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Guaranteed Time Observation Programs

The JWST Guaranteed Time Observations (GTO) program is designed to reward scientists who helped develop the key hardware and software components or technical and inter-disciplinary knowledge for the observatory. The program provides a total of about 16% use of the observatory over the first 3 cycles of operation.

  • Archival Research

    Programs with this icon have components that have no exclusive access period, and can be used as a basis for GO Archival  Research (AR) Proposals.

GTO Programs by Cycle


BOTS = Bright Object Time-series

FS = Fixed Slit

GTS = Grism Time Series

IFU = Integral Field Unit

LRS = Low Resolution Spectroscopy

MOS = Multi-object Spectroscopy

MRS = Medium Resolution Spectroscopy

SOSS = Single-object Slitless Spectroscopy

TSO = Time Series Observation

WFSS = Wide Field Slitless Spectroscopy


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For technical assistance, please contact the JWST Help Desk.


The NASA James Webb Space Telescope, developed in partnership with ESA and CSA, is operated by AURA’s Space Telescope Science Institute.