CCD aided steering for an atmospheric Cherenkov telescope

Atmospheric Cherenkov telescopes (ACTs) usually suffer from small steering errors due to misalignments in both telescope axes. There are other sources of pointing errors which also degrade their performance, namely, permanent deformations on the telescope structure over the years and temporal deformation on the masts supporting the telescope camera during high zenith angle observations. s note, we present the results of an online method to correct these errors by use of a charge coupled device (CCD) camera. The method has been developed on the first Cherenkov telescope of the HEGRA experiment. The CCD, installed in the telescope’s dish, detects the telescope’s camera position and appropriate guide-stars to correct tracking. After this correction is applied the pointing shows measurable improvement. Other possible uses for the CCD camera on a ACT are also outlined. knowledge, this is the first time such a scheme has been used to correct online the steering errors in an ACT.