Title：Tie of Celestial Reference Frames in the Age of Microarcsecond Precision

Speaker：Niu Liu  (NJU)

Special Time：3:00 pm Oct. 13th (Friday)

Tencent Meeting：429-1540-0486 password: 6360

Location: Lecture Hall, 3rd floor

Abstract：

The celestial reference frame is a cornerstone of fundamental astronomy, serving diverse applications, from geodesy to Earth’s rotational studies and from measuring Galactic proper motions to spacecraft navigation. The third generation of the International Celestial Reference Frame (ICRF3), the Gaia Celestial Reference Frame (Gaia-CRF3), and the planetary ephemeris reference frame realize the International Celestial Reference System (ICRS) in different ways, all achieving an accuracy level approaching microarcseconds. Practically, the challenge now lies in properly connecting these distinct reference frames while preserving their remarkable precision, enabling the construction of the next-generation multifrequency celestial reference frame. To this end, several key questions need to be addressed, such as understanding and modeling of systematics in each frame, the careful selection of frame-tie sources, and the proposal of frame-tie method, in addition to dedicated high-quality observations. In this talk, I will introduce recent progresses made in this field, with a primary focus on the tie between the Gaia-CRF and ICRF, offering insights into the future of celestial reference frames and their indispensable role in advancing astronomical research.

CV：

Dr. Niu Liu is an Assistant Professor at NanjingUniversity. He obtained his Bachelor's degree from Nanjing University in 2015and pursued a joint training program at the Paris Observatory in 2017. In 2020,he completed his Ph.D. and, in the same year, was awarded the "Yuxiu YoungScholar" program fellowship to start his postdoctoral research at NanjingUniversity. In 2021, he received the Outstanding Ph.D. Thesis Award fromJiangsu Province.

His primary research interests include theastronomical reference system, VLBI astrometry, and space astrometry.Currently, his research is focused on establishing the connection betweenGaia-CRF and ICRF and investigating Gaia's parallax bias. He has authored over20 SCI papers and is currently leading and contributing to several NSFC projects. Additionally, he serves as a reviewer for A&A, Acta AstronomicaSinica, and Frontiers Astronomy and Space Sciences.