Electronic Telegram No. 1254 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://www.cfa.harvard.edu/iau/cbat.html (153591) 2001 SN_263 M. C. Nolan, E. S. Howell, Arecibo Observatory; L. A. M. Benner, S. J. Ostro, and J. D. Giorgini, Jet Propulsion Laboratory; M. W. Busch, California Institute of Technology; L. M. Carter and R. F. Anderson, Smithsonian Institution; C. Magri, University of Maine; D. B. Campbell and J. L. Margot, Cornell University; and R. Vervack, Johns Hopkins University, report that Arecibo radar delay-Doppler images (2380 MHz, 12.6 cm) obtained on 2008 Feb. 12 show that minor planet (153591) is a triple system. Based on range extents at 75-m resolution, preliminary estimates of average diameters are 2 km, 1 km, and 400 m for the three components. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2008 CBAT 2008 February 12 (CBET 1254) Daniel W. E. Green