Electronic Telegram No. 5198 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 2005 LW_3 S. P. Naidu, L. A. M. Benner, M. Brozovic, and J. D. Giorgini, Jet Propulsion Laboratory, California Institute of Technology; S. Horiuchi and I. Savill-Brown, Canberra Deep Space Communication Complex, CSIRO; J. Stevens, C. Phillips, and P. Edwards, Australian Telescope National Facility, CSIRO; and E. Kruzins, University of New South Wales, report that Goldstone radar (8560 MHz, 3.5 cm) images obtained on Nov. 23, 24, and 27 (when Delta = 0.008 to 0.03 AU) reveal that the Apollo-type minor planet 2005 LW_3 is a binary system. The maximum range separation between the primary and secondary was observed to be about 4 km. In images with range resolutions of 3.75 m, the visible range extent of the primary is roughly 200 m, suggesting body extents in the line-of-sight direction of around 400 m. The spin period of the primary is roughly 3.6 hr, based on intervals at which the surface features repeat in the images. The visible range extent of the secondary varied between 7-15 pixels, suggesting that it is elongated and has equatorial extents between 50 and 100 meters. Echo power spectra obtained on Nov. 22 and 23, using DSS-43 (7159.45 MHz, 4.2 cm) to transmit and the Australia Telescope Compact Array to receive, also show a narrow spike corresponding to the secondary, superimposed on the broader echo from the primary. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2022 CBAT 2022 December 10 (CBET 5198) Daniel W. E. Green