  The Cherenkov Telescope Array Observatory (CTAO) will be the largest and most
advanced ground-based facility for gamma-ray astronomy. Several dozens of
telescopes will be operated at both the Northern and Southern Hemisphere. With
the advent of multi-messenger astronomy, many new large science infrastructures
will start science operations and target-of-opportunity observations will play
an important role in the operation of the CTAO. The Array Control and Data
Acquisition (ACADA) system deployed on each CTAO site will feature a dedicated
sub-system to manage external and internal scientific alerts: the Transients
Handler. It will receive, validate, and process science alerts in order to
determine if target-of-opportunity observations can be triggered or need to be
updated. Various tasks defined by proposal-based configurations are processed
by the Transients Handler. These tasks include, among others, the evaluation of
observability of targets and their correlation with known sources or objects.
This contribution will discuss the concepts and design of the Transients
Handler and its integration in the ACADA system.
