世界时与地球时转换经验公式的改进与比较

Improvement and Comparison of Empirical Formula for Conversion between Universal Time and Terrestrial Time

针对世界时与地球时的差值△T问题，提出了新的拟合多项式。基于美国海军天文台发布的1657年～2020年间的△T数据，以及IERS（International Earth Rmarionand referencesy stems Service，国际地球自转和参考系服务组织）公报中公布的LS（Leap Seconds，跳秒）数据，在美国NAsA（National Aeronauties and Space Administration，国家航空航天局）经验公式的基础上进行了改进，分别用3次、4次、5次、6次多项式进行拟合。然后，基于最小二乘法得到一组多项式经验公式，可适用于公元纪年、儒略日、简约儒略日以及从J2000．0起算的儒略世纪数等4种时间格式。通过精度计算表明，该组经验公式计算结果与USNO（United States Navy Observatory，美国海军天文台）基准序列的残差不超过±1．29s，与IERS基准序列的残差不超过±0．16s，整体优于NASA经验公式的计算精度。同时还给出了得到更高精度经验公式的拟合方法。

A new fitting polynomial is proposed to calculate the difference between universal time and terrestrial time. The new empirical formula is an improvement of NASA （National Aeronautics and Space Administration） empirical formula expressed in the form of three, four, five and six polynomials to fit and be based on the least square method and the ATtrue values 1656-2020 announced by U. S. Naval Observatory and the data of leap seconds published by IERS （International Earth Rotation and reference systems Service） . The new empirical formula is suitable for Christian era, Julian date, modified Julian date and Julian centuries starting from J2000.0. The differences between the results of the new empirical formula and the ATvalue of USNO （United States Navy Observatory） datum series don＇t exceed ± 1.29 seconds, and that of IERS datum series don＇t exceed ± 0.16 seconds, better than that of NASA empirical formula. Methods to obtain much more accurate empirical formula are also given.