L Dwarfs Found in Sloan Digital Sky Survey Commissioning Imaging Data

This paper describes the discovery of seven dwarf objects of spectral type `L' (objects cooler than the latest M dwarfs) in commissioning imaging data taken by the Sloan Digital Sky Survey (SDSS). Low-resolution spectroscopy shows that these objects have spectral types from L0 to L8. Comparison of the SDSS and 2MASS photometry for several of these objects indicates the presence of significant opacity at optical wavelengths, perhaps due to atmospheric dust. This comparison also demonstrates the high astrometric accuracy (better than 1'' for these faint sources) of both surveys. The L dwarfs are shown to occupy a distinctive region of color-color space as measured in the SDSS filters, which should enable their identification in a straightforward way. This should lead eventually to a complete sample of many hundreds of these low mass objects, or about one per 15 square degrees to i'~20, in the complete SDSS data set.