Electronic Telegram No. 617 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) CBAT@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/iau/cbat.html (2754) EFIMOV D. Pray, Carbuncle Hill Observatory, Greene, RI; P. Pravec, Ondrejov Observatory; M. Pikler and M. Husarik, Skalnate Pleso Observatory; R. Stephens, Goat Mountain Astronomical Research Station, Yucca Valley, CA; G. Masi, Bellatrix Observatory, Ceccano, Italy; R. Durkee, Minneapolis, MN; and R. Goncalves, Linhaceira, Tomar, Portugal, report that photometric observations obtained during Aug. 14-Sept. 1 reveal that minor planet (2754) is a binary system with an orbital period of 14.765 +/- 0.01 hours. The primary rotates with a period of 2.4497 +/- 0.0002 hours, and it has a lightcurve amplitude of 0.15 mag. Mutual eclipse/occultation events that are 0.04-0.09 mag deep indicate a secondary-to-primary mean-diameter ratio of 0.20 +/- 0.03. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2006 CBAT 2006 September 4 (CBET 617) Daniel W. E. Green