Optimisation of the Drive Software for the Medium-Sized Telescopes of the Cherenkov Telescope Array

Abstract

The Cherenkov Telescope Array (CTA) is the next-generation ground-based observatoryfor gamma-ray astronomy at very high energies. In its initial Alpha Configuration, itwill consist of 64 imaging atmospheric Cherenkov telescopes (IACTs) of different size anddesign, which will be deployed in the form of two large arrays in the northern hemisphereat the Roque de Los Muchachos Observatory on La Palma (Canary Islands, Spain) andin the southern hemisphere at the Paranal Observatory in the Atacama Desert (Chile),respectively. The core energy range of CTA (approximately 100 GeV to several TeV) willbe covered by the Medium-Sized Telescopes (MSTs), which are planned to be built atboth sites.Observations of astronomical targets with MSTs are facilitated by the drive system, mov-ing the telescope in elevation and in azimuth direction, respectively. It is steered and con-trolled by the drive software, which uses the OPC Unified Architecture (OPC UA) stan-dard to communicate with the programmable logic controller (PLC) operating the drivemotors, and is implemented on top of the ALMA Common Software (ACS) framework(except for the PLC). In this contribution, the architecture of the MST drive software willbe presented. A particular focus will be on the description of the newly-developed softwarelibrary of the MST drive system and its algorithms for the generation and optimisationof the time-dependent trajectories which the telescope follows during the observation ofastronomical targets