2005A&A...443..831H

We present the results of a wide-field survey for extremely red objects (EROs), based on J and R band imaging. The survey covers 2.89 deg², consisting of 50 single fields, each approximately 210-arcmin² in size. This survey provides a sample of 60 extended objects with a colour of R-J≥5 and J band magnitudes more than 10σ above background (18mag≤J≤20mag). Thirty five of these objects have been detected in both J and R-band. We derive a surface density for such EROs of 5.7±0.1x10^–3arcmin^–2, which is about seven times lower than for galaxies with R-K≥6. Stellar population models suggest that these EROs are massive galaxies with an old stellar population in a redshift range of 1.4≤z ≤3.0. For this scenario, we estimate the co-moving volume density to be (9.57±1.24)x10^–6Mpc^–3.