Study of star extinction beyond comet P/Halley

By studying star extinction behind comet P/Halley caused by dust grains, it is possible to identify structures in the dust environment when the extinction does not follow ther−2 profile with radial distance from the nucleus. This has been done with CCD images taken from Catania Observatory on April 23, 1986. The result of the study confirms the presence of two dust jets seen also with images taken with narrow band (cont 685 nm) filters looking only at solar light reflected by dust particles.