The extragalactic X‐ray background at 0.25 keV

We review recent results from shadowing experiments relating to the intensity of the extragalactic X‐ray background at 0.25 keV. The measurements appear to be converging on a value in the range 20 → 35 keV cm−2 s−1 keV−1. The implication is that over 80% of the background signal at 0.25 keV may have been resolved into discrete sources in the deepest pointed observations carried out by ROSAT.