Antonyms of adj unobserved

2 senses of unobserved

Sense 1
unobserved, unseen -- (not observed)

INDIRECT (VIA undetected) -> detected -- (perceived or discerned; "the detected micrometeoritic material")

Sense 2
unobserved -- (not observed; "managed to slip away unobserved")

INDIRECT (VIA unnoticed) -> noticed -- (being perceived or observed; "an easily noticed effect on the rate of growth")

Similarity of adj unobserved

2 senses of unobserved

Sense 1
unobserved, unseen -- (not observed)
       => undetected (vs. detected) -- (not perceived or discerned; "they feared some undetected trace of poison"; "she looked around to be sure her faux pas was undetected")

Sense 2
unobserved -- (not observed; "managed to slip away unobserved")
       => unnoticed (vs. noticed) -- (not noticed; "hoped his departure had passed unnoticed")