Beginning in Cycle 5, NIRISS SOSS enabled four new "multistripe" subarrays that facilitate faster readouts of the standard SUBSTRIP256 subarray footprint. At their limit, these subarrays enable unsaturated observations of all currently known transiting exoplanet systems, accommodating targets as bright as J ~ 3.5 mag. 

Calibration efforts for the new subarrays are close to completion and the first time-series observation was successfully conducted on July 29, 2026, for the exoplanet WASP-18b (CAL-12564). Figure 1 shows preliminary reduced time-series light curves capturing the transit of WASP-18b for each individual stripe within the SUB680STRIPE_SOSS subarray. A more detailed evaluation of the performance of SOSS multistripe is ongoing and will be reported publicly through a collection of technical reports in the coming months. 

On August 20^th, JWebbinar 52 - Developments in Instrument Modes and Capabilities for JWST Cycle 6, will provide a detailed update on multistripe commissioning efforts. Observers are encouraged to attend the JWebbinar and contact the NIRISS team via the JWST Help Desk with any questions.