National Time Service Center (NTSC) of the Chinese Academy of Sciences (CAS), formerly known as Shaanxi Astronomical Observatory, is the only professional research institute of China which specializes in fundamental research and application study of time and frequency. Established in 1966, NTSC provides national standard time calibration for systems such as Beidou and Changhe-2 in China. At the same time, based on the long-term high-precision time and frequency measurement research, NTSC conducts research related to satellite navigation.

NTSC is responsible for determining and maintaining China’s coordinating universal time standard(UTC(NTSC))and Atomic time standard(TA(NTSC). The accuracy and long-term stability of TA(NTSC) and UTC(NTSC) are ranked among top in time laboratories across 80 countries worldwide, playing a crucial role in the determination and maintenance of international atomic time.

Over the past 50 years, NTSC has established a relatively complete time and frequency discipline chain, covering the entire field of time and frequency, from "frequency source" to "timekeeping", "time service", and "time usage". A series of time service systems were successively established, such as The BPL and BPM National time service systems, low-frequency time codes, telephone, network, and communication satellite time service systems, which have provided reliable high-precision time service for many industries and departments in China, including communication, power, transportation, mapping, aerospace, national defense. NTSC successfully completed the time service tasks during all previous satellite and rocket launches of our country, and were repeatedly commended by relevant national departments. It made indispensable and significant contributions to China's national economic construction and social development.

NTSC is one of the first batch of degree-awarding institutions approved by the State Council. It has one post-doctoral station in astronomy, four doctorate degree awarding units in astrometry and celestial mechanics, testing and metrology technology and instruments, communication and information system and electronic information. There are five master degrees awarding units in astrometry and celestial mechanics, precision measurement physics, testing and metrology technology and instruments, communication and information system and electronic information. At present, there are 33 doctoral supervisors, 50 master's supervisors, and more than 210 students study at NTSC.

The postgraduate award system of NTSC consists of state grants, national scholarship, academic scholarships of University of Chinese Academy of Sciences and scholarships of NTSC. Other welfare such as medical service and lunch is the same as those for regular employees, which ensures that postgraduates "study and research at ease" in terms of funds.

Over the years, relied on its close cooperative relationships with numerous renowned universities and research institutions both domestically and internationally, NTSC has become an ideal place for professional research and further studies in fields time and frequency and satellite navigation. Based on the research platform of the institute, supervisors encourage students to participate and provide them with multiple opportunities to broaden their innovative horizons and conduct innovative research. Under the careful guidance, a group of young talents in the fields of time frequency and satellite navigation have been cultivated. Apart from some outstanding graduates who choose to stay and work in NTSC, most of them have found employment in universities, research institutions and well-known enterprises.