Yú Xǐ 虞喜 (281–356), zì Zhòngníng 仲寧, native of Yúyáo 餘姚 in Kuàijī 會稽. His biography stands in Jìn shū 91 (列傳 61, Rúlín). A senior scholar of the Eastern Jìn, he was repeatedly summoned to court under Jìn Yuándì 晉元帝 (r. 317–323), Míngdì 明帝 (r. 323–325), and Chéngdì 成帝 (r. 325–342) — eventually accepting appointment as Tàicháng yuánwài láng 太常員外郎 but retiring to private scholarship in Yúyáo. His astronomical work Āntiān lùn 安天論 announces the precession of the equinoxes (suìchā 歲差) at a rate of 1° per 50 years — the first systematic statement of the phenomenon in China, ahead of subsequent and more precise calculations by Zǔ Chōngzhī 祖沖之 (429–500). He is also the credited author of the philological-and-historical miscellany Zhìlín / Zhìlín xīnshū 志林新書 in 30 juàn (KR3l0156), a foundational biji miscellany now lost but heavily preserved in Péi Sōngzhī’s Sānguó zhì commentary. His ritual and philological writings are repeatedly cited in the Liù Cháo and Táng commentary traditions.
He has no CBDB id assigned in the current dump (CBDB coverage of pre-Táng figures is patchy).