Diffuse high-energy flux drops during Earth transition

This simulation shows the passage of Earth through the field of view of Integral's IBIS/ISGRI gamma-ray imager, during the observations performed on 24 and 25 January 2006. The North Pole is indicated by a cross on Earth's disc, and the time on the top right corner is given in hours and minutes UTC. Earth is occulting the diffuse cosmic X-ray background (CXB), but its atmosphere is also emitting X-rays both through reflection of the CXB and through interaction with cosmic rays.

The occultation of the CXB resulted in one of the 'lightcurves' recorded by IBIS/ ISGRI (around 30-40 keV energy range), and here indicated by the dotted line. The asymmetry of the curve is due to the decreasing size of Earth as seen by Integral moving away from the planet on its orbit, and to enhanced cosmic-ray induced emission closer to the North Pole.