GCAT: General Catalog of Artificial Space Objects

GCAT Release 1.5.5 (2024 May 5) | Data Update 2024 Jun 29

Current Object Catalog Column Descriptions

The Current Catalog (currentcat) gives information on the current status of each object, including the most recent orbital data for those objects still in orbit. All the info in currentcat is implicit in, and derived from, the main catalogs. Its role is to provide an easy summary of the satellite catalog for those not interested in the most detailed nuances.

• The first few fields (JCAT, Satcat, Piece, Type, Name, PLName, LaunchDate) identify the object and name it.
  • JCAT The General Catalog (GCAT) uses an alphanumeric identifier (JCAT, originally Jonathan's Catalog ID) to uniquely tag space objects. The identifier consists of a single prefix letter followed by a sequence number with either 5 or 9 digits (examples: A00022; S101234009). The 9 digit case is not yet in use, but is supported in anticipation of the introduction of 9-digit SATCAT numbers by the US DoD.

    
    The leading letter tells you which object catalog the object belongs to, as follows:

    JCAT letter	Catalog
    A	auxcat (Auxiliary catalog)
    C	csocat (Complementary catalog)
    D	deepcat (Deep space catalog)
    F	ftocat (Failed to orbit catalog)
    L	lcat (low altitude catalog)
    R	rcat (suborbital catalog)
    S	stdcat (Standard catalog)
    T	tmpcat (Temporary catalog)

    
    Note that there are no prefix letters associated with the ecat (event catalog), or the heliocentric and lunar-planetary registers, since they contain only objects already defined in the other catalogs.

    
    Sequence numbers in the A, D, F, L, R, and S catalogs are assigned sequentially starting with 00001. However, occasional numbers may be missing due to deletions of spurious or reassigned entries.

    
    Sequence numbers in the C and T catalogs are not assigned sequentially.

    
    Sequence numbers in the S catalog are in one-to-one correspondence with the US SATCAT catalog numbers. Thus, S46112 corresponds to SATCAT satellite 46112 (2020-056A).

    
    In exceptional cases, future releases of GCAT may reassign existing catalog numbers. Any such reassignments will be recorded explicitly in an accompanying table. However, users who have found earlier (pre-GCAT) JCAT catalog numbers that crept into my public files have no such guarantee - in partcular, auxcat numbers previously seen in public files may now refer to different objects.

  • Satcat For objects in the US Satcat, this field contains an integer value which is the US SATCAT number. In the S catalog, this will be the same as the JCAT sequence number.

    
    However, one US SATCAT number can correspond to multiple GCAT objects which are attached to one another. For example, SATCAT number 00032 corresponds to GCAT objects S00032 (Discoverer 11 payload), A00046 (Agena 1055 rocket stage), and A00047 (TOD experiment attached to Agena stage). All these objects have 00032 in the Satcat field.

    
    Objects which do NOT have US SATCAT entries instead have a string in this field explaining why they don't.

    Value	Meaning
    NNA	No (satcat) Number Assigned. Object should be in SATCAT but is not.
    NNA A	No SATCAT number because remained attached to parent object
    NNA C	No SATCAT number, component of complex object such as space station
    NNA E	No SATCAT number because is an EVA spacesuit. These do not get recorded in SATCAT.
    NNA I	No SATCAT number because object remained inside parent object
    NNA P	No SATCAT number because completed less than one full orbit
    NNA R	No SATCAT number because separated into marginally suborbital trajectory during parent reentry.
    NNA S	No SATCAT number because launched into marginally suborbital trajectory
    NNA T	Not in SATCAT because object was a separate object in orbit transiently, for only a few seconds (e.g. CORONA film capsule)
    NNA X	Not in SATCAT because launch is a marginal orbit case
    NSO	No SATCAT number because suborbital

  • Piece The piece designation for the object. For objects in the US SATCAT this is the COSPAR (International) designation (e.g. 2020-032A). See the section on launch and piece designations in `definitions and conventions' for details.
  • Ac This field has a single byte giving the type of object as follows:

    A	Active satellite
    C	Component (see SatType explanation)
    D	Debris (see SatType explanation)
    P	Inactive payload
    R	Rocket stage
    Z	Spurious entry

    Except for A, the values are usually the same as the first byte of the Type field.
  • Type This field contains a SatType string as defined in the SatType section. This field tells you something about what kind of object this is. At the coarsest level, we characterize the object as payload (P), rocket stage (R), component (C) or debris (D). A component is a functional part of the spacecraft or rocket that is deliberately or accidentally ejected - a fairing, for example. A debris object in this sense is a fragment from a satellite breakup, usually accidental - although fragments from deliberate explosions or collisions are included in this category.

    
    At a finer level the type string provides a lot more information for special cases. See the SatType definition for more details.

  • Name My recommended name for the object. The name is based on that used by the owner/operator of the object. In cases where the original name is in a non-Latin character set, see the associated GCAT unicode name list for a representation of the name in Unicode.

    
    `X part' indicates that the object is an unidentified component that separated from X. `deb X' indicates the object is a debris object from the breakup of X.

  • LDate (Launch Date).

    
    The launch date is given in UTC, with 1 day precision. More accurate launch times are given in the launch lists. Usually you can map the object to a launch using the international designation, but see the discussion in the Parent field below for exceptions.

• Parent The Parent field can be either
  • the `parent object' which the object is attached to at the start of the phase, or
  • the central body whose gravitational sphere the object is leaving at the start of the phase.

  
  The parent object is an Extended JCAT Identifier - it's usually just a JCAT ID but sometimes there's a port location appended to make it more specific. See the documentation on the main satcat for more details.

  
  

• Owner The owner is the organization which currently owns the object if it is still in space, otherwise the organization which owned the object at the time of reentry. This is in contrast to the primary GCAT catalogs in which owner is that at the time of the start of the phase being listed.
• State The country (or equivalent) associated with the owner.
• SDate Separation Date

  
  This UTC date (in Vague Date format) is the time when the object first separated from its parent. Details of subsquent phases (dockings/undockings, etc) are not given in this catalog - see the main catalogs for details. This date is useful for determining when debris objects appeared in orbit, for example.

• ExpandedStatus This field gives the current status of the object. It is derived from the Status and Dest fields for the most recent phase of the object in the basic Object Catalogs, and is intended to be self-explanatory (YMMV).
• DDate Descent Date

  
  This UTC date (in Vague Date format) is the time when the object reentered the atmosphere or landed. If blank, the object is still in orbit.

• ODate Orbit Epoch Date. UTC epoch of most recent orbital data, Vague Date format.
• Perigee, PF Conventional perigee height in km of most recent orbit. Equal to perigee radius minus equatorial radius of central body.
• Apogee, AF Conventional apogee height in km of most recent orbit. Equal to apogee radius minus equatorial radius of central body.
• Inc, IF Inclination of most recent orbit in degrees with respect to coordinate system equator. Heliocentric orbits are given with respect to the J2000 ecliptic. Earth orbits are given with respect to the equator of date (strictly, TEME equator). Orbits around other central bodies are given with respect to the IAU equator of that body.