A Method for Determining the Errors Caused When the Lower Latitude Meridian Circle is Put in Different Directions

In order to obtain the highly repeated accuracy which is needed when the lower latitude meridian circle(LLMC)is put in different directions and to ensure that the meridian direction of the instrument should be strictly perpendicular to the prime vertical,a system consisting of a collimator and a cubic reflector is used to determine and correct the errors produced when the LLMC is put in different directions during the observation of a star,thereby making the repeated accuracy better than ±0.01.