The National Time Service Center (NTSC) of the Chinese Academy of Sciences (CAS), formerly known as the Shaanxi Astronomical Observatory, is the comprehensive research institute of China which specializes in fundamental research and application study of time and frequency, and satellite precise positioning technology. Established in 1966, NTSC undertakes the task to generate, maintain and transmit the national standard of time (Beijing Time), and operates the long and short wave time service system. It also undertakes important tasks related to time and frequency, navigation and positioning in major national science and technology projects. NTSC is among one of the first batch of scientific research institutions to recruit postgraduates upon the approval by the State Council in 1981.

NTSC has one post-doctoral station in astronomy, three doctorate degree awarding units in astrometry and astromechanics, testing and metrology technology and instruments and communication and information system. There are four master degrees awarding units in astrometry and astromechanics, precision measurement physics, testing and measurement technology and instruments, communication and information system and one professional master degree awarding unit of electronic and Communication Engineering. At present, more than 150 students study at NTSC.

Resting on national major scientific and technological projects such as "National Major Scientific and Technological Infrastructure", "BeiDou Satellite Navigation Major Project", "Manned Spaceflight" and "National Time and Frequency System", two key laboratories of the Chinese Academy of Sciences and over ten advanced laboratories, students are encouraged to join, widen their horizon and conduct innovative research in multiple fields. Under the careful guidance of supervisors, NTSC trained a number of young talents in the field of time frequency and satellite navigation. In addition to some excellent graduates staying in NTSC, most of others find their job in universities, research institutes and well-known enterprises.

NTSC is located in Lintong District of Xi'an where two world-famous national 5A scenic spots are located. Every two postgraduate students live in one studio with air conditioning (free accommodation). It also offers postgraduate office, outdoor basketball court, artificial turf football field and indoor sports complex, which provides favorable conditions for study, scientific research, academic exchange and physical exercise.

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 people at work, which ensures that postgraduates "study and research at ease" in terms of funds.

Over the past 50 years, NTSC has formed a relatively sound and complete discipline chain in the field of time and frequency, and has close cooperation with many well-known universities and research institutions at home and abroad. It is an ideal place for further study in the field of time and frequency, satellite navigation and other research areas.