The UKST Flair-Denis Survey

Abstract

DENIS is a major survey to map the southern hemisphere in the I (0.8µm), J (1.25µm) and K s (2.15µm) bands using the dedicated ESO 1.0m telescope and is the European equivalent of the 2MASS survey. The survey should be complete by 1999. Although primarily intended for stellar science through the detection of point sources with fluxes ≤1 mJy (e.g. detection of brown dwarf candidates and obscured regions of star formation) an important extra application is the capability to obtain a complete view of the local Universe out to z ∼ 0.07 by virtue of a ‘clean’ near-IR selected bandpass. Here selected galaxies are less susceptible to extinction in our own Galaxy (e.g. Reike et al 1993, ApJ,336,752) and by internal absorption of the host galaxy (e.g. Rix 1993, PASP,105,999). Samples can be obtained through the ZOA whilst stellar populations of even highly dusty galaxies can be discerned. Total galaxy luminosity at 1–2 µm is thought to trace the stellar mass in a galaxy, as it sees to the galaxies ‘backbone’ unlike the B band which is biased by effects of recent star formation. Hence a sample less biased by star-formation and internal or galactic extinction, should be produced. Assuming that stellar mass follows total galaxy mass (including dark matter) then a NIR survey should be a good way of measuring the local matter distribution. Hence a J/K s selected sample is an obvious choice for a southern sky redshift survey, being less susceptible to problems biasing optical or IRAS samples ...