This page provides the sky background expected at the TAO site. The sky background consists of near-infrared (NIR) continuous emission (only for NIR data), airglow (only for NIR data), and atmospheric thermal emission. The near-infrared continuous emission and the airglow emission are calculated based on the Gemini Observatory's model. The atmospheric emission is calculated based on the atmospheric transmittance given on the another page predicted by the ATRAN model (Lord, S. D., 1992, NASA Technical Memorandum 103957). The emissivity and temperature of the atmosphere are assumed to be 1 - transmittance and 240 K, respectively. The precipitable water vapor (PWV) toward the zenith is set to 0.3, 0.5, 0.7, 0.9, 1.2, and 1.5 mm.