A study of extremely red objects

We present preliminary results from a near-infrared photometric study of a sample of EROs from the Calar Alto Deep Imaging Survey. More than half of the sample has been imaged to date. The majority of the EROs have near-infrared colors consistent with their being elliptical galaxies at z similar to 1. However, a more detailed look at one of the EROs shows some ambiguity in this interpretation. We obtain equally good fits to g-filter photometry with single stellar population assuming either a dust-free old model or a young dusty model. While photometric redshifts work well for the majority of objects in a multicolor sample, EROs are not yet understood well enough that photometric redshifts can be used as a reliable tool.