原子时标TA（NIM）是一个独立时标,其频率由NIM5铯喷泉基准驾驭。产生时标的主钟是一台主动型氢原子钟,铯喷泉基准定期对其测量和校准。时标算法通过预估氢钟将来的频率,补偿过去预估频率与校准频率之差,并评估无校准数据期间的氢钟频率,最终尽可能实现TA（NIM）的频率与NIM5铯喷泉基准保持一致。2007年8月,TA（NIM）开始试运行,2008年6月正式运行。1年多来的数据分析表明,TA(NIM)运行连续可靠,与TAI间的时间稳定度(5天)达到1.2 ns,相对频差为2.0×10^-15。

TA (NIM) is an independent atomic time scale. It is steered by a primary frequency standard that is NIM5 cesium fountain clock. The reference clock of TA (NIM) is an active hydrogen maser, which is measured and calibrated by the primary frequency standard periodically. A time scale algorithm can predict future frequency of the hydrogen maser, compensate frequency difference between the prediction and the calibration, and estimate the maser’s frequency when NIM5 fountain is not operational, in order to keep the frequency of TA(NIM) the same as the frequency of NIM5 fountain as much as possible. TA(NIM) began test run from August, 2007 and started to run formally from June, 2008. Data in recent more than one year show that TA(NIM) runs continuously, its time deviation (5 days) relative to TAI is 1.2 ns,and its frequency offset relative to TAI is 2.0×10^-15.