An extremely red r(1/4) galaxy in the test image of the Hubble Deep Field South

We report the serendipitous discovery of an extremely red object in the Hub ble Deep Field South (HDFS) Test NICMOS (Near Infrared Camera and Multi Obj ect Spectrograph) field of view. The object is resolved in the NICMOS image and has a light profile very well described by an r(1/4) law with effectiv e radius r(e) = 0." 20 +/- 0.05 and H-AB = 21.7 +/- 0.1 magnitudes. In cont rast, the galaxy is undetected in the R and I band ground based images take n at the CTIO 4 m Blanco Telescope, giving a lower limit to the color of(R- H)(AB) > 3.9 and (I-H)(AB) > 3-5 at the 95% confidence level. The colors of a range of synthetic galactic spectra are computed, showing that the objec t is likely to be an "old" elliptical galaxy at redshift z greater than or similar to 1.7. Alternatively the colors can be reproduced by an "old" elli ptical galaxy at somewhat lower redshift (greater than or similar to 1) wit h significant amount of dust, or by a younger galaxy at higher redshift. Th is object represents a very interesting target for future VLT observations.