Electronic Telegram No. 1881
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)
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(26471) 2000 AS152
     B. D. Warner, Palmer Divide Observatory and Space Science Institute,
Colorado Springs, CO; A. W. Harris, Space Science Institute, La Canada, CA;
and D. Pray, Carbuncle Hill Observatory, West Brookfield, MA, report that
photometric observations obtained during July 13-19 reveal that minor planet
(26471) is a binary system with an orbital period of 1.634 +/- 0.001 days.
The primary shows a period of 2.6866 +/- 0.0002 hr and has a lightcurve
amplitude of 0.22 mag.  Mutual eclipse/occultation events indicate the lower
limit of the secondary-to-primary mean diameter to be 0.38 +/- 0.02.  The
observations for July 19 indicate the possibility that a shadow event, where
the shadow of the secondary transited the primary, was also observed.  If
this is the case, then continued observations at different phase angles may
show an evolution in the combined and separated lightcurves.

     The next two mutual events (primary and secondary, although which is
which is uncertain) should be centered around July 20.978 and 21.795 UT
(+/- 10 min).  The events are approximately 4 hr in duration.



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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2009 CBAT
2009 July 20                     (CBET 1881)              Brian G. Marsden