Monitor that checks for credentials request (HTTP 401?)

The site that we need to monitor uses HTTPS, and when we go to the site, it pops up a login box that asks for AD-ENT credentials.

How do I setup a monitor in ipMonitor that checks for this credentials request? I don't want the monitor to authenticate, I just need the monitor to check that the page is responsive and asks for AD-ENT credentials.

Thank you!