GCAT: General Catalog of Artificial Space Objects

GCAT Release 1.5.7 (2024 Oct 18) | Data Update 2024 Dec 25

Worlds Table Column Descriptions

Each line in the Worlds table represents a world, a small body, or a dynamical point.

The fields in the Worlds table are described below. The important fields are the name, mass, and radius. The orbital data given (columns from SemiMajorAxis through Epoch, and EphPeriod), as well as the RotPeriod, are sample values and it should be noted that the elements are functions of time - especially for moons. In practice, detailed ephemerides such as the JPL data are used to compute the locations of the worlds, and the values in this table are just to give the reader a general idea.

• ID: This one or two character string defines what kind of IDName designation the body has. (This also hints what kind of world it is, but that is formally defined in the WType field). The values are described in the next (IDName) paragraph.
• IDName: Combined with the ID field, the IDName provides a unique identifier for the body. These are based on the standard astronomical designations for the bodies except for the planets and moons which use the JPL ephemeris codes for the objects. (The identifiers are explained below, but it's fine to treat them as opaque strings rather than parse them).

  
  

  ID	IDName Format	IDName Examples	Category	Description
  P	0nn	006	Planet or Moon	Three digit code. 001-010 are `planets'including Pluto (9) and the Sun (10).
  P	pnn	603		Values 301-999 represent moons. The first digit is the primary and the second is the moon number for that primary, so 603 is the third officially numbered moon of Saturn (Tethys).
  DL	ABLn	SEL2	Lagrange point	L Point n for the Alpha-Beta system is ABLn. The letter abbrevations for the bodies are, however, arbitrary.
  A	(nnnn)	(532037)	Numbered minor planet	Value in parentheses is the minor planet number, starting with (1) Ceres.
  AP	yyyy ABnnn	2002 TC302	Provisionally designated minor planet	IAU MPC provisional designation code, starting with discovery year.
  AS	(nnn) m	(90482) 1	Satellite of minor planet	moon number m of asteroid nnn is (nnn) m.
  C	nnP/	21P/	Comet	Comet designations ending in P/ are numbered periodic comets.
  C	C/yyyy An	C/2017 S8	Comet	Comet designations starting C/ or D/ are `unnumbered' non-periodic coments.

• Name: Name of the body. This name is used to identify the central body around which an object is orbiting in the General Catalog object catalogs and in the XTLE (extended TLE) orbit data files.
• AltName: Alternate name of the body. Either the formal designation with respect to the object's primary (e.g. Earth is Sol III) or an asteroid provisional designation.
• Radius: The equatorial radius of the body in km. A trailing question mark indicates an uncertain estimate.
• Polar radius: Polar radius of the body in km, where known.
• Mass: Mass of the body in teratonnes (1E15 kg, or 1E18g). A trailing question mark indicates an uncertain estimate. A trailing letter M (for million) indicates the numerical value should be multiplied by 1,000,000.
• SemiMajorAxis: Semi-major axis (orbital radius) of the body's orbit around its primary, in km. A trailing question mark indicates an uncertain estimate. A trailing letter M (for million) indicates the numerical value should be multiplied by 1,000,000.
• Periapsis: Periapsis (minimum orbital radius) of the body's orbit around its primary, in km. Note that for comets, the periapsis is often much more accurately known than the semi-major axis. A trailing question mark indicates an uncertain estimate. A trailing letter M (for million) indicates the numerical value should be multiplied by 1,000,000.
• Ecc: Orbital eccentricity at the given epoch.
• Inc: Orbital inclination at the given epoch. Moon orbits given with respect to planetary equator. Heliocentric orbits given with respect to the J2000 ecliptic.
• Node: Longitude of ascending node at the given epoch. Moon orbits given with respect to planetary equator. Heliocentric orbits given with respect to the J2000 ecliptic.
• Peri: Argument of periapsis at the given epoch.
• M: Mean anomaly at the given epoch.
• Epoch: Epoch of the sample orbital elements (SMA, periapsis, ecc, inc, node, peri, M).
• RotPeriod: Rotation period of the body in days. (More detailed information given in the Spin file).
• OrbPeriod: Orbital period of the body in days.
• Ephemeris: A string which encodes which ephemeris should be used to supersede the given orbital elements. Currently, JPL ephemeris files are used (DE405 for the planets and SPICE files for the moons.)
• WType: Body (world) type. Types used are:

  WType	Meaning
  *	Star
  A	Minor planet (asteroid)
  AS	Asteroid satellite (moon of asteroid)
  DB	Barycenter dynamical point
  DL	Lagrange dynamical point
  M	Small moon
  P	Major planet
  W	World (but not major planet)
  CP	Periodic comet
  C	Comet

• Primary: Central body which this body is orbiting. When not given, it is assumed the central body is the Sun. The string EMB is an alternate name accepted for 'Earth-Moon System', the body entry from the Earth-Moon barycenter.