Comet P/Swift-Tuttle was observed in the light of H2O+, CO+ and contin
uum with the 2-m telescope of the Bulgarian National Astronomical Obse
rvatory (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, geometr
ical albedo, and phase function. The H2O+ ions are more concentrated t
oward the nucleus than CO+. The ion distributions are in close agreeme
nt with magnetohydrodynamic models including photochemistry of H2O+, C
O+ and their parents. The color of a spiral dust jet present in the co
ntinuum image was redder than the color of the ambient dust. The obser
vations demonstrate the similarity between comets P/Halley and P/Swift
-Tuttle.