On 21–22 April, experts from the CTAO Central Organisation and the Small-Sized Telescope (SST) Collaboration successfully established the first direct communication between the telescope structure and the Array Control and Data Acquisition (ACADA) software. As the central system that will eventually send commands to operate both CTAO telescope arrays, conducting integration tests between ACADA and the telescope is a critical pre-shipment milestone to minimise potential compatibility risks before the SSTs are delivered to the remote CTAO-South site in Chile. 

The rapid success of these integration tests was the direct result of exceptional synergy between the two groups. In the weeks leading up to the campaign, the SST Collaboration and the Central Organisation’s ACADA, Telescope, and System Integration teams worked together closely to lay the groundwork for the software deployment. This joint preparation paid off during the on-site work at the facilities of Dal Ben S.p.A., the company in charge of the mass production of the SST structures, in San Stino di Livenza, Italy. It took barely two days of joint, hands-on work at the factory for these two highly complex systems to successfully communicate with one another.

“Integrating the array control software with the instrument control software is a challenging transition for any observatory,” says Dominik Neise, ACADA Lead Developer. “The fact that the system responded accurately to our commands almost immediately significantly de-risks our schedule. We resolved a few minor issues on the spot, proving that our teams are fully aligned and capable of troubleshooting together under real-world conditions.”

During the tests, ACADA successfully executed commands instructing the telescope to perform repositioning and source tracking, whilst also retrieving monitoring data, such as temperature, from the sensors. Moreover, because only the mechanical structure is currently available at the Dal Ben S.p.A. factory, the SST camera team developed a simulation of the camera instrument. This allowed the teams to run the camera’s integration tests with ACADA, as well, ensuring a highly realistic, end-to-end testing environment.

“What is particularly encouraging is how smoothly the system behaved once connected to the real telescope structure,” says Vito Conforti, SST Telescope Control Software Lead and ACADA Release Manager. “This achievement reflects the extensive development and validation activities carried out across all Telescope Control Software subsystems, and the strong collaboration within the SST teams, from structure to camera, as well as with ACADA. It provides clear evidence that the adopted approach is robust and that the system is well prepared for the next phases of integration.” 

The CTAO SST Collaboration is an In-Kind Contribution team tasked with developing and building the SSTs. Ultimately, 37 of these telescopes will be integrated into the CTAO-South array in Chile to study the highest-energy Universe. Following their installation and commissioning, they will be formally accepted by the Central Organisation for operation as an integral part of the Observatory. 

With this first round of command execution and data exchange completed successfully, the teams will return to the Dal Ben S.p.A. factory in early May for the final phase of the testing campaign. Confidence remains exceptionally high as the project moves steadily towards shipment and installation of the first SSTs at the CTAO-South array this year.