value quality siderealorsynodic author ref method 6.9430 2 Synodic Behrend LCDB Lightcurve 6.9450 2- Synodic Polakis 2019MPBu...46..400P Lightcurve 6.9490 2 Synodic Benishek 2014MPBu...41..263B Lightcurve