EDP Sciences
Free access
Volume 414, Number 2, February I 2004
Page(s) 749 - 755
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20031610

A&A 414, 749-755 (2004)
DOI: 10.1051/0004-6361:20031610

Optical observations of Comet 67P/Churyumov-Gerasimenko

M. Weiler1, H. Rauer1 and J. Helbert2

1  Institute of Planetary Research, DLR, Rutherfordstrasse 2, 12489 Berlin, Germany
2  Optical Information Systems and Space Sensor Technologies, DLR, Rutherfordstrasse 2, 12489 Berlin, Germany

(Received 5 August 2003 / Accepted 13 October 2003)

From longslit spectra obtained during the 1996 perihelion passage of Comet 67P/Churyumov-Gerasimenko, a CN production rate of $\rm (1.35 \pm 0.35) \times 10^{25}$ molecules $\rm s^{-1}$ was determined and an upper limit for the $\rm C_3$ production rate of  $1 \times 10^{25}$ molecules $\rm s^{-1}$ was derived. The dust color and dust activity were determined from the continuum light in the spectra. A neutral dust color was determined between 4070 Å and 4600 Å. The CN production rate and the Af $\rho$ parameter, determined to  $\rm (428.2 \pm 59.8)$ cm, were similar to the values of the 1982 perihelion passage, indicating that the comet's activity did not change significantly in recent orbital passages. A first crude estimate of the dust production rate indicates a high dust to gas mass ratio.

R-filter images taken in March 2003 were used to study the dust coma morphology. Two jet structures were seen in the coma; these structures show no variations within the observing period from March 7 to May 30, 2003. The orientation of these stationary structures suggests an inclination of the rotation axis of the nucleus of approximately  $\rm
40^\circ$ with respect to the orbital plane.

Key words: comets: general -- comets: individual: 67P/Churyumov-Gerasimenko

Offprint request: M. Weiler, michael.weiler@dlr.de

© ESO 2004