value quality siderealorsynodic author ref method 15.5490 2 Synodic Waszczak 2015AJ....150...75W Lightcurve 15.5560 2- Synodic Erasmus 2020ApJS..247...13E Lightcurve 15.5570 2 Sidereal Durech 2018A&A...617A..57D Model