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An Ultraviolet Spectrometer for the Rosetta Orbiter

Comet 46P/Wirtanen

Periodic comet Wirtanen was discovered in 1948 by Carl Wirtanen of Lick Observatory in the course of a stellar proper motion survey. The plate on which the discovery was made was taken on 1948 January 15, about a month and a half after the comet had passed perihelion, at which time it was about 16th magnitude. Pre-discovery plates are known which provide positions of the comet from the beginning of December 1947. Within a month after discovery, the comet was determined to be short-periodic. A moderately close approach to Jupiter in April 1972 reduced the perihelion distance to 1.26 AU and the perihelion distance will remain well below 1.5 AU until the mid 21st century. Long-term integrations show that, other than during the current period, the perihelion distance is typically between 1.5 AU and 2 AU from the 17th through the 24th century. 46P/Wirtanen belongs to the Jupiter family of comets, all of which have aphelia between 5 and 6 AU, and it has a period of 5.46 years. There have been four other, non-periodic comets also called "Wirtanen", discovered during the period 1947-1956.

Not much was known about 46P/Wirtanen prior to its being selected as the target for the Rosetta mission. Since then a number of studies and observations have been made of this object, the results of which are summarized below.

Physical Data

Orbital Data

The following information comes from the JPL Horizons System and the 1997 Catalogue of Cometary Orbits.

Period 5.46 years (among the shorter periods for
Jupiter-family comets)
Perihelion Distance 1.064 AU
Eccentricity 0.657
Argument of Perihelion 356.3°
Longitude of the Ascending Node 82.2°
Inclination 11.7°
Perihelion Passages 27 Aug 2002
02 Feb 2008
09 Jul 2013 = end of Rosetta mission


Light Curves

Charles Morris (JPL) has compiled individual light curves for each of comet Wirtanen's 1986 and 1991 apparitions, and has also generated a combined light curve for both apparitions.

Additional information and references are also available at Mr. Morris's 46P/Wirtanen web page.

UV Spectra


Lamy, P.L., L. Jorda, H.A. Weaver and M.A. A'Hearn 1998, A&A, 335, L25-L29.

Stern, S.A., J.W. Parker, M.C. Festou, M.F. A'Hearn, P.D. Feldman, G. Schwehm. R. Shulz, J.-L. Bertaux and D.C. Slater 1998, A&A. 335. L30-L36.

Fink, U., M.D. Hicks, R.A. Fevig, and J. Collins 1998, A&A, 335, L37-L45.

Schulz, R., C. Arpigny, J. Manfroid, J.A. Stüwe, G.P. Tozzi, K. Rembor, G. Cremonese, and S. Peschke 1998, A&A, 335, L46-L49.

Farnham, T.L., and D.G. Schleicher 1998, A&A, 335, L50-L55.

Jockers, K., T. Credner and T. Bonev 1998, A&A, 335, L56-L59.