It is possible in the Online Activity Dashboard to see activity that has been during certain hours but unable to deeper dive to see who those users are that shouldn't be online at those hours. you can look at this over a period of a week or however long but to find out more information you have to go to web activity and can only filter time day by day. ability to either deeper dive within the dashboard to see more information or ability to run the report over more than 1 day.