2000AJ....119.1519H

Images of the Hubble Deep Field (HDF) at 3.2 µm, taken with the 10 m Keck Telescope, are presented. The images cover a total area of ∼2.5 arcmin². To a 5 σ limit of [3.2]_tot~17.5 mag (Vega relative), 11 sources are detected, nine of which are extragalactic. The integrated galaxy number counts are therefore ∼1.3x10⁴ deg^–2 to this depth. The galaxies detected at 3.2 µm have a median redshift of z=0.56. All 3.2 µm sources have 1.6 µm, 1.1 µm, and visual counterparts, all of fairly regular morphology; several also have 6.7 µm, 15 µm, 850 µm, 8.5 GHz, or 1.4 GHz counterparts. No sources are found that are either anomalously red or anomalously blue in their H-[3.2] color, and there are significant detections of most of the known near-infrared HDF sources for which detection in these 3.2 µm data seemed likely.