value	quality	siderealorsynodic	author	ref	method
21.1500	2	Sidereal	Durech	2019A&A...631A...2D	Model
21.1500	2	Sidereal	Durech	2023A&A...675A..24D	Model
21.1500	2	Synodic	Bembrick	2007MPBu...34...67B	Lightcurve
21.1526	2	Synodic	Pal	2020ApJS..247...26P	Lightcurve