XMM-Newton Science Analysis System


evigweight (evigweight-1.8) [xmmsas_20230412_1735-21.0.0]

Spatial analysis

In the same way, constructing an image $D'(\alpha,\delta)$ of the source within the energy band $E_1,E_2$ may be done by calling evselect (with withzcolumn=Y withzerrorcolumn=N) :

	$$D'(\alpha,\delta)$$	$=$	$$\sum_{E_1 < E_j < E_2} w_j \: / \: T_{exp}$$	(9)
	$$\sigma(D'(\alpha,\delta))$$	$=$	$$\sqrt{\sum_j w_j^2} \: / \: T_{exp}$$	(10)

This is directly proportional to the source brightness (no need to divide by the exposure map), except for bad pixels and CCD gaps (see Sect.3.9).