 The lightcurve gave a rotation period of hours with a brightness variation of 0.50 in magnitude ().According to the 2015/16 NEOWISE mission results of NASA's space-based Wide-field Infrared Survey Explorer, 
"Geisei" measures 5.21 and 5.23 kilometers in diameter and its surface has an albedo of 0.34 and 0.38, respectively.Preliminary WISE results gave a diameter of 6.582 kilometers and an albedo of 0.275.