This "anomaly detection" framing seems underexplored in astronomy compared to other fields. In fraud detection or infrastructure monitoring, flagging outliers is standard practice. The fact that this is the first systematic anomaly search of the Hubble archive suggests there's probably low-hanging fruit in other telescope datasets too.
The "several dozen objects that defied classification altogether" is the most interesting part. Those are either noise, errors in the pipeline, or genuinely new phenomena. Would be curious what the false positive rate looked like during manual review.