Electronic Telegram No. 5752
Central Bureau for Astronomical Telegrams
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(175189) 2005 EC_224
     P. Pravec, P. Kusnirak, K. Hornoch, H. Kucakova, P. Fatka, and A. Galad, 
Ondrejov Observatory; K. Ergashev and O. Burkhonov, Ulugh Beg Astronomical 
Institute, Tashkent, Uzbekistan; and M. Lazzarin, A. Farina, and P. Ochner, 
University of Padova, report that photometric observations taken with a 1.54-m 
telescope at the La Silla station of the European Southern Observatory and a 
1.5-m telescope at Maidanak Observatory in Uzbekistan during July 9-Sept. 4 
reveal that the Amor-type minor planet (175189) is a binary system with an 
orbital period of 26.45 +/- 0.03 hr.  The primary has a period of 2.506 +/- 
0.003 hr and a lightcurve amplitude of 0.08 magnitude at solar phases 3-26 
degrees, suggesting a nearly spheroidal shape.  Mutual eclipse/occultation 
events that are 0.20-0.38 magnitude deep indicate a lower limit on the 
secondary-to-primary mean-diameter ratio of 0.45.  The system's mean absolute 
magnitude is H = 18.44 +/- 0.13, assuming a phase-relation slope parameter
G = 0.24 +/- 0.11.  The color index in the Johnson-Cousins photometric system 
is (V - R) = +0.422 +/- 0.011.  Visible spectroscopic observations that were 
taken with the 1.82-m Copernico telescope at Asiago Observatory on Aug. 15-16 
show that it is a Q-type minor planet, lying close to the Sq/Q boundary.  
These observations were taken in the framework of the NEOPOPS project that is 
funded by a programme of the European Union implemented by ESA (agreement No. 
4000147191/25/D/MRP).  Follow-up observations taken during the rest of the 
current apparition of this minor planet are encouraged, to improve the 
characterization of the binary system.


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2026 September 28                (CBET 5752)              Daniel W. E. Green