1995A&A...297L..17O

We present results from post-perihelion CCD observations of 109P/Swift-Tuttle when it was at a heliocentric distance of 5.3AU. From inspection of the image profiles, contamination from the coma is estimated to be 14%, and thus direct detection of the nucleus was achieved. From the apparent magnitude we deduce a mean effective radius of r_e=11.8km if an albedo of 4% is assumed. An upper mass limit of 7x10¹⁸g is obtained if we assume a density of 1g/cm³. We discuss the extent of active areas on the nucleus of 109P/Swift-Tuttle and estimate that ∼3% of the surface is active.