I work on asteroid/comet orbit calculations for my day job. I had not actually seen this paper before, though I have done some detective work in old Palomar images in the past: https://caltech-ipac.github.io/kete/tutorials/palomar.html

I spent a few minutes and downloaded the image frame they cite in the paper and ran it through a similar analysis looking for known asteroids, and there were no known asteroids in that patch of sky at that time (didn't really expect any, as I would expect them to be causing a visible streak over the 10 minutes of exposure). Neat paper though!