Observation of Stars with An Astrolabe And A Meridian Circle

In this paper, the main sources of the errors in a meridian catalog, the characteristics of the equal altitude observation and the shortages of an equal altitude catalog are described. It is emphatically poinled out that the equal altitude observation system is very useful to the comparison of one meridian catalog with, another. It is especially discussed that when stars are observed with a meridian circle and an astrolabe, some constants remaining to be determined can be determined and the reliability of some measured values may be examined, thereby benefiting the raise of the efficiency of the drawing-up of a catalog and the improvement of the accuracy of it.