SAS Watchout

Why has the flux I get from fitting XMM-Newton RGS spectra changed in SAS v22?

In SAS v22.0 the parameter defaults in rgsrmfgen have changed so that a rectification to the effective areas is turned on by default:

withrectification=yes

this increases flux returned by RGS spectral fitting by a quantity dependent on the wavelength and on the observation date. See CAL-SRN-401 for details.