Observations of occulation of HIP 66446 by (423) Diotima on 2001 March 15 from India - Detection of a companion to the star

Abstract

Observations of the occulation of the star HIP 66446 by (423) Diotima on 2001 March 15 made by the team at the Vainu Bappu Observatory and three mobile teams at Ganeshgudi, Londa and the CES Field Research Station at Sirsi are presented. We make a preliminary estimate of 186 km x 149 km for the projected size of the asteroid. The immersion and emersion events occurred in two stages revealing the binary nature of the star for the first time. The derived integrated brightness ratio of the stars from the two step immersion and the emersion events is found to be 1.33 ± 0.27. The projected separation between the two components along the track, i.e. along the direction 115o from North, is found to be 28 km or 0.018 ± 0.002 arcsec.