Professional astronomers are typically dedicated to studying very specific things in space, and most of their time and energy is focused on those things. They don't usually have time to scan the heavens at random, looking for something unusual like this.
This is why, for example, most comets are discovered by (and named after) amateurs -- not professionals. The process of finding a comet in the night sky usually involves long, painstaking periods of time where an observer scans the night sky looking for something out of the ordinary -- like a small, blurry object in a constellation, that doesn't show up on sky charts. The best tools for this sort of thing are smaller telescopes with wide fields of vision -- because it would take forever to cover the entire night sky with one of those giant telescopes you see in an observatory.
See #67.
Thank you for the insights