IzJHKs photometry of Collinder 359

This study is part of a large programme aimed at examining the dependence of the mass function on environment and time. We have surveyed 1.6 square degrees in the cluster, in the I and z filters, with the CFH12K camera on the Canada-France-Hawaii 3.6-m telescope down to completeness and detection limits in both filters of 22.0 and 24.0mag, respectively.

Based on their location in the optical (I-z,I) colour-magnitude diagram, we have extracted new cluster member candidates in Collinder 359 spanning 1.3-0.03M_{sun}_, assuming an age of 60Myr and a distance of 450pc for the cluster. We have used the 2MASS database as well as our own near-infrared photometry to examine the membership status of the optically-selected cluster candidates. Comparison of the location of the most massive members in Collinder 359 in a (B-V,V) diagram with theoretical isochrones suggests that Collinder 359 is older than Alpha Per but younger than the Pleiades.