The Two Micron All Sky Survey

Abstract

The Two Micron All Sky Survey (2MASS) will provide a uniform survey of the entire sky at three near-infrared wavebands: J (λ _{ef f} = 1.25μm), H (λ _{ef f} = 1.65μm), and K _s (λ _{ef f} = 2.16μm). A major goal of the survey is to probe large scale structures in the Milky Way and in the Local Universe, exploiting the relatively high transparency of the interstellar medium in the near-infrared, and the high near-infrared luminosities of evolved low-and intermediate-mass stars. A sensitive overview of the near-infrared sky is also an essential next step to maximize the gains achievable with infrared array technology. Our assessment of the astrophysical questions that might be addressed with these new arrays is currently limited by the very bright flux limit of the only preceding large scale near-infrared sky survey, the Two Micron Sky Survey carried out at Caltech in the late 1960’s (Neugebauer and Leighton 1969; hereafter, TMSS). Near-infrared instruments based on the new array technology have already obtained spectra of objects 1 million times fainter than the limit of the TMSS!