CBET 4893 on (1626) SADEYA

V. Benishek, Belgrade Astronomical Observatory; P. Pravec, Ondrejov Observatory; A. Marchini, R. Papini, and F. Salvaggio, Dipartimento di Scienze Fisiche, Della Terra e Dell’Ambiente, University of Siena; V. Chiorny, Kharkiv Observatory; and M. Husarik, Skalnate Pleso Observatory, report that photometric observations taken with a 0.35-m telescope at the Sopot Observatory in Serbia, a 0.30-m telescope at the Astronomical
Observatory of the University of Siena, a 0.70-m telescope at the Chuguev station of the Kharkiv Observatory in Ukraine, and a 0.61-m telescope at the Skalnate Pleso Observatory during Aug. 1-Nov. 1 reveal that minor planet (1626) is a binary system with an orbital period of 51.3 +/- 0.2 hr. The primary shows a period of 3.4202 +/- 0.0002 hr and has a lightcurve amplitude of 0.16 mag at solar phase 19 degrees, suggesting a nearly
spheroidal shape. Mutual eclipse/occultation events that were 0.07 to 0.10 magnitude deep during Aug. 1-6 indicated a secondary-to-primary mean-diameter ratio of 0.26 +/- 0.02. The events became partial and shallower with depth 0.04-0.05 magnitude during Aug. 16-22 and they disappeared by Sept. 3, indicating that the binary system moved out of eclipse/occultation geometry wrt the Sun and Earth.