Evidence against a redshift z > 6 for the galaxy STIS123627+621755

The identification of galaxies at extreme distances provides the most direc t information about the earliest phases of galaxy formation. But at redshif ts z>5 even the most luminous galaxies appear faint; the interpretation of low signal-to-noise ratio data is difficult and misidentifications do occur . Here we report optical and near-infrared observations of the source STIS1 23627+621755, which was previously suggested to be at a redshift of 6.68 (r ef. 1). At that redshift, and with the reported 1 spectral energy distribut ion, the galaxy should be essentially invisible at wavelengths less than 9, 300 Angstrom, because the intervening intergalactic medium absorbs almost a ll light energetic enough to ionize neutral hydrogen-that is, with waveleng ths less than the redshifted Lyman limit of lambda = (1 + z) x 912 Angstrom . At near-infrared wavelengths, however, the galaxy should be relatively br ight. Here we report a detection of the galaxy at 6,700 Angstrom and a non- detection at a wavelength of 1.2 mum, contrary to expectations for z approx imate to 6.68. The data conservatively require that STIS123627+621755 has a redshift z< 6.