The JWST Exposure Time Calculator (ETC) allows you to define sources, place them in , and use the scenes in calculations. Sources may be used in multiple scenes, and scenes may be used by multiple calculations, which will be automatically recalculated to reflect any changes made. Reasonable default values are provided for all fields. Workbooks for users who are logged-in using MyST accounts are automatically saved and will be available in your workbook list upon return. Workbooks created as an anonymous user are not preserved and will not be available upon login the next time.
The recommended workflow is "copy and modify": create a default object (source, scene, or calculation), then modify it, then copy it and modify it further. Calculation results can be overplotted for easy comparison.
Get your own copy of the pre-populated Sample Workbooks to play with, or get started from a new workbook:
On the Scenes and Sources tab window:
- Create one or more sources. A default scene with one default source is already available when a new workbook is created. The default source is a point source with flat continuum spectrum. For each source, you may specify the Continuum, Renorm (normalization), Redshift, Extinction, emission Lines, and Shape. Be sure to click Save before moving to a different source.
- click on a row to select a source for editing
- check one or more Plot checkboxes to see the source spectra
- to upload your , select the Upload Spectra tab to upload one or more spectra. When you return to Scenes and Sources, your uploaded spectra will appear in a dropdown menu in the Continuum tab under the "Source Editor."
- . Add one or more sources to the scene: for each source, specify its offset from the center (and orientation, for extended sources). Be sure to click Save before moving to a different source.
- click on a row to select a scene for editing
- this will automatically update the "Scene Sketch" panel below it
On the Calculations tab window:
- Create a calculation by clicking one of the instrument buttons and selecting one of the modes. For each calculation, you may specify the Scene, backgrounds, the instrument configuration and exposure parameters, and the extraction strategy parameters.
Investigate the Edit menu for copy and delete options, and the Expand menu for systematic explorations of parameter space.