IAU CBET nº4517:
(17700) 1953 XU_1 = 1997 GM_40 = 1999 VD_53
D. Pray, Sugarloaf Mountain Observatory, South Deerfield, MA, U.S.A.;
P. Pravec, H. Kucakova, K. Hornoch, and P. Kusnirak, Ondrejov Observatory;
J. Oey, Blue Mountains Observatory, Leura, NSW, Australia; V. Benishek,
Belgrade Astronomical Observatory; A. Aznar, Astronomia Para Todos
Observatories Group, «European Near Earth Asteroids Research (EURONEAR)»,
Spain; and A. L. Comazzi, Instituto de Astrofisica de Andalucia, CSIC,
Spain, report that photometric observations obtained with a 0.50-m
telescope at the Sugarloaf Mountain Observatory, a 0.65-m telescope at the
Ondrejov Observatory, a 0.61-m, a 0.35-m and a 0.31-m telescopes at the
Blue Mountains Observatory, a 0.35-m telescope at the Sopot Observatory in
Serbia, and a 0.90-m telescope at Sierra Nevada Observatory during
Mar. 20-May 10 reveal that minor planet (17700) is a binary system with an
orbital period of 15.49 ± 0.02 hr. The primary shows a period of 3.8382
± 0.0002 hr and has a lightcurve amplitude of 0.13 mag at solar phases
8-15 degrees, suggesting a nearly spheroidal shape. Mutual
eclipse/occultation events that are up to 0.20-magnitude deep indicate a
lower limit on the secondary-to-primary mean-diameter ratio of 0.31.
There occurred two additional 0.14- to 0.18-magnitude-deep attenuations on
Mar. 20 and 25 that were not aligned with the 15.49-hr orbital period,
suggesting presence of a third body in the system. The mean absolute
magnitude of the whole system in the Cousins R photometric system is H_R =
13.98 ± 0.05 with the phase relation slope parameter G = 0.35 ± 0.05.