XMM-Newton Science Analysis System


bkgfit (ebkgmap-2.10.2) [xmmsas_20230412_1735-21.0.0]

Input Files

There are three types of FITS image input, listed below. All input images must share the same dimensions.

1. A Poissonian image $I$, that is, an image for which the values are random, non-negative integers which obey a Poisson probability distribution about a conjectural image of expectation values $<I>$. This image may have any numeric data type, but it is converted within the task to 16-bit integer.

2. A list of $N$ model component images $\mathbf{b}$. The task bkgfit calculates amplitudes $\mathbf{a}$ such that $\sum_{i}^{N} a_i b_i$ approximates $<I>$, the expectation value of $I$. The component images may have any numeric datatype but are converted within the task to 32-bit reals. Negative values are not permitted in any component, no component image may be all zero, and components which are too similar should be avoided.

3. (Optional) a mask image. This may have any numeric data type but is converted within the task to 1-bit logical. The conversion rule is that values $>0$ give TRUE, all others FALSE. Only those pixels for which the mask is TRUE are fitted.