XMM observes with all instruments simultaneously, brightness limits and other constraints permitting. All instruments can be operated independently (i.e., the exposure times of individual instruments are not coupled to each other) and observers will receive the science data of all science instruments operating during an observation.
When planning XMM observations several boundary conditions must be taken into account. The constraining parameters are listed in this section.
Note that part of the information provided in this chapter, in particular on target visibility during the mission, depends on the launch date.