Electronic Telegram No. 910 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 (1338) DUPONTA S. Gajdos, L. Kornos, J. Vilagi, and A. Galad, Modra Observatory; P. Pravec, Ondrejov Observatory; R. Stephens, Goat Mountain Astronomical Research Station, Yucca Valley, CA; V. Reddy, Department of Earth System Science and Policy, University of North Dakota, Grand Forks; R. Dyvig, Quinn, SD; D. Higgins, Canberra, Australia; J. Oey, Leura, N.S.W., Australia; and D. Pray, Carbuncle Hill Observatory, Greene, RI, report that photometric observations obtained during Mar. 6-26 reveal that minor planet (1338) is a binary system with an orbital period of 17.57 +/- 0.01 hr. The primary shows a period of 3.85453 +/- 0.00009 hr, and it has a lightcurve amplitude of 0.23 mag. Mutual eclipse/occultation events that are 0.06- to 0.12-mag deep indicate a secondary-to-primary mean-diameter ratio of 0.23 +/- 0.02. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2007 CBAT 2007 March 27 (CBET 910) Daniel W. E. Green