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Guest Investigator Program

The Swift Guest Investigator Program is an annual announcement of opportunity soliciting proposals from the community for research relevant to the Swift mission. The GI programs begin at the start of each April and last for approximately 12 months (Cycle 20 runs from 1st April 2024 until 31st March 2025). Observing time is available for scientists at both US and non-US institutions, although only those Principal Investigators at US institutions will be eligible for funding from NASA. No funding is provided for the fill-in category.

GI Cycle 20: Deadline Passed

Swift provides an opportunity for simultaneous optical to hard X-ray observations of targets, allowing broad-band analysis. The X-ray Telescope is specifically designed to choose the best operating mode for the X-ray flux of the object in question.

As initiated several years ago, there will be dual anonymous peer review for Cycle 19. See for more details.

There is again a Key Projects category. Such projects are intended to provide significant advances in Swift science, and require a very strong justification. In these cases, 6 pages are allowed for the scientific justification (4 pages only are allowed for all other proposals).

Cycle 20 again includes the option to submit a single proposal for combined observing programs between Swift and XMM-Newton, Chandra, INTEGRAL, NRAO (VLA, GBT and VLBA), NuSTAR and NICER. More details are available on the main GI page. Coordinated observations with IXPE and LCO are encouraged, though these will require separate proposals to both facilities; that is, neither IXPE nor LCO time can be awarded directly though the Swift GI program.

In this cycle, there will be up to 2 Ms available for non-ToO targets, 1 Ms for ToOs, 1 Ms for large programs and 1 Ms for fill-in targets. ToOs for GRBs detected with instruments other than Swift (e.g., MAXI, Fermi, IPN) are included in this time.

Requests for fill-in observations cannot be time-constrained (e.g. coordinated with ground- or space-based facilities), although both ToOs and non-ToOs may be, provided the window for the observation exceeds 3 hours. There is no restriction on the maximum number of time-constrained observations permitted, and no funding is provided for these proposals.

The duration of an observation (ie a single visit to a target) is limited to between 1 and 40 ks, although several observations may be requested. No single pointing of longer than 1.8 ks will be performed, however.

Proposals must be submitted through the Astrophysics Research Knowledgebase/Remote Proposal System (ARK/RPS) ( for which you need an account. The page for submission is (once you are logged in). There are instructions regarding the steps required.

See the NASA page for more details (FAQs), or contact the Leicester Swift help-desk.

List of Cycle 19 (2023-2024) accepted targets

List of Cycle 20 (2024-2025) accepted targets

Previous Cycles

Cycle 19 (2023-2024)
Cycle 18 (2022-2023)
Cycle 17 (2021-2022)
Cycle 16 (2020-2021)
Cycle 15 (2019-2020)
Cycle 14 (2018-2019)
Cycle 13 (2017-2018)
Cycle 12 (2016-2017)
Cycle 11 (2015-2016)
Cycle 10 (2014-2015)
Cycle 9 (2013-2014)
Cycle 8 (2012-2013)