Electronic Telegram No. 5537
Central Bureau for Astronomical Telegrams
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(496869) 2000 QU_7
     P. Pravec, K. Hornoch, P. Kusnirak, H. Kucakova, P. Fatka, and A. Galad,
Ondrejov Observatory; and J. de Leon, Instituto de Astrofisica de Canarias,
report that photometric observations taken with a 1.54-m telescope at the
La Silla station of the European Southern Observatory and a 0.65-m telescope
at Ondrejov Observatory during Feb. 18-Mar. 28 reveal that the Apollo-type
minor planet (496869) is a binary system with an orbital period of 12.58 +/-
0.02 hr.  The primary has a period of 2.881 +/- 0.001 hr and a lightcurve
amplitude of 0.06 magnitude at solar phases 3-11 degrees, suggesting a nearly
spheroidal shape.  Mutual eclipse/occultation events that are 0.17 magnitude
deep indicate a secondary-to-primary mean-diameter ratio of 0.41 +/- 0.02.
The system's mean absolute magnitude is H = 18.28 +/- 0.05 with a phase-
relation slope parameter G = 0.28 +/- 0.05.  The color index in the Johnson-
Cousins photometric system is (V - R) = 0.426 +/- 0.011.  Spectroscopic
observations taken with the OSIRIS instrument on the 10.4-m Gran Telescopio
Canarias at La Palma on Feb. 28 lead to a classification as an S-type minor
planet.  The photometric observations were taken in the framework of their
NEOSource project, supported by the "Praemium Academiae" grant from the
Academy of Sciences of the Czech Republic.  Follow-up observations taken
during the rest of the current apparition of the minor planet are encouraged,
to improve the characterization of the binary system.


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2025 April 4                     (CBET 5537)              Daniel W. E. Green