SURFACE BRIGHTNESS FLUCTUATION DISTANCES TO NGC-4494 AND NGC-4565 AND THE VIRGOCENTRIC INFALL

The distances to NGC 4565 and NGC 4494 have been measured using the surface brightness fluctuation method in the V band. By adopting a fluctuation magnitude M(V)=+1.0, we have determined a distance modulus of 30.88(-0.26)(+0.31) (d= 15.0(-1.7)(+2.3) Mpc) for NGC 4494, and a distance of 30.08 +/- 0.07 (10.4(-0.3)(+0.4) Mpc) for NGC 4565. Both NGC 4494 and the bulge of NGC 4565 possess very similar colors, so that it is unlikely that differences in stellar population strongly affect these distance measurements. Previous studies of these two galaxies had suggested that they are both members of the Coma I group. Our measurements are incompatible with this hypothesis, but are in good agreement with Virgocentric infall models, which demonstrate that the difference in distances for NGC 4494 and NGC 4565 is probably due to the ''triple-value ambiguity'' in the Virgocentric infall pattern.