(1717) Arlon

W. Cooney, J. Gross, and D. Terrell, Sonoita Research Observatory, Sonoita, AZ; P. Pravec and P. Kusnirak, Ondrejov Observatory; D. Pray, Carbuncle Hill Observatory, Greene, RI; Yu. Krugly, Kharkiv Observatory; L. Kornos, J. Vilagi, S. Gajdos, and A. Galad, Modra Observatory; V. Reddy, Department of Space Studies, University of North Dakota, Grand Forks; R. Dyvig, Quinn, SD; S. Nudds, Elginfield Observatory, University of Western Ontario; and Z. Kanuchova, M. Pikler, and M. Husarik, Skalnate Pleso Observatory, report that photometric observations obtained during Feb. 24-Apr. 17 confirm that the system is binary. Mutual events (satellite occultation and eclipse behind the primary, as well as transits of the satellite and its shadow over the primary) were observed to be repeating with a synodic orbital period of 117.0 hr. The two linearly additive components with periods of 5.148 and 18.23 hr (initially reported on CBET 369) are still present, and they are interpreted as rotation lightcurves of the components of the binary system. Depths of the observed attenuations put a lower limit on a secondary-to-primary mean-diameter ratio of 0.5.