The motivation is simple: ssObjectId = 0 describes the association state when an alert was generated, but it does not necessarily mean that the detection belongs to a new object. Before searching systematically for new Solar System objects, I am trying to remove observations of already known asteroids and comets as completely and reproducibly as possible.
The pipeline combines public alerts obtained through Fink with current MPC/SBN orbital data. Candidate matches are searched using PostgreSQL/Q3C and accepted only after orbital refitting, residual checks, and evaluation of their effect on the full observational arc.
The current catalog contains more than 250,000 additional associations, together with diagnostics for rejected, ambiguous, duplicated, or unstable fits.
This is an early MVP and should be seen simply as an independent experiment in reconciling alert-time associations with current orbital knowledge.
I would be grateful for any comments, corrections, or suggestions—especially regarding methodology, possible biases, useful Rubin data products, or interfaces I could incorporate. I am very open to implementation changes and future updates.
Interesting. During commissioning, one assumes various possible linkages may be missed. As the survey reaches its steady state, however, your pipeline really ought to be responsive to why Rubin and/or the official SSSC pipelines didn’t accept the linkage. Whatever the pipeline making the associations, there are a number of reasons one might choose not to assert a linkage:
Is the object detected in both visits?
Does the magnitude closely match that estimated from the ephemeris?
Is there source confusion? (with either background astrophysical sources or other moving objects or imaging artifacts)
Does the object in question already have another linkage in the same field?
Are there other solar system objects to which the source detection might link?
Are there reasons (too many to list) to believe this might not be a solar system detection? Does your pipeline compare the source location against other transient catalogs, for instance?
About the latter, to the other science collaborations, a primary goal of making solar system associations is to clean the list of transients of these vermin of the sky. I don’t know what the threshold is, but at some level of confidence, they will want an uncertain solar system identification to remain unmade to allow their own pipelines to make inferences.
Most unlinked / unidentified detections will be close to the limiting magnitude in each band. Pipeline performance (yours and other people’s) will naturally degrade at the faint end.