COSMIC X-RAY BACKGROUND AND EARTH ALBEDO SPECTRA WITH SWIFT BAT

We use Swift BAT Earth occultation data at different geomagnetic latitudes to derive a sensitive measurement of the cosmic X-ray background (CXB) and of the Earth albedo emission in the 15-200 keV band. We compare our CXB spectrum with recent (INTEGRAL, BeppoSAX) and past results (HEAO-1) and find good agreement. Using an independent measurement of the CXB spectrum we are able to confirm our results. This study shows that the BAT CXB spectrum has a normalization similar to 8% +/- 3% larger than the HEAO-1 measurement. The BAT accurate Earth albedo spectrum can be used to predict the level of photon background for satellites in low Earth and mid inclination orbits.