COBE DIFFUSE INFRARED BACKGROUND EXPERIMENT OBSERVATIONS OF THE GALACTIC BULGE

Low angular resolution maps of the Galactic bulge at 1.25, 2.2, 3.5, a nd 4.9 mu m obtained by the Diffuse Infrared Background Experiment (DI RBE) onboard NASA's Cosmic Background Explorer (COBE) are presented. A fter correction for extinction and subtraction of an empirical model f or the Galactic disk, the surface brightness distribution of the bulge resembles a flattened ellipse with a minor-to-major axis ratio of app roximate to 0.6. The bulge minor axis scale height is found to be 2.de grees 1 +/- 0.degrees 2 for all four near-infrared wavelengths. Asymme tries in the longitudinal distribution of bulge brightness contours ar e qualitatively consistent with those expected for a triaxial bar with its near end in the first Galactic quadrant (0 degrees < l < 90 degre es). There is no evidence for an out-of-plane tilt of such a bar.