Electronic Telegram No. 5060 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 (3912) TROJA V. Benishek, Belgrade Astronomical Observatory; P. Pravec, Ondrejov Observatory; and R. Durkee, Shed of Science South Observatory, Pontotoc, TX, U.S.A., report that photometric observations taken with a 0.35-m telescope at the Sopot Observatory in Serbia and a 0.50-m telescope at the Shed of Science South Observatory during Sept. 7-Oct. 8 reveal that minor planet (3912) is a binary system with an orbital period of 17.371 +/- 0.003 hr. The primary shows a period of 3.65938 +/- 0.00007 hr and has a lightcurve amplitude of 0.18 magnitude at solar phases 1-8 degrees, suggesting a nearly spheroidal shape. Mutual eclipse/occultation events that are 0.11 to 0.14 magnitude deep indicate a secondary-to-primary mean-diameter ratio of 0.33 +/- 0.02. The secondary appears synchronous and has a light-curve amplitude (in the combined primary-plus-secondary light curve) of 0.04 mag, suggesting a moderately elongated shape with an equatorial-axis ratio of 1.4 +/- 0.2. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2021 CBAT 2021 October 22 (CBET 5060) Daniel W. E. Green