Noticed, viewed (4)
I believe the answer is:
seen
I believe this clue is a double definition.
'noticed' is the first definition.
(I've seen this in another clue)
'viewed' is the second definition.
(to view is to see)
(Other definitions for seen that I've seen before include "Witnessed" , "Spotted" , "Viewed" , "Sighted" , "watched" .)