If your science project requires observations from both HST and the XMM-Newton Observatory, you can submit a single proposal to request time on both observatories to either the HST Cycle 20 or the XMM-Newton Cycle AO-11 review.
By agreement with the XMM-Newton Observatory, the HST TACs will be able to award up to 150 kiloseconds of XMM-Newton observing time. Similarly the XMM-Newton TACs will be able to award up to 30 orbits of HST time. The only criterion above and beyond the usual review criteria is that the project is fundamentally of a multi-wavelength nature, and that both sets of data are required to meet the science goals. XMM-Newton time will only be awarded in conjunction with new HST observations (and should not be proposed for in conjunction with an Archival Research or Theory Proposal). Proposers should take special care in justifying both the scientific and technical reasons for requesting time on both missions.
It is not essential that the project requires simultaneous XMM-Newton and HST observations. No observations with a reaction time of less than 5 working days from the trigger date will be considered. Target of Opportunity (ToO) proposals must state explicitly whether the HST observations require a disruptive ToO. No more than one disruptive ToO will be allocated per proposal. It is the responsibility of the PI to inform both observatories immediately if the trigger criterion is fulfilled.
Joint HST/XMM-Newton Proposals should be submitted to the observatory that represents the prime science facility (not to both observatories). Since the XMM-Newton AO-11 submission deadline has passed (7 October 2011), only joint proposals where HST is the prime science facility should be submitted in response to this call.
Establishing technical feasibility is the responsibility of the PI, who should review the XMM-Newton and HST Calls for Proposals and Instrument Handbooks. All standard observing restrictions for both observatories apply to joint proposals. For proposals that are approved, both projects will perform detailed feasibility checks. Both projects reserve the right to reject any approved observation that is in conflict with safety or schedule constraints, or is otherwise deemed to be non-feasible.
