3.5 Joint HST-Chandra Observing Proposals

If your science project requires observations from both HST and the Chandra X-ray Observatory, then you can submit a single proposal to request time on both observatories to either the HST Cycle 16 or the Chandra Cycle 9 review. This avoids the "double jeopardy" of having to submit proposals to two separate reviews.

By agreement with the Chandra X-ray Center (CXC), STScI will be able to award up to 400 kiloseconds of Chandra observing time. Similarly the CXC will be able to award up to 100 orbits of HST time to highly rated proposals awarded Chandra time in its TAC process. 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. It is not essential that the project requires simultaneous Chandra and HST observations. Chandra time will only be awarded in conjunction with HST observations (and should not be proposed for in conjunction with an Archival Research or Theory Proposal).

Of the 400 kiloseconds of Chandra observing time that can be awarded in the HST review, only approximately 15% of the targets may be time-constrained. In addition, only one rapid TOO can be awarded (less than 20 days turn-around time). A Chandra TOO is defined as an interruption of a command load, which may include several predictable observations within that one-week load. HST Cycle 16 proposers should keep their Chandra requests within these limits.

Proposals for combined HST and Chandra observations should be submitted to the observatory that represents the prime science (not to both observatories). Similarly, proposals for observations with HST, Chandra and Spitzer ( Section 3.7) should only be submitted to the observatory that represents the prime science. The Chandra Cycle 9 deadline is 15 March 2007. While there is multi-wavelength expertise in the review panels for both observatories, typically the HST panels will be stronger in IR/optical/UV science and the Chandra panels in X-ray science.

Evaluation of the technical feasibility is the responsibility of the observer, who should review the Chandra documentation or consult with the CXC (see Section 9.4.1 for details). For proposals that are approved, the CXC will perform detailed feasibility checks in Chandra Cycle 9. The CXC reserves the right to reject any previously approved observation that proves infeasible, impossible to schedule, and/or dangerous to the Chandra instruments. Any Chandra observations that prove infeasible or impossible could jeopardize the overall science program and may cause revocation of the corresponding HST observations. Duplicate Chandra observations may also be rejected by the CXC.

Joint HST-Chandra Proposals must be identified in the 'Special Proposal Types' section of the proposal (see Section 8.10). Also, you must include technical information about the Chandra observations in the 'Coordinated Observations' section of the proposal (see Section 9.4.1).