Science Use Cases walk users through all elements of a JWST observing program, from posing a question, to identifying an instrument-specific mode optimized to answer this question posed. These examples use Exposure Time Calculator simulations to estimate reasonable exposure times, and illustrate how to specify the observations in the Astronomers Proposal Tool (APT).
As part of the single stream process, JWST proposals will require a detailed technical justification and Astronomers Proposal Tool (APT) executable. Proposals may require significantly more preparation compared to HST. While APT provides some templates for some of the most common observing modes (see Figure 1), some observing scenarios are more complicated. The science use cases listed below provide a guide for crafting the technical aspects to your proposal, including how to use the Exposure Time Calculator (ETC) and APT.