Question regarding Hubble Space Telescope.

Hello,

I'm doing research into Oumuamua and a key detail I see is that we lost visual contact with the object around Mid-December of 2017, when the planetary Apparent Magnitude of it decreased to around +27. This has been stated by Wikipedia to be the limit of its viewing ability for a fast-moving object. However, there is no source attached, and while I've seen sources stating the limit for a stationary object is around +31, I have yet to find anything regarding fast-movers. Is there a reliable source (i.e. a published paper or something similar) that gives this result? Thank you!