Hubble Space Telescope imaging of globular clusters in the edge-on spiral galaxies NGC 4565 and NGC 5907

We present a study of the globular cluster systems of two edge-on spiral ga laxies, NGC 4565 and NGC 5907, from WFPC2 images in the F450W and F814W fil ters. The globular cluster systems of both galaxies appear to be similar to the Galactic globular cluster system. In particular, we derive total numbe rs of globular clusters of N-GC(4565) = 204 +/- 38(-53)(+87) and N-GC(5907) = 170 +/- 41(-72)(+47) (where the first are statistical, the second potent ial systematic errors) for NGC 4565 and NGC 5907, respectively. This determ ination is based on a comparison with the Milky Way system, for which we ad opt a total number of globular clusters of 180 +/- 20. The specific frequen cy of both galaxies is S-N similar or equal to 0.6, indistinguishable from the value for the Milky Way. The similarity in the globular cluster systems of the two galaxies is noteworthy, since they have significantly different thick disks and bulge-to-disk ratios. This would suggest that these two co mponents do not play a major role in the building up of a globular cluster system around late-type galaxies.