Research Note

433 Eros – comparison of lightcurve extrema from 1901–1931 with the present rotation state

Astronomical Institute, Charles University in Prague, V Holešovičkách 2, 18000 Prague, Czech Republic e-mail: durech@sirrah.troja.mff.cuni.cz

Received: 30 October 2004
Accepted: 17 November 2004

Abstract

The NEAR/Shoemaker space probe determined accurately the rotation period and spin axis direction of asteroid Eros (Konopliv et al. 2002, Icarus, 160, 289). The synthetic lightcurves of Eros derived from its actual rotation state and known shape are compared with the times of lightcurve extrema determined visually, photographically or photometrically during the oppositions in years 1901–1931. The results show that the actual rotation period derived from the NEAR/Shoemaker observations corresponds to the old data (about 290 individual points). The search for any possible acceleration or deceleration of Eros's rotation (caused by, e.g., the YORP effect) was negative due to large errors in the epochs of lightcurve extrema. Nevertheless, the data put a limit on the change of Eros's rotation angular velocity that cannot be greater than ~. The formal fit to the data gives the deceleration of Eros's rotation , which is in agreement with the theoretical value derived by Čapek & Vokrouhlický (2004, Icarus, 172, 526).