Galaxy NGC 4569 is located at 1.7 degrees (0.32 R_vir) north-east of the core of the Virgo cluster M 87. Contours indicate the distribution of the X-ray gas as derived from ROSAT observations (Böhringer et al. 1994). The CFHT MegaCam continuum-subtracted Hα+[NII] image of the galaxy, smoothed with a 5 × 5 median filter and masked from the emission of foreground stars (see Sect. 3), is magnified by a factor of 6 to emphasise the orientation of the tail of ionized gas with respect to the position of the galaxy within the cluster.