Calibration Access and Data Handbook

Selection of observations of empty RGS files

Suitable observations should be longer than about 20 ksec, cover all the considered time period, and have different background levels, in particular the highest ones, so the sample should include observations taken at the beginning and end of the science window. It is helpful to consider objects for which no RGS spectrum is expected or to look at the RGS monitor pages.

Each observation must be examined to check that there is no significant RGS signal. This can be done by inspection of

• image and banana images in the PPS
• cross-dispersion distribution of RGS events with SAS or IDL