(5905) Johnson

B. Warner, Colorado Springs, CO; P. Pravec and P. Kusnirak, Ondrejov Observatory; D. Pray, Coventry, RI; A. Galad and S. Gajdos, Modra Observatory; and P. Brown and Z. Krzeminski, Department of Physics and Astronomy, University of Western Ontario, report that photometric observations obtained during 2005 Apr. 1-11 show that (5905) is a binary system with an orbital period of 21.78 hr. The primary rotates with a period of 3.783 hr, and its lightcurve amplitude of 0.11 mag is indicative of a nearly spheroidal shape. Mutual events 0.15-0.18 mag deep indicate a secondary-to-primary mean-diameter ratio of 0.4.