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

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 46.5444 𝑠 𝛿 𝑝 =+26° 48 ′ 56.706′′ 𝜃= 122°.912729244 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

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