In the derived catalog 'currentcat' I have added about 700 objects with 'C' prefixes.
These are debris objects tracked by the US Space Force which they have not identified
with a specific launch.
Analyst Objects in the Space Force Catalog
The main, public US Space Force catalog has a running catalog number starting
with 1 (Sputnik 1 rocket stage) and going to currently somewhat over 51000.
The criteria for a previously undetected debris object being added to the catalog are traditionally:
- Object remained in space for more than one full orbit
- Object's orbit is well determined and followed over a period of time (many orbits).
I will refer to this as it being a `persistent object', as opposed to radar tracks that
are not seen again. (For astronomers: This is analogous to the difference between a minor planet with a provisional
designation and one with a permanent asteroid number.)
- Object is identified as being from a specific launch, so that it can get an `international designation'
The Space Force also generates orbital solutions for objects which do not yet meet these criteria,
but might later get added to the catalog. These are called `analyst objects' (the data will
be studied by analysts for possible later identification). Historically these
are assigned fake catalog numbers between 80000 and 90000 (and possibly between 70000 and 80000,
although the orbital data for those has not generally been released). More recently, objects
detected by the Space Fence have been given numbers starting at 270000.
A few datasets of the analyst object TLEs became public (possibly inadvertently) over the years,
and then in 2020 a subset of analyst TLEs started being regularly released by 18SPCS on Space-Track.org.
To distinguish the analyst objects, I add them to my supplementary CSOCAT catalog (which also
contains objects from other sources such as hobbyists). CSOCAT catalog numbers in
the ranges 80000-89999 and 270000 upwards are reserved for US Space Force analyst object TLEs.
These objects fall in several categories:
- Assorted TLEs: analyst catalog numbers with several TLE sets referring to several different
objects in entirely different orbits. These numbers are apparently reused at will and do not
refer to a single persistent object.
- Fake (Search) TLEs: TLEs which appear to be associated with prelaunch estimates of a known
object rather than being based on actual tracking data.
- Poorly tracked objects, with only one or two TLE sets, and those from many years ago.
- Old, retired analyst objects: analyst catalog numbers with several TLEs in my archive, but
none referring to recent epochs. In particular, a lot of objects in the 1994 and 1998 analyst
datasets available to me don't appear in the modern (2020 onwards) TLE data releases. I have
assigned them status OX (lost), but in many cases it's possible they have been moved to the
main catalog with a new catalog number. I have identified a handful of cases like that, but
haven't worked to make systematic cross-identifications.
- Persistent analyst objects: analyst catalog numbers for which the TLEs since 2018
clearly refer to one specific object (the orbit changes slowly) and which continue to
get new updated TLEs in the past year or so.
- Space Fence objects: the objects with catalog numbers above 270000. All of these
(with a handful of exceptions) appear to be persistent analyst objects.
- Unreleased analyst objects. The Space-Track.org `Space Scoreboard' says that there
are (as of Feb 2022) 17600 analyst objects, many more than data is being released for.
Objects in the CurrentCat
Only the `persistent analyst objects' are really of interest, as real well-tracked
objects which would be in the main catalog if they were associated with a known launch.
As of Feb 2022 there are a little
under 700 of these. This is just a few percent of the number of tracked debris objects in orbit,
and a small number compared to the 17600 such objects reported to exist by 18SPCS.
All the analyst objects for which I have any data are included in the Complementary Catalog `csocat'.
Use that data with care, since they include objects which are not necessarily real, and ones which
have been reassigned with new numbers elsewhere.
The 700 robust `persistent analyst objects' are now included at the end
of the derived product `currentcat' so that they can be used in
Tentative Identifications of Analyst Objects
I have attempted to identify these analyst objects.
In some cases one can infer the
parent launch with fairly high confidence - for example objects from the 1965 SNAPSHOT
launch which have distinctive orbital parameters.
In other cases one can only
identify them as being from one of a handful of launches - there is a debris cloud
at high inclination which is dominated by debris from three different Delta rocket stages
that exploded in Dec 1973 (Delta 98),
Aug 1975 (Delta 104), and Dec 1977 (Delta 126). You can be pretty sure that
certain debris objects belong to one of those three launches, but you can't tell which.
For now I have arbitrarily picked one of the launches to assign to the objects but indicate the
ambiguity in the object name.
In still other cases, notably for LEO sun-synchronous objects and many Molniya
orbit and geotransfer orbit objects, there are too many possible parent launches
to make a specific identification. In these cases I do not assign an international designation
and give the object a generic name like "Unknown SSO debris".
In future I hope to take a more rigorous approach by creating new designations for specific