value	quality	siderealorsynodic	author	ref	method
21.7014	2	Sidereal	Durech	2020A&A...643A..59D	Model
21.7020	2	Sidereal	Durech	2023A&A...675A..24D	Model
21.7540	3	Synodic	Warner	2017MPBu...44..331W	Lightcurve
4.0000		Synodic	Slyusarev	LCDB	Lightcurve