Put in one example that makes some attempt to simulate background and explain why this is, in general, difficult to get right.
There are several background components:
astrophysical background (AGN, X-ray binaries). Depends on location on sky.
instrumental background (Hard to simulate, but maybe can put in proxy spectrum?)
Put in one example that makes some attempt to simulate background and explain why this is, in general, difficult to get right. There are several background components:
Often background is not an issue in Chandra.