XMM-Newton Phase II RPS Users Manual

5.2.4.4 Filling in RGS exposure settings

Depending on the instrument mode in which observations are to be carried out, a few more options can be specified for RGS. These can be defined on a dedicated page which can be accessed by pressing the ”Edit Details” button at the bottom of the exposure page.

Figure 16: Screen shot of an RGS-1 setting form. Note that CCD 7 is not available.

In the ”RGS Settings” form sheet, the only user-selectable parameter is the RGS CCD readout sequence. For standard observations over the whole energy range this sequence should not be changed. Only if users want to perform spectroscopy over a part of the RGS bandpass or read out one or more chips faster than others, a different sequence should be chosen. Each RGS has 9 CCD chips, but is read out in a cycle with up to 12 readout slots. The energy ranges covered by the different RGS CCDs in different grating orders are described in the XMM-Newton Users Handbook section 3.4.2 RFC arrays . If a user is interested in a particularly strong and scientifically important line, falling for example in chip #3, and wants to read this chip more often than all others, a readout sequence of, e.g., [3 1 2 3 4 5 3 6 3 8 9] could be chosen. This readout sequence implies that chip #3 will be read out 4 times more often than the others. Note that for RGS-1 and RGS-2 CCD 7 and CCD 4 are not available respectively.