Extremely red objects from the Hubble Space Telescope NICMOS parallel imaging survey

We present a catalog of extremely red objects (EROs) discovered using the H ubble Space Telescope Near Infrared Camera and Multi-Object Spectrometer (N ICMOS) parallel imaging database and ground-based optical follow-up observa tions. Within an area of 16 arcmin(2), we detect 15 objects with R-F160W > 5 and F160W < 21.5. We have also obtained K-band photometry for a subset of the 15 EROs. All of the R-F160W selected EROs imaged at K-band have R-K > 6. Our objects have F110W-F160W colors in the range 1.3-2.1, redder than th e cluster elliptical galaxies at z similar to 0.8 and nearly 1 mag redder t han the average population selected from the F160W images at the same depth . In addition, among only 22 NICMOS pointings, we detected two groups or cl usters in two fields; each contains three or more EROs, suggesting that ext remely red galaxies may be strongly clustered. At bright magnitudes with F1 60W < 19.5, the ERO surface density is similar to what has been measured by other surveys. At the limit of our sample, F160W = 21.5, our measured surf ace density is 0.94 +/- 0.24 arcmin(-2). Excluding the two possible groups or clusters and the one apparently stellar object reduces the surface densi ty to 0.38 +/- 0.15 arcmin(-2).