  In this third paper of our series on near-IR and optical photometry of
globular cluster systems in early-type galaxies we concentrate on the
photometric results for NGC 5846 and NGC 7192, two group ellipticals, and on a
first comparison between the globular cluster systems investigated so far. In
NGC 5846 the colour-colour diagram shows clear bi-modality in (V-K), which is
confirmed by a KMM test. The mean colour of both peaks were estimated to be
(V-K) =2.57+/-0.06 (blue) and (V-K)=3.18+/-0.06 (red). The situation in NGC
7192 is different, in that the colour-colour diagram gives no evidence for a
distinct second population of globular clusters. Using simulated colour
distributions of globular cluster systems, we make a first step in quantifying
the cumulative age distribution in globular cluster systems. Also here the
result for NGC 5846 leads us to the conclusion that its metal-rich globular
cluster population contains two globular cluster populations which differ in
age by several Gyr. The age structure for NGC 7192 shows instead strong
similarity with a single-age population.

Astrophysics