Electronic Telegram No. 5505
Central Bureau for Astronomical Telegrams
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Prepared using the Tamkin Foundation Computer Network


(3255) THOLEN
     V. Benishek, Belgrade Astronomical Observatory; P. Pravec, Ondrejov
Observatory; M. Husarik, M. Pikler, and G. Cervak, Skalnate Pleso Observatory;
and N. Ruocco, Sorrento, Italy, report that photometric observations taken
with a 0.35-m telescope at the Sopot Observatory in Serbia, a 0.61-m telescope
at the Skalnate Pleso Observatory, and a 0.35-m telescope at Osservatorio
Astronomico Nastro Verde in Italy during 2024 Oct. 19-Nov. 2 reveal that minor
planet (3255) is a binary system with an orbital period of 44.36 +/- 0.07 hr.
The primary shows a period of 2.9461 +/- 0.0003 hr and has a lightcurve
amplitude of 0.16 magnitude at solar phases 24-29 degrees, suggesting a nearly
spheroidal shape.  Mutual eclipse/occultation events that are 0.20 magnitude
deep indicate a lower limit on the secondary-to-primary mean-diameter ratio of
0.45.  The secondary appears synchronous and has a light-curve amplitude (in
the combined primary-plus-secondary light curve) of 0.10 mag, suggesting a
moderately elongated shape with an equatorial-axis ratio of 1.4 +/- 0.1.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2025 CBAT
2025 February 18                 (CBET 5505)              Daniel W. E. Green