Study of Some Problems on Achieving Curvature Corrections

It is quite necessary to study more possible sources of errors, including the curvature corrections before the Lower Latitude Meridian Circle(LLMC) is put into operation in Yunnan Observatory. The fact is that the micrometer previously schemed to be mounted onto the LLMC will be changed in its structure to satisf.y the demands of the LLMC. As far as the LLMC with an attached photon counting micrometer is concerned, three types of curvature corrections should be included during the data reduction. They are the curvature corrections for recorded time, for determined zenith distance when a star passes the prime vertical plane, and for the determined zenith distance when the star crosses the meridian plane. A new solution to handling curvature corrections is presented in this paper by means of Analytic Geometry after a new type of grid for the micrometer is adopted.