Star clusterings in the Carina complex:: UBVRI photometry of Bochum 9, 10 and 11

We report on the first UBVRI CCD photometry of three poorly known star clusterings in the region of eta Carinae: Bochum 9, 10 and 11. We find that they are young, rather poor, loose open clusters. We argue that Bochum 9 is probably a small and loose open cluster with about 30 probable members having E(B - V) = 0.63 +/- 0.08, located 4.6 kpc far from the Sun, beyond the Carina spiral arm. Similarly, Bochum 10 is a sparse aggregate with 14 probable members having E(B - V) 0.47 +/- 0.05 and at a distance of 2.7 kpc from the Sun. Finally, Bochum 11 is a less than 4 X 10(6) yr old cluster for which we identify 24 members. It has a reddening E(B - V) = 0.58 +/- 0.05, and lies between Bochum 10 and 9, at 3.5 kpc from the Sun. We propose that in the field of the cluster some stars might be pre-mainsequence candidates.