To know the inaccuracy of the constellation clock, by the transit instrument, by observing the sun or the stars, with the help of a machine named chronometer, the constellation of their posthumous period is known.
Combining the sidereal clock, in the telescope of the post-machine instrument, the constellation of the planet or the star of the star is known by pressing the switch of the chronometer. From this time, the time when the mechanical impurities are removed, it is time to skip the vertical point of the planet or the posture of the star. If the constellation is right then it will be like the planet or the star of the equinox and the difference is the inaccuracy of the clock. Thus, keeping the constellation clock pure, the mean sun clocks are purified. The possibility of personal inaccuracies to be detected by post-operative devices is more. Therefore, the constellation time of epochal climbing of the stars is also known by the zenith tubes found in the camera.