Electronic Telegram No. 5042 Central Bureau for Astronomical Telegrams Mailing address: Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network (5772) JOHNLAMBERT V. Benishek, Belgrade Astronomical Observatory; and P. Pravec, Ondrejov Observatory, report that photometric observations taken with a 0.35-m telescope at the Sopot Observatory in Serbia during Aug. 8-Sept. 12 reveal that minor planet (5772) is a binary system with an orbital period of 17.98 +/- 0.01 hr. The primary shows a period of 3.0782 +/- 0.0002 hr and has a lightcurve amplitude of 0.17 magnitude at solar phases 6-9 degrees, suggesting a nearly spheroidal shape. Mutual eclipse/occultation events that are 0.05 magnitude deep indicate a lower limit on the secondary-to-primary mean-diameter ratio of 0.22. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2021 CBAT 2021 September 19 (CBET 5042) Daniel W. E. Green