ESA has announced that INTEGRAL operations will be terminated at the end of 2024. As such the INTEGRAL - Fermi joint observation program covers only the first 4-months of Cycle-17 and terminates thereafter.
Observations in the low and medium energy gamma-ray range made with the INTErnational Gamma Ray Astrophysics Laboratory (INTEGRAL) can enhance the value of Fermi's scientific explorations and vice versa. This Fermi-INTEGRAL cooperative agreement, developed between NASA and ESA, has thus been established to commit observing time with INTEGRAL to be coordinated with specific Fermi scientific studies. These observations will be awarded on a competitive basis. The scientific programs supported within this arrangement will be those whose scientific value is most significantly enhanced by the combination of Fermi and INTEGRAL observations.
Specifically, investigators affiliated with and resident at US institutions proposing to the Fermi program are eligible to be awarded observing time on INTEGRAL. It is also required that the observations proposed do not conflict with an existing program or one concurrently proposed to ESA, that they can be accommodated into the INTEGRAL observation timeline, and that they are technically feasible. A total of 250 ks of INTEGRAL open program observation time has been made available for this joint program. Requests for time-constrained observations or target of opportunity (ToO) observations are permissible provided that they comply with the usual restrictions detailed in the INTEGRAL Announcement of Opportunity (AO) documentation.
Requests for non-standard observation strategies, i.e. employing dither patterns other than the standard 5oX5o Rectangular or Hex strategies, cannot be accommodated under this joint program. Such observation requests must instead be made directly to ESA through the usual INTEGRAL AO process. The INTEGRAL data obtained under this joint agreement will be archived as usual, and become publicly available without delay. The Fermi data, like all Fermi science data, will also be made public shortly after it is obtained.
Observations in compliance with these guidelines that are selected by the Fermi peer-review process will be designated as priority A in the ISOC scheduling and planning process.
Proposers intending to request joint INTEGRAL observations are strongly encouraged to first review the mission specific information available from the INTEGRAL Science Operations Centre (ISOC) web site. They will also be required to append a brief technical justification, comprising one-page or less of text, to their regular 4-page (or 6-page in the case of large projects) scientific justification text. This technical justification should include all pertinent details for the desired observation(s). Specifically, for each requested observation, the technical justification page should include all of the information that would normally be entered on the Observation Page of the ISOC's Proposal Generation Tool (PGT): the requested duration in kiloseconds, the source name, RA and Dec, expected flux on the user-specified energy range (within the overall IBIS and/or SPI bandpass), extended or point source (and the angular size in the case of the latter) and the desired dither pattern (either 5oX5o Rectangular or Hex). A justification for the requested amount of observation time should also be presented in this section. A technical evaluation of the proposed INTEGRAL observations will be made by the ISOC staff prior to the Fermi proposal review and that information will be made available to the Fermi peer review committees.
Apart from the above, both missions' general policies and procedures currently in force for the final selection of proposals, the allocation of observing time or grant support, and the execution of the observations remain unchanged.