DPS 2001 meeting, November 2001
Session 43. Comet C/2001 A2 (LINEAR)
Oral, Chair: M. A'Hearn, Friday, November 30, 2001, 11:30am-12:30pm, Regency E

## [43.04] Observations of the 557 GHz Line of Water in Comet C/2001 A2 (LINEAR) with the Odin Satellite

N. Biver (ESA, ESTEC & Obs. de Paris), A. Lecacheux, J. Crovisier, D. Bockelée-Morvan (Obs. de Paris), H. Rickman, C.I. Lagerkvist (Uppsala Astronomical Observatory), A. Winnberg (Onsala Space Observatory), ODIN Team

Odin is a small astronomical/aeronomical satellite which was launched in February 2001. One of its capacities is the observation of the 110--101 line of water at 557 GHz with a high spectral resolution (corresponding to 80 m s-1) and a spatial resolution of 2 arcmin.

During its commissioning phase, Odin observed comet C/2001 A2 (LINEAR) several times in April and from June 20 until July 9, 2001. From a preliminary analysis, 10 \times 10 arcmin mapping of the 557 GHz water line on July 1.5--2.4 UTC shows that the H2O coma is elongated along the comet-Sun line. The line shape is asymmetric, which may be attributed to self-absorption in the foreground of the coma. The line width indicates a H2O outflow velocity of 0.7 km s-1. The integrated line intensity peaks at 12 K km s-1 on the main-beam brightness temperature scale. The corresponding water production rate is estimated at 3.8 \times 1028 molecules s-1 for July 1.7--2.0. The outflow velocity and water production rate agree with independent observations of the 18 cm lines of OH at the Nançay radio telescope.

Odin (http://www.snsb.se/odin/odin.html) is a Swedish-led satellite project funded jointly by SNSB (Sweden), CSA (Canada), Tekes (Finland) and CNES (France), Swedish Space Corporation being the prime contractor.