Absorption of the X ray background by the large magellanic cloud

Soft x ray flux of extragalactic origin should be partially absorbed during passage through the Large Magellanic Cloud. Past attempts to measure this absorption have been frustrated by the LMC's intrinsic x ray emission. New calibration techniques were developed to enable precise (within 5 pct.) measurement of the flux and spectrum of diffuse x rays detected by the Einstein Observatory IPC. These techniques were used to measure the absorption of extragalactic flux by neutral gas in the LMC, and to determine that at least 50 pct. of the observed flux in the 0.16 to 2 keV band is of extragalactic origin.