The Observation of A Star by Making A 180-Degree Rotation of the Horizontal Axis of A Lower-Latitude Meridian Circle

A traditional meridian circle can result in a series of systematic errors,such as the azimuth error,collimation error,level error,error from the flexture of the tube,graduation error,etc.The effects of these errors on the observations should be corrected.In this paper,the method for determining instrumental errors with a traditional meridian circle is compared with that with a lower-latitude meridian circle of which the horizontal axis makes a 180-degree turn when a star is observed.Some of the instrumental errors can be eliminated and some can be determined conveniently if Hie lower-latitude meridian circle is used.Finatly,some characteristics of the lower-latitude meridian circle are discussed.