I think the Dec limitation is far less relevant now but searching deep in the Milky Way is still a big problem. The original Pan-STARRS spec. took 2 to 8 images of the same field each night. The software looked for two rates of motion, 0.75″ to 1.75″/minute (slow) and 3″ to 12.5″/minute (fast). Of course, NEOs are the main target, not comets. The reason for the gap was that software searching for faster than 1.75″/minute produced loads of false suspects, but faster than 3″/minute these could be eliminated because the genuine NEOs would reveal a slight trail in 30 to 60 seconds. Some time ago Pan-STARRS stated their software had now closed the false-alarm gap, ‘away from the Galactic plane’…. So I guess that at an average rate of motion in the gap of 2.4″/minute, objects in the densest part of the Milky Way can still evade detection? There are charts of sky patrol coverage on the MPC website. Unfortunately due to the MPC computer crash of a few months ago these are not up to date, but sky coverage from earlier this year can still be checked…Unfortunately the charts are in RA and Dec only but they do show how dense the Sky Coverage is! The page is at
https://minorplanetcenter.net/iau/SkyCoverage.html
You fill in the details and hit ‘Generate Plot’…..
Martin