publication 18-January-2019 20:33:11

Determination of the light curve of the Rosetta target asteroid (2867) Steins by the OSIRIS cameras onboard Rosetta

Publication date: 04 January 2007

Authors: K├╝ppers, M. et al.

Journal: Astronomy and Astrophysics
Volume: 462
Issue: 1
Page: L13-L16
Year: 2007

Copyright: ESO

Context: In 2004 asteroid (2867) Steins has been selected as a flyby target for the Rosetta mission. Determination of its spin period and the orientation of its rotation axis are essential for optimization of the flyby planning.

Aims: Measurement of the rotation period and light curve of asteroid (2867) Steins at a phase angle larger than achievable from ground based observations, providing a high quality data set to contribute to the determination of the orientation of the spin axis and of the pole direction.

Methods: On March 11, 2006, asteroid (2867) Steins was observed continuously for 24 h with the scientific camera system OSIRIS onboard Rosetta. The phase angle was 41.7 degrees, larger than the maximum phase angle of 30 degrees when Steins is observed from Earth. A total of 238 images, covering four rotation periods without interruption, were acquired.

Results: The light curve of (2867) Steins is double peaked with an amplitude of 0.23 mag. The rotation period is 6.052 +- 0.007 h. The continuous observations over four rotation periods exclude the possibility of period ambiguities. There is no indication of deviation from a principal axis rotation state. Assuming a slope parameter of G = 0.15, the absolute visual magnitude of Steins is 13.05 +/- 0.03.

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Last Update: 05 September 2008

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