W. J. Merline, Southwest Research Institute (SwRI); P. M. Tamblyn, Binary Astronomy and SwRI; C. R. Chapman, D. Nesvorny, and D. D. Durda, SwRI; C. Dumas, JPL; A. D. Storrs, Towson University; L. M. Close, University of Arizona; and F. Menard, Observatoire de Grenoble, report the discovery on July 26.6 UT, on six direct images (two sets of three images taken 20 min apart in time) made with the Hubble Space Telescope (+ ACS/HRC) in the F606W (600-nm broadband) filter, of a satellite of minor planet (22899) 1999 TO_14 (V about 18). The satellite is clearly separated in five of these images but streaked in a sixth due to pointing jitter. Trails of several background stars in successive images indicate that the target object is not a background binary star. On July 26.6545, the satellite was at separation 0".14 (projected separation 170 km) in p.a. 235 deg. Using the average albedo of the Koronis family (about 0.21), to which (22899) belongs, the size of the primary is estimated to be 4.5 km. The brightness difference is about 2.5 mag, giving an estimated diameter of the secondary of about 1.5 km. This then is the smallest main-belt asteroid known to be binary.
International Astronomical Union Circular
- Pub Date:
- October 2003