Navigation: Deep-Sky Planner Help > Options Menu > Orbital Elements Manager >

Orbital Elements Editor

The Orbital Elements Editor is used to add or modify the elements that define the orbit of a comet or asteroid. Orbital element data are made available online courtesy of the Minor Planet Center (MPC) and NASA/JPL Solar System Dynamics (SSD). These elements can be entered individually using the Orbital Elements Editor, or added en masse using the Import facilities of the Orbital Elements Manager.

The elements to be input vary slightly between comets and asteroids.

The Orbital Elements Editor dialog box

For Comets

Object Name is assigned by the International Astronomical Union (IAU) and may be up to 30 characters in length. The name must be unique.

Epoch of osculation (optional) should be entered for perturbed solutions as year, month (1-12) and day of month (not decimal form.) This value may be missing for some objects.

Passage through perihelion (T) should be entered as year, month (1-12) and decimal day of month.

Argument of perihelion (w) in degrees should be entered in decimal degrees and is referred to standard equinox 2000.0

Mean motion (n) in degrees per day is calculated for you and displayed in decimal degrees.

Longitude of ascending node (omega) in degrees should be entered in decimal degrees and is referred to standard equinox 2000.0

Semi-major axis (a) in AU is calculated for you and displayed in decimal form.

Inclination (i) in degrees should be entered in decimal degrees and is referred to standard equinox J2000.0

Eccentricity (e) should be entered in decimal form.

Total absolute magnitude (g) should be entered in decimal form. This value may be missing for some objects.

Perihelion distance (q) in AU should be entered in decimal form.

Total magnitude slope parameter (k) should be entered in decimal form. This value may be missing for some objects.

If you want this object to appear in a Comet Ephemeris document, you must check Favorite.

Press OK to accept the changes, or Cancel to leave the elements unchanged.

For Asteroids

Object Name is assigned by the International Astronomical Union (IAU) and may be up to 30 characters in length. The name must be unique.

Epoch of elements should be entered for perturbed solutions as year, month (1-12) and day of month (not decimal form.)

Mean Anomaly at Epoch (M0) in degrees should be entered in decimal degrees.

Argument of perihelion (w) in degrees should be entered in decimal degrees and is referred to standard equinox 2000.0

Mean motion (n) in degrees per day should be entered in decimal degrees.

Longitude of ascending node (omega) in degrees should be entered in decimal degrees and is referred to standard equinox 2000.0

Semi-major axis (a) in AU should be entered in decimal form.

Inclination (i) in degrees should be entered in decimal degrees and is referred to standard equinox 2000.0

Eccentricity (e) should be entered in decimal form.

Absolute magnitude (H) should be entered in decimal form. This value may be missing for some objects.

Magnitude slope parameter (G) should be entered in decimal form. This value may be missing for some objects.

If you want this object to appear in a Asteroid Ephemeris document, you should check Favorite.

Press OK to accept the changes, or Cancel to leave the elements unchanged.

What About?

The orbital elements of comets and asteroids are revised periodically by the MPC or SSD. You should check for updated orbital elements so that improved orbital solutions produce the most accurate ephemerides. Orbital elements for newly discovered objects are revised much more frequently.

If you do not check Favorite for an object's elements, you will not be able compute an ephemeris for it because the object will not be available to the ephemeris or search documents; however, the object's elements will be stored in the database so that you can make it a Favorite later, thereby making the object available to the ephemeris and search documents.

Comet Naming Formats

MPC and SSD use the same naming conventions for comets ...

Periodic comets have an orbital period < 200 years and multiple apparitions from which to compute elements.

▪MPC names short-term periodic comets with numbers, 'P' and names like 1P/Halley.

▪SSD names short-term periodic comets with numbers, 'P' and names like 1P/Halley.

Provisional Periodic comets have a period < 200 years and only one apparition from which to compute elements.

▪MPC provisionally names short-term periodic comets with 'P', date codes and names like P/2023 X3 (PANSTARRS)

▪SSD provisionally names short-term periodic comets with 'P', date codes and names like P/2023 X3 (PANSTARRS)

Long Period

▪MPC names long-period comets with 'C', date codes and names like C/1995 O1 (Hale-Bopp)

▪SSD names long-period comets with 'C', date codes and names like C/1995 O1 (Hale-Bopp)

Other

▪MPC A/2023 R3, D/1993 F2-D (Shoemaker-Levy), 1I/`Oumuamua

▪SSD

Asteroid Naming

MPC and SSD use different naming conventions for asteroids ...

Numbered asteroids with names are objects with many observations from which to compute elements.

▪MPC names these asteroids with a number and a name like (1) Ceres or a number only like (164121). Note the parentheses around the number in the MPC format.

▪SSD names these asteroids with a number and a name like 1 Ceres. Note the LACK of parentheses around the number in the SSD format. SSD also names these asteroids with a number and a date code

Unnumbered asteroids have only date of discovery codes because they have too few observations from which to compute elements. They are not assigned numbers.

▪MPC names these asteroids with date codes like 1994 ES2

▪SSD names these asteroids with a date codes like 1994 ES2