We report the serendipitous discovery of an extremely red object in the Hubble Deep Field South (HDFS) Test NICMOS (Near Infrared Camera and Multi Object 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 effective radius re=0.′′20±0.05 and Hab=21.7±0.1 magnitudes. In contrast, the galaxy is undetected in the R and I band ground based images taken 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 object is likely to be an “old” elliptical galaxy at redshift z>∼1.7. Alternatively the colors can be reproduced by an “old” elliptical galaxy at somewhat lower redshift (>∼1) with significant amount of dust, or by a younger galaxy at higher redshift. This object represents a very interesting target for future VLT observations (Refer to PDF file for exact formulas).

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Also archived in: arXiv: astro-ph/9808282 v1 25 Aug 1998 The authors would like to thank R. P. van der Marel, who developed the Pedestal Estimation Software used for the pedestal subtraction. TT would like to thank Prof. G. Bertin for carefully reading the manuscript.ISSN:1432-0746 Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type


Department, Program, or Center

School of Physics and Astronomy (COS)


RIT – Main Campus