Electronic Telegram No. 5533
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
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(6809) SAKUMA
[Editor's note:  this CBET replaces CBET 5532.]
     D. Pray, Sugarloaf Mountain Observatory, South Deerfield, MA, U.S.A.;
P. Pravec, K. Hornoch, K. Honkova, H. Kucakova, and P. Kusnirak, Ondrejov
Observatory; and R. Durkee, Shed of Science South Observatory, Pontotoc, TX,
U.S.A., report that photometric observations taken with a 0.63-m telescope at
the Sugarloaf Mountain Observatory, a 0.65-m telescope at Ondrejov
Observatory, and a 0.50-m telescope at the Shed of Science South Observatory
during Jan. 20-Mar. 7 reveal that minor planet (6809) is a binary system with
an orbital period of 22.792 +/- 0.005 hr.  The primary has a period of 2.57497
+/- 0.00004 hr and a lightcurve amplitude of 0.10 magnitude at solar phases
3-16 degrees, suggesting a nearly spheroidal shape.  Mutual eclipse/
occultation events that are 0.07 magnitude deep indicate a lower limit on the
secondary-to-primary mean-diameter ratio of 0.26.  The system's mean absolute
magnitude in the Cousins R photometric system H_R = 13.22 +/- 0.08, assuming a
phase-relation slope parameter G = 0.24 +/- 0.11.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2025 CBAT
2025 April 1                     (CBET 5533)              Daniel W. E. Green