The 2000 Rosetta asteroid targets observational campaign: 140 Siwa and 4979 Otawara

Research areas:
Year:
2001
Authors:
Journal:
ASTRONOMY & ASTROPHYSICS
Volume:
379
Number:
2
Pages:
660-663
Month:
November
ISSN:
0004-6361
BibTex:
Abstract:
Photometric and spectroscopic observations of 140 Siwa and 4979 Otawara,
targets of the Rosetta mission, have been carried out at the European
Southern Observatory (ESO, Chile). The complete lightcurves in V and R
of both asteroids and the Siwa spectrum in the range 0.95-2.52 mum have
been obtained. We determined the precise synodic rotational period of
140 Siwa (18.495 h +/- 0.005 h) and we confirmed the synodic rotational
period of 4979 Otawara (2.707 h +/- 0.005 h). The phase function has
been obtained for both asteroids, allowing the determination of the H-V
and G(V) parameters: for 4979 Otawara H-V = 14.62 mag, G(V) = 0.34; for
140 Siwa H-V = 8.34 mag, G(V) = 0.17. The near infrared spectrum of Siwa
does not show any spectral feature, which is consistent with a C/P type
object.