On the Transients Handler for the Cherenkov Telescope Array Observatory

Abstract: The Cherenkov Telescope Array Observatory (CTAO) is a next-generation gamma-ray observatory in both the Southern (Paranal, Chile) and Northern Hemisphere (La Palma, Spain) and will consist of up to 100 imaging atmospheric Cherenkov telescopes. With sensitivity far exceeding current facilities, CTAO will provide detailed measurements of gamma rays from GeV up to a few 100s of TeV. CTAO has a nominal field of view of 10{\deg} and will rely on external alerts from observatories such as IceCube (neutrinos), Fermi-LAT (GeV gamma rays), LIGO (gravitational waves (GWs)) or the upcoming Vera C. Rubin Observatory (optical) to trigger observations of targets of opportunity (ToOs). The Transients Handler (TH) is a subsystem of the Array Control and Data Acquisition that will provide the means of handling alerts and schedule follow-up observations. The TH is responsible for (i) filtering of thousands of internal and external alerts per night, (ii) processing of alerts according to the corresponding observation proposal to determine the optimal observation schedule with minimum interruptions to observations and (iii) broadcasting of events detected by CTAO to external facilities. In this work, we will discuss the architecture of the Transients Handler, its latest improvements and future updates