JWST Observation Duplication Checking
Users are responsible for checking their proposed observations for potential duplications against accepted or previously executed observations, and either removing the duplication or explaining any such potential duplications in their science proposals. Please visit the MAST page on Duplication Checking for Proposals for the most up-to-date information and recommendations.
On this page
See also: JWST Duplication policy
Relevant Links outside of JDox: Guidelines for duplication checking can be found on the MAST Duplication Checking for Proposals page. MAST JWST Duplicate Observations Portal, MAST Data Discovery Portal and JWST Program ID Look-up GUI
As part of maximizing the science return of JWST, unnecessary duplication of observations needs to be avoided. Proposed observations that duplicate or potentially duplicate existing or planned observations must be scientifically justified by the proposer. The JWST Duplication Policy defines what constitutes a duplication.
Duplication checking prior to submission is the proposer's responsibility. Any duplications or potential duplications (for programs where the details are not known up front) must be discussed and/or justified in the text of the proposal. Failure to do so may result in the rejection of the proposed observation even after proposal acceptance. For accepted proposals, STScI will perform a detailed duplication check to catch and remove any duplications within the current pool of accepted proposals.
Pre-submission checking
See also: JWST Duplication Policy
Relevant Links outside of JDox: Guidelines for duplication checking can be found on the MAST Duplication Checking for Proposals page. Summary listings of accepted GTO Program Information and ERS Program Information including links to the public APT files.
To avoid unintentional duplications, proposers will be required to check their proposed observations against those already approved (both in the queue and previously observed). As JWST observations are obtained and archived, all observations are placed into the Mikulski Archive for Space Telescopes (MAST), forming the basis for duplication checking.
Note: You may want to perform this duplication checking step prior to going through the effort of entering and validating your own APT proposal, to avoid the potential of finding out after the fact that your observations had already been proposed. If there is a scientific justification for a duplication, such as a time-variable source or need for higher signal to noise than in the previously approved JWST observations, you can still request it but you should provide a justification for it in your science proposal text.
The MAST Duplication Checking for Proposals page describes tools and strategies for identifying and understanding potential duplications. It is the proposer's responsibility to determine if matching observations are genuine duplicates according to the policy.
Post-acceptance checking
Once a proposal is accepted, one of the first steps in proposal processing is a duplication check performed by STScI staff. Their software not only checks for duplications against previous and planned observations, but also checks the pool of accepted programs in a given cycle to catch any new or unintended potential duplications. STScI will contact affected PIs to resolve any such duplications if they occur.