The surface density of extremely red objects

We present initial results from a field survey for extremely red objects [E ROs, defined here as (R-K') greater than or equal to 6 mag] covering 154 ar cmin(2) of sky, from the first of seven deep, wide-field K' images obtained as part of the Calar Alto Deep Imaging Survey (CADIS). The 5 sigma point s ource detection limits are K' = 20.5 mag and R = 25.0 mag, while extended-s ource limits are up to 0.50-0.75 mag brighter. We identify a total of eight bright EROs with K' less than or equal to 19.0 mag. Six of these bright ER Os are resolved and are likely to be galaxies, while the remaining two are unresolved, with colors consistent with their being low-mass galactic stars . We derive a surface density for the six bright, extragalactic EROs of 0.0 39 +/-0.016 arcmin(-2), which is higher by a factor of 4 than previous valu es. We estimate that the volume density of bright EROs to be as high as tha t of nearby Seyfert galaxies.