Electronic Telegram No. 5748
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
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(99918) 1998 SQ_2
     R. Durkee, Shed of Science South Observatory, Pontotoc, TX, USA; P.
Pravec and P. Kusnirak, Ondrejov Observatory; V. Benishek, Belgrade
Astronomical Observatory; A. Leroy, Uranoscope de l'Ile de France,
Gretz-Armainvilliers, France; S. Bouley, Geosciences Paris-Saclay Laboratory,
CNRS, Universite Paris-Saclay; and A. Rajaonarivelo, Observatory of Besely,
Ecole du Monde, Madagascar, report that photometric observations taken with a
0.50-m telescope at the Shed of Science South Observatory, a 0.35-m telescope
at the Sopot Observatory in Serbia, and a 0.36-m telescope at Ecole du Monde
Besely in Madagascar during July 25-Sept. 10 reveal that the main-belt
asteroid (99918) is a binary system with an orbital period of 36.09 +/- 0.04 
hr.  The primary shows a period of 3.6815 +/- 0.0004 hr and has a lightcurve 
amplitude of 0.16 magnitude at solar phases 8-14 degrees, suggesting a nearly 
spheroidal shape.  Mutual eclipse/occultation events that are 0.14 magnitude 
deep indicate a lower limit on the secondary-to-primary mean-diameter ratio 
of 0.37.


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                         (C) Copyright 2026 CBAT
2026 September 23                (CBET 5748)              Daniel W. E. Green