摘要
评述了各种度盘对径改正的方法；用玫瑰系列法对DCMT进行N=180的抽样实验测试，估计DCMT度盘常规读数对径误差为±0．25"。通过对度盘所有对径测试（N=5400）的精度统计特性的分析，得出49°30'、46°40'、43°12'是最优化的玫瑰系列测试组合；此外还论证了当对精度的统计特性的随机性要求不很严格时，在DCMT上实施小玫瑰角系列是可行的，其最优化组合是0°10'、46°40'、50°24'角系列。
The principle of the observations of declination for celestial bodies by meridian circleis quite different from that of right ascension. The right ascension is measured by thetransit time, while the declination measurement is made by means of star position in fieldof telescope and the readings of graduated circle equipped with a few pairs of microscopes.So, the accuracy for determination of dec1ination is depend on the accuracy of determination of diameter corrections. It is the reason why diameter correction is so important formeridian circle.The classical method is that a few essential lines are determined with high precision,and others are determined related to the essential lines. So, the diameter corrections byclassical method are determined with different precision. A method which permits the determination of all corrections with the same preclsion was expected. It should be symmetric for all circle lines. The Bruns' method, a elementarily symmetric method and late developed methods, such as general symmetric method and rosettes combination method,have better efficiencies and accuracies than nonsymmetric methods.In order to determlne the diameter corrections for the graduated circle (with 5 400 diameters ) of the Danish-Chinese Meridian Circle (DCMT), the scanning micrometers andthe glass circle are introduced, and the comparison on the feasibility and reliability between different methods has been made. According to the comparison, we employed theBenevides method (Rosettes combination method) as our meth0d for determining theDCMT circle diameter corrections' A computati0n with N= 180 diameters for statisticalfluctuation of correction covariance has been obtained. According to the simu1ated computation, the authors find that the most optimum combination is with the three rosettes angles 49°30',46°40' and 43°12',which permits a favorable solution for the corrections. Furthermore, a test observation and the copulation for the diameter correction on DCMT havebeen made. The authors have the conclusion that the effective accuracy of circle lines fordiameters correction is about 0. 25'. It is believed that the method stated above is availablefor the determination of all lines on DCMT.
出处
《陕西天文台台刊》
CSCD
1997年第6期101-106,共6页
Publications of The Shaanxi Astronomical Observatiory
