Science data obtained from JWST is governed by a mission policy similar to that adopted for HST and will be released to the astronomical community following an exclusive access period (EAP). During this period access to archived data is limited to authenticated and authorized persons, which generally consists of the principal investigator team. However, all MAST users can search for science observations and view metadata related to planned and executed observations at any time, even during the EAP. Pre-images, such as those used to support NIRSpec target acquisition, as well as guide star data obtained during an observation, also have EAP protection.

The exclusive access period allows investigators who proposed observations the time to formulate and publish scientific results of their program. This period applies at the data product level (rather than to a completed observing program), and begins the moment that individual exposures obtained from the spacecraft have been calibrated and made available in MAST. The duration of the exclusive access period depends in part upon the type of observing program used to obtain the data, as summarized in the Data Rights and Duplications section of the Call for Proposals for the current cycle (see, for example., the relevant page for Cycle 3). Some programs, whether by policy or choice, have a zero-length EAP.

Principal investigators (PIs) have the option of waiving all or part of their exclusive access period; in certain limited cases the STScI director may grant a request for an extension. Note that all data, whether or not access is restricted within MAST, may be used by authorized JWST project staff for monitoring and diagnostic purposes. See the policy explained in the Data Rights and Data Dissemination article for details. Access to EAP data in MAST requires users to establish electronic credentials with STScI; browsing and retrieval of such data requires both authentication of the user credentials and authorization to access data from particular programs.

Granting access to EAP data

PIs of programs may authorize access to specific users for their data during the EAP period by navigating to the MyST screen (Figure 1) and clicking on Launch under "Registered User." Figure 2 shows the subsequent MyST Home screen for registered users; click the Launch button under "Update," then scroll to the Manage Access to Exclusive Access Data pull-down menu. From there select your program and enter the MyST email address of record for your colleague.