Detection of the (currently) most distant galaxy by narrow-band imaging (Hu et al 2002)



Narrowband 9152/118 AA image (left panel) and R-band image (right panel) of the emission-line object HCM 6A, which is marked with the vertical and horizontal lines. An image in the narrowband filter with a normalized local continuum (Z\/ band) subtracted (inset in left panel) shows that the object, which appears as two fragments, is a strong emission-line object. (We have slightl oversubtracted the Z\/ band to completely remove the neighboring galaxy, whose core appears white.) The galaxy is not seen in the much deeper R-band image (>8 hours on the Keck 10 m Telescope) or in a 5600 s F675W image taken with the WFPC2 camera on HST, shown in the insert in the right hand panel. The neighboring bright galaxy to the SW is a cluster member with a redshift of 0.375, so that the emission is not associated with this object -- in particular H-alpha lies shortward of the filter bandpass. The bar in the upper left corner of the narrowband image shows a 5'' scale.