Electronic Telegram No. 430
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


(1139) ATAMI
     F. Manzini, Sozzago, Italy; R. Behrend, Geneva Observatory; A.
Klotz, Telescope a Action Rapide pour les Objets Transitoires,
Haute-Provence Observatory, France; S. Ostro, L. Benner, and J.
Giorgini, Jet Propulsion Laboratory; M. Nolan and A. Hine, Arecibo
Observatory; J.-L. Margot, Cornell University; C. Magri, University
of Maine, Farmington; M. Shepard, Bloomsburg University of
Pennsylvania; and R. Roy, F. Colas, P. Antonini, P. Paakkonen, L.
Bernasconi, A. Leroy, A. Oksanen, R. Crippa, R. Poncy, S. Charbonnel,
D. Starkey, J. Coloma, C. Cavadore, E. Barbotin, J.-M. Llapasset, G.
Farroni, and R. Koff, on behalf of the CdR-CdL ("Courbes de Rotation
de Asteroides et de Cometes" and "Courbes de Luminosite d'Etoiles
Variables Regulieres") project, report that photometric observations
of the minor planet (1139), obtained between 2005 Aug. 31 and Nov.
6, show sharp attenuations up to 0.7 mag, characteristic of mutual
events in a binary system, at both minima of a regular-appearing
light curve with amplitude 0.40 mag.  The sequence of lightcurves
and a preliminary model suggest that the system is fully synchronized
with a period of 27.45 hours.  Arecibo echo spectra obtained during
2005 Oct. 28-30 confirm the system's binary nature and, given the
optical results, constrain the components to have greatest dimensions
of at least 5 and 6 km and a maximum separation of at least 15 km.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2006 CBAT
2006 March 14                    (CBET 430)               Daniel W. E. Green