This tool modifies the instrumental response to take into account the spatial degradation of the resolution when analyzing a moderately-extended (~1 arcmin) source. This uses the code developed by Andy Rasmussen of the Columbia University XMM-Newton RGS instrument team originally for the rgsxsrc convolution model available in xspec v11. The angular structure function is taken directly from an image (e.g., XMM-Newton EPIC, Chandra ACIS etc) where the user provides RA and Dec (2000) coordinates for the source, position angle of the spacecraft, and an aperture size suitable for the source.
The file input as the imgfil parameter is a text file giving the image filename, boresight, and source size in the following format :
RGS_XSOURCE_IMAGEFor example :
RGS_XSOURCE_BORESIGHT <05:25:02.9 -69:38:30 339.760974> RGS_XSOURCE_EXTRACTION <1.8>