Adjective : a vigilant sentry.    From Dictionary.com. 

We figured these Vigilant Ones would be interested in cracking down on the rather unvigilant Jet Blue and the screeners at the Nashville airport.    From Wordnik.com.  [July 2007] Reference

Like Tariq Ramadan, also touted by the unvigilant and ill-informed as a great moderate.    From Wordnik.com.  [National Review Online] Reference