Ooh, I know this one! I worked on historical asteroid observations categorization and precovery for a few years.
The MPC has many observations of unidentified moving object candidates. These are called “tracklets” and come from pairs of observations of the same patch of the sky by the same observatory, separated (typically) by a few minutes.
The “isolated tracklet file”, or ITF, is a catalog of all of these unidentified moving objects.
When an identification is made and submitted to the MPC, the MPC back-projects the orbit and checks the ITF for any past observations which might have actually been of this newly identified object.
Then, the designation’s timestamp is of the first matching observation. So in this case the ITF had an observation from back in 2018.
Occasionally, two “objects” turn out to be the same actual physical object, but we learn late. In this case, the MPC does maintain a list of “aliases” of the object, so you might get that “aka” list. But that is not quite what happened here.
The MPC has many observations of unidentified moving object candidates. These are called “tracklets” and come from pairs of observations of the same patch of the sky by the same observatory, separated (typically) by a few minutes.
The “isolated tracklet file”, or ITF, is a catalog of all of these unidentified moving objects.
When an identification is made and submitted to the MPC, the MPC back-projects the orbit and checks the ITF for any past observations which might have actually been of this newly identified object.
Then, the designation’s timestamp is of the first matching observation. So in this case the ITF had an observation from back in 2018.
Occasionally, two “objects” turn out to be the same actual physical object, but we learn late. In this case, the MPC does maintain a list of “aliases” of the object, so you might get that “aka” list. But that is not quite what happened here.