THE SOUTH-POLE NEAR-INFRARED SKY BRIGHTNESS

We report our finding that the South Pole is the darkest known Earth-b ased site for near-infrared astronomical observations. For this reason it has great potential for the most sensitive surveys of distant or f aint objects, The find that the south polar sky background is substant ially 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 ac companying paper by Ashley kt al, (1996, PASP, 108, 721) and is compar able to the sky brightness measured by high-altitude balloon at 2.4 mu m (Matsumato et al, 1994, PASP, 106, 1217).