1. Nanjing University Research Group of Astrometry and Reference System
Research Field
Faculty
Astrometry and catalogue
Galactic structure and kinematics
Astronomical reference systems and frames
Rotation of the Earth
Relativistic fundamental astronomy
PI: Prof. Zhu Zi
Members: Zhang Hong, Wan Xiaosheng,
Xie Yi, Liu Jia-Cheng

2. Researches on fundamental astronomy
Redefinition of the Galactic coordinate system
The limitations and possible misunderstandings in the transformation of the Galactic coordinate system from the FK4 to the ICRS has been pointed out, and the new coordinate system was established using modern all sky surveys.
The resulting parameters for the orientation of the Galactic coordinate system:
𝛼 𝑝 = 12 ℎ 50 𝑚 𝑠
𝛿 𝑝 =+26° 48 ′ ′′
𝜃= 122°
The 2MASS sky distribution which was used to fit the optimal Galactic plane (the X-Y plane of the coordinate system).
Liu J.-C., Zhu Z., & Zhang H., 2011, A&A 516, A16;
Liu J.-C., Zhu Z., & Hu B., 2011, A&A 536, A102

3. Theoretical study of the Galactic aberration
In cooperation with Paris Observatory and Pulkovo Observatory.
For extragalactic sources and ICRF
No Global rotation around the axis toward the Galactic center
No Global rotation if the distribution of sources is uniform
0.1-1 𝜇𝑎𝑠 𝑦𝑟 −1 rotation of the reference frame, about 1𝜇𝑎𝑠 𝑦𝑟 −1 contribution to precession rate
The apparent proper motion of the ICRF2 catalogue.
Liu J.-C., Capitaine N., Lambert S., Malkin Z., & Zhu Z. 2012, A&A 548, A50