The south pole near-infrared sky brightness

We report our finding that the South Pole is the darkest known Earth-based site for near-infrared astronomical observations. For this reason it has great potential for the most sensitive surveys of distant or faint objects, The find that the south polar sky background is substantially darker in the standard near-infrared J, H, and K Alters, and in an optimized K-DARK filter centered at 2.36 mu m. In particular, the K-DARK background at the South Pole is only 162 +/- 67 mu Jy arcsec(-2) at the zenith. This is consistent with the results described in an accompanying paper by Ashley kt al, (1996, PASP, 108, 721) and is comparable to the sky brightness measured by high-altitude balloon at 2.4 mu m (Matsumato et al, 1994, PASP, 106, 1217).