How to Submit a Program Change Request (PCR)

Examples of minor and major program changes and directions for Program Change Requests (PCRs) for major requests to the Telescope Time Review Board (TTRB).

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Determine whether a modification is minor or major

Principal Investigators may make changes to their observing programs as outlined in the JWST Observing Program Modification Policy. Minor modifications can be made in consultation with the Program Coordinator and/or Instrument Scientist. Major modifications must be approved by the JWST Telescope Time Review Board (TTRB). Here are some examples of minor and major program changes:

Minor modifications 

  • Adjusting the celestial coordinates of a target by a few arcseconds;
  • Adding or changing filters or spectral elements;
  • Revising the distribution of science exposure times;
  • Changing the instrument parameters (e.g. sampling sequences).

Major modifications 

  • Adding or changing targets;
  • Adding or changing observing templates (e.g. from NIRCam Imaging to MIRI Imaging);
  • Requesting new use of a limited resource (e.g. Target of Opportunity);
  • Adding new constraints (e.g. orientation constraints) that significantly reduce the schedulability of an observation;
  • Requesting a time allocation increase.

Principal Investigators may contact their program coordinator or instrument scientist for help determining whether a program change is major or minor. STScI program coordinators and instrument scientists will check proposed changes for duplications with past and current cycle observations; any duplications must be approved by the TTRB.

Submit a program change request (PCR)

If a Program requires a major change, then the Principal Investigator may submit a Program Change Request (PCR) to the JWST Telescope Time Review Board (TTRB) and the JWST Science Policies Group (SPG).

Program Change Requests (PCRs) are submitted from a web browser navigated to the program's "Program Information" webpage that is located at the url

where the letters PID are replaced by the four-digit Program Identification number.

At the bottom of the Program Information page, under Requests, click "Request an Observing Change". To continue with submitting a major modification to the TTRB, click "Proceed with Major Change Request". Fill out

  • Your Name
  • Your Email
  • Select the Change Request Type (Target, Filter, Instrument, or Other)
  • Describe and Justify the Requested Changes

Submit your request.

Related links

JWST Observing Program Modification Policy

Policies for the Telescope Time Review Board

Notable updates
Originally published