A Rocket-Borne Observation of the Near-Infrared Sky Brightness

In a search for extragalactic background radiation, we measured the absolute sky brightness at high galactic latitude at near-infrared wavelengths (1.4-4 microns) using a liquid-helium-cooled spectrometer flown onboard the Japanese rocket S-520-15. For the purpose of estimating statistical and systematic uncertainties for future experiments, the instrumentation, the calibration and the performance are described in detail. The observations clearly show time-dependent components of terrestrial and environmental origin. The observed residual brightness was slightly brighter than that of previous rocket-borne experiments and the recent result of COBE/DIRBE. We set upper limits on the extragalactic continuum intensity of lambda*I_labmda<2.0 x 10^-11 Wcm^-2sr^-1 at 2.5 microns and <2.5X10^-11 Wcm^-2sr^-1 at 4.0 microns and on the extragalactic line intensity of I<5>10^-13 Wcm^-2sr^-1 at 1.7-2.5 microns. (SECTION: Cosmology)