Scientific goals of the UKIRT Infrared Deep Sky Survey

UKIDSS is the next generation near-infrared sky survey. The survey will commence in early 2004, and over 7 years will collect 100 times as many photons as 2MASS. UKIDSS will use the UKIRT Wide Field Camera to survey 7500 square degrees of the northern sky, extending over both high and low Galactic latitudes, in JHK to K=18.5 (over three magnitudes deeper than 2MASS). UKIDSS will be the true near-infrared counterpart to the Sloan survey, and will produce as well a panoramic clear atlas of the Galactic plane. In fact UKIDSS is made up of five surveys and includes two deep extra-Galactic elements, one covering 35 square degrees to K=21, and the other reaching K=23 over 0.77 square degrees. This paper provides the details of the five UKIDSS surveys and describes the main science goals.