argus-eyed, open-eyed, vigilant, wakeful (adj)

carefully observant or attentive; on the lookout for possible danger

"a policy of open-eyed awareness"; "the vigilant eye of the town watch"; "there was a watchful dignity in the room"; "a watchful parent with a toddler in tow"

vigilant (Adjective)

Watchful, especially for danger or disorder; alert; wary

Vigilant

Vigilant is a science fiction novel written by the Canadian author James Alan Gardner, published in 1999 by HarperCollins Publishers under its various imprints. The book is the third volume in Gardner's "League of Peoples" series, after Expendable and Commitment Hour.