|HST Call for Proposals for Cycle 25|
2.3 Scientists of any nationality or affiliation may submit an HST proposal. Endorsement signatures are not required for Phase I observing proposals (unless required by the regulations of the proposing institution).Each proposal must have a Principal Investigator (PI), who is responsible for the scientific conduct of the project. A Co-PI option is also available, allowing two or more proposers to share the scientific responsibility of the project. Any other individuals who are actively involved in the proposal should be listed as Co-Investigators (Co-Is). The proposal itself may be submitted through APT by either the PI or a Co-I.Proposals by non-U.S. PIs that have one or more U.S. Co-Is must designate one of the U.S. Co-Is as the Administrative PI (Admin PI; see Section 8.13). This person will have overall oversight and responsibility for the budget submissions of the U.S. Co-Is in Phase II (see Chapter 11 for funding eligibility requirements). All proposals have the option of designating a Contact Co-I, who will serve as the contact person for that proposal. The PI remains responsible for oversight of the proposal.All proposals are reviewed without regard to the nationalities or affiliations of the investigators.2.3.2 ESA ScientistsAn agreement between NASA and ESA states that a minimum of 15% of HST observing time (on average over the lifetime of the HST project) will be allocated to scientists from ESA member states. It is anticipated that this requirement will continue to be satisfied via the normal selection process, as it has been in previous cycles. ESA scientists will be identified automatically by APT based on the institution selected; the ESA flag will only be visible in the PDF output.2.3.3 Student PIsObserving proposals from student PIs will be considered. These proposals should be accompanied by a letter from the student's faculty advisor certifying that:This letter from the advisor should be e-mailed before the proposal deadline to firstname.lastname@example.org.