CATO was an agency or title held by a Starfleet officer at Starfleet Command's Fleet Operations Center, Sol Sector.
In January of 2155, Starfleet officer P. Corcoran-Woods was working in or as CATO. It and the officer's name was listed on directory placards. (ENT: "Demons", directories)
CATO, like many of the other agencies or titles on the directories, was a reference to NASA and ISS terminology, in this case, the "Communication and Tracking Officer".