Planet Center)
You access the MPC files containing the orbital elements of the chosen objects. Each file contains the text file of the table of orbital elements, for example the file Soft01Cmt.txt for the comets.

You can obtain tested copies of these files by clicking the buttons at right.

In each case, save the page in the main folder of COELIX software, for example C:\COELIX, by using the function Save
_as... of your web browser and without changing the filename.



MPC Website
Tested copies updated
on March 16, 2017.
If you find that the tested copies above are too old, you can download the files directly from the MPC site, by clicking the buttons at right.

In each case, save the page in the main folder of COELIX software, for example C:\COELIX, by using the function Save
_as... of your web browser and without changing the filename.

Even more precise ephemeris from the JPL HORIZONS System

All downloaded files above contain the orbital elements of comets and asteroids. Coelix uses the orbital elements (perihelion distance, inclination, semi-major-axis, etc..) to calculate the ephemeris and positions of comets and asteroids. These calculations give accurate results in most cases.

However, the downloaded orbital elements are osculatory, that is to say that they change over time and that they are only valid for a limited period. In addition, Coelix calculations do not include the effects of gravitational perturbations from objects other than the Sun, such as planets and large asteroids. So there may be a discrepancy in some cases, especially when a comet or asteroid passes close enough to Earth.

Since the 2.094 version, Coelix includes dozens of comets and asteroids whose ephemeris are directly calculated by the JPL Horizons system. These give very accurate ephemeris positions that reflect the gravitational perturbations.

Normally, you do not need to separately download these ephemeris because they are part of regular updates of Coelix.

CLICK HERE to see the list of comets and asteroids whose ephemeris are directly calculated by the JPL Horizons system and are part of the list in the current version. You will also see how to add yourself comets and asteroids that are not in the list.