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Last Updated  May 23, 2017

James Webb Space Telescope (JWST) Guaranteed Time Observations (GTO) are awarded to scientists who deliver key JWST components.  Initial JWST Cycle 1 GTO proposals and descriptions of observations are due on April 1, 2017. Finalized JWST Cycle 1 GTO observation descriptions and targets will be publicly released by June 15, 2017


GTO Program PIs should submit their Science Descriptions and Observation Specifications by e-mail to jwstreview@stsci.eduThe formal deadline is 8 pm Eastern Daylight Time on April 1.

Important Dates

Stage 1

Release of the Cycle 1 call for GTO proposals

January 6, 2017

Cycle 1 GTO Science Descriptions and Observation Specifications due

April 1, 2017


APT version 25.2 Released (with final Cycle 1 overhead calculations)

June 1, 2017

Stage 2

GTO Observation Specifications Published (public)

June 15, 2017

Stage 3

GTO APT Technical Reviews and Revisions

July 28–September 15, 2017

Public release of GTO APT files

December 15, 2017


About This Document

Guaranteed Time Observations (GTO) reward both individuals and teams of scientists who were selected to deliver of key hardware and software components, or technical and inter-disciplinary knowledge for JWST. The program provides a total of about 16% use of the observatory over the first 3 cycles of operation. See the section JWST Cycle 1 GTO Proposal Submission Policies for information on who is eligible to submit, observing time requirements (including overheads), data rights, restrictions on types of observations, and other policy information.

Each JWST GTO is required to submit a description of the proposed Cycle 1 science program, including specific targets and specific observations using the templates provided. Those observations specifications will be reviewed and revised, and are required to be finalized at a date at least two months before the Cycle 1 GO Call is released, at which time the specifications will be made public. At the same time, GTOs must develop detailed observing proposals, which are required to be submitted using the Astronomer’s Proposal Tool.  The Cycle 1 GTO proposal submission process, therefore, has three stages: (1) preparation of the Science Descriptions and Observation Specifications templates(2) finalizing reservations for publishing observing specifications, and finally (3) Astronomer's Proposal Tool (APT) submissions for technical review and revisions. The section JWST Cycle 1 GTO Proposal Submission Process describes this process in full.


GTO Stage 1 Proposal and Observation Description Templates

Teams should complete the GTO Observation Specification Workbook [.xlsx] to provide descriptions of their observations for Cycle 1. The Guide to the Observation Specification Worksheet [.docx] gives brief details on the fields in each worksheet of the workbook. A GTO Proposal [.docx] should accompany the workbook, to provide general science summaries, coordinated parallel justifications (if applicable), and the breakdown of total hours to charge which programs. If you prefer, you may use this alternative total time charge table [.xlsx], provided by Pierre Ferruit.

 The proposal abstracts will be made public in the stage 2 release of the observation specifications.