IRAC and JHKs photometry of h and chi Persei

Within 25' of the cluster centers we detect ~11000 sources with J<=15.5, ~7000 sources with [4.5]<=15, and ~5000 sources with [8]<=14.5. In both clusters the surface density profiles derived from the 2MASS data decline with distance from the cluster centers as expected for a bound cluster.

Within 15' of the cluster centers, ~50% of the stars lie on a reddened ~13Myr isochrone; at 15'-25' from the cluster centers, ~40% lie on this isochrone. Thus, the optical/2MASS color-magnitude diagrams indicate that h and chi Per are accompanied by a halo population with roughly the same age and distance as the two dense clusters.