In a gantry for an x-ray computed tomography apparatus with a rotor and a stator and a device for measurement of the rotation angle as well as a method for measurement of the rotation angle, a disc is provided with markings that rotate relative to a detection device for detection of the markings. Electrical signals are generated by the detection device, and an evaluation device converts the signals into a measurement signal corresponding to the respective rotation angle. To increase the precision of the measurement, a low-pass filter is connected upstream of the evaluation device.