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G. A. Wegner, M. G. Hammell (Dartmouth ), G. B. Dalton, L. Moustakas, E. J. Olding, P. Allen (Oxford)
The ODTS covers 30 square degees in three separate 10 square degree regions of the sky centered at:
00:18 24 +34:52, 09:09:45 +40:50, and 16:39:30 +45:24.
An additional 11h field is being added on the celestial equator. The MDM Observatory 1.3-m and 2.4-m telescopes are being used to obtain a 3 sigma limiting magnitude to an intermediate depth of K ~19 mag. in these fields. This is being combined with CCD images from the Wide Field Camera at the prime focus of the 2.5-m Isaac Newton Telescope which provides deep (B = 26, V = 26, R = 26, i' = 24.5, and Z = 23) photometry in the same fields. At the time of writing, at our limiting K magnitude, we have detected large numbers of extremely red galaxies, EROs, with (R-K) > 6 and an observed surface density of ~0.03 per square arcmin based on a sample of more than 600 EROs found in the sub-area of the survey analyzed to date. Limited spectroscopic followup indicates two distinct populations in the EROs: old F-type uniform stellar populations with high implied formation redshifts and extremely dusty starburst objects. A significant fraction of the EROs occur in groups and appear to be tracers of clusters at z = 1-2. We are obtaining deep imaging and spectroscopy of these cluster candidates and looking at t he clustering properties of the galaxies.