ASTRONOMY AND ASTROPHYSICS H 2 O + , CO + , and dust in Comet P / Swift - Tuttle ?

Comet P/Swift-Tuttle was observed in the light of H2O, CO+ and continuum with the 2-m telescope of the Bulgarian National Astronomical Observatory (BNAO) on Nov. 25, 1992. We present column density maps of the H2O and CO+ ions and a map of the product of filling factor, geometrical albedo, and phase function. The H2O ions are more concentrated toward the nucleus than CO+. The ion distributions are in close agreement with magnetohydrodynamic models including photochemistry of H2O, CO+ and their parents. The color of a spiral dust jet present in the continuum image was redder than the color of the ambient dust. The observations demonstrate the similarity between comets P/Halley and P/Swift-Tuttle.