A go-around is a plane that came down the approach at St. Paul or St. George and climbed back out instead of landing — almost always the fog. A hold is one that stayed within 15 NM of the field for eight minutes or more, turning, waiting for a gap — or circling for a look. Both are found in our own minute-by-minute ADS-B history; every go-around since the receiver went up is on the books, and each one can be replayed — press play to watch the approach, the climb-out and where the plane went next.
A second watcher reads the live feed and flags aircraft whose track folds back on itself. A racetrack or grid usually means survey or patrol work — fisheries observation, marine mammal counts, or aerial mapping. A circle is typically a hold, an orbit over something of interest, or training. Detection is geometric, not a statement of intent.