Next: SAS processing Up: Maintenance procedures Previous: Maintenance procedures Contents . 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. ... Michael Smith 2011-09-20 ...