Telescope guide and pointing precision at THEMIS

We present the very basic features—from the observer’s point of view—of the software pack allowing for driving the telescope, the dome, the preslit at the primary focus and the field rotator between the primary and the secondary focus. The original program was developed by C. Veillet as an adaptation for THEMIS of the program used to drive the “Laser-Lune” telescope at the Observatoire of the Cˆote d’Azur (France). Further adaptations were made by the authors to meet observational and technical needs emerged during operation of the THEMIS telescope. When talking about the way observations at THEMIS are affected by the pointing precisionw e clearly have to distinguish betweento different levels: 1) a short-term effect, affecting short-term observing actions such as scans on the solar disk and 2) a long-term level affecting the correct tracking of a target. All short-term effects just depend on the precision of the software interface and we discuss here their origin, the way they are controlled, their value and how they affect scanning procedures. All long-term effects depend on precision of the software interface but also on mechanical and optical alignment accuracy