The author's excellent 'powers of observation' [=ability to notice and pay close attention to things] are evident in the book's detailed descriptions.
The plants seem to have recovered from the disease, but they are still 'under observation'. [=someone is watching them carefully]
They're keeping him at the hospital 'for observation' [=so that doctors can watch him carefully] for another few days.
(..) - I don't know, but it sure makes me feel better Having you around. Yeah, I'll bet. - Do you mind if I make an observation? I think you should seriously consider How you're living your life. Where did that come from? - I saw your apartment, (..)2009 TvShow: Heroes Title: Chapter One 'Orientation/Jump, Push, Fall' Season: 4 Episode 1