A two-micron Galactic survey

Abstract

The first results are presented here of the Two-Micron Galactic Survey (TMGS). The TMGS is the most sensitive near-infrared survey of the Galactic plane yet attempted on a large scale. The Galactic plane has been drift-scanned in several regions over the areas $$-5^\circ\lt l\lt 30^\circ,|\,b\,|\le\, 5^\circ \enspace \text {and} \enspace 30^\circ \lt 180^\circ,\, |\,b\,|\le 5^\circ$$. The discussion in this paper concentrates mainly on three mapped areas centred on $$\delta = {-1}^{\circ},{-23}^{\circ}\enspace \text {and}\enspace {-30}^{\circ}$$, covering a total of 138 deg² of sky. The survey is complete in the areas covered to magnitude $${m}_\text {k} {\backsimeq} +{9.8}$$ mag. So far, a total area of 255 deg² has been mapped and 470 000 objects have been detected, the majority of these in the Galactic plane and with no known visible counterparts. About 90 per cent of IRAS point sources in the regions covered have been cross-correlated with our survey. The TMGS is detecting stars deep inside the bulge and has found extensive regions of exceptionally high extinction in the plane.