CCD photometry of active Centaur 166P/2001 T4 (NEAT)

Abstract

To study the secular evolution of the activity of Centaur 166P/2001 T4 (Near Earth Asteroid Tracking, NEAT) and its physical properties, we present the results of optical observations of the Centaur taken on 2009 March 29 with the Keck 10-m telescope located atop Mauna Kea, Hawaii. It was still active at rh = 11.9 au post-perihelion. An upper limit of the nucleus radius of aN < 14.32 km is derived. The colour index is B - R = 1.59 ± 0.05. The Afρ value is measured to be 288 ± 19 cm and the corresponding dust production rate is 252 kg s-1. Finally, a possible mechanism of activity is discussed.