About 90% of XMM-Newton's observing time is made available via Announcements of Opportunity, which are open worldwide. In addition to this ``Open Time'', there is ``Calibration Time'', and Project Scientist's ``Discretionary Time''.
This Announcement solicits proposals to be carried out in the period defined in Section 1. About 80% of the available ``Open Time'' of this period is distributed via this call, which results in 12.0 Ms total observing time per year. The remaining 20% of the available ``Open Time'' will be distributed within the framework of joint programs, see Section 5.6.
``Open Time'' observations resulting from this Call for Proposals will be interleaved into the observing schedule, together with a few observations which failed or were not performed during the time period allocated to previous Announcements of Opportunity. A few observations approved in this call may be scheduled outside of the above period, depending on the visibility and science aimed.