Pointing calibration is an offline correction applied in order to obtain the true pointing direction of a telescope. The Cherenkov Telescope Array (CTA) aims to have the precision to determine the position of point-like as well as slightly extended s
ources, with the goal of systematic errors less than 7 arc seconds in space angle. This poster describes the pointing calibration concept being developed for the CTA Medium Size Telescope (MST) prototype at Berlin-Adlershof, showing test results and preliminary measurements. The MST pointing calibration method uses two CCD cameras, mounted on the telescope dish, to determine the true pointing of the telescope. The Lid CCD is aligned to the optical axis of the telescope, calibrated with LEDs on the dummy gamma-camera lid; the Sky CCD is pre-aligned to the Lid CCD and the transformation between the Sky and Lid CCD camera fields of view is precisely modelled with images from special pointing runs which are also used to determine the pointing model. During source tracking, the CCD cameras record images which are analysed offline using software tools including Astrometry.net to determine the true pointing coordinates.
We present here the status of the medium size prototype for the Cherenkov Telescope Array. The main reasons to build the prototype are the test of the steel structure, the training of various mounting operations, the test of the drive system and the
test of the safety system. The essential difference between the medium size telescope prototype and a fully instrumented are that the camera is not instrumented and only a part of the mounted mirrors are optical mirrors. Insofar no high energy gamma rays can be detected by the prototype telescope. The prototype will be setup in autumn 2012 in Berlin.
