JWST ETC Using the Sample Workbooks

Sample workbooks are designed with illustrative calculations to help users get started using the JWST Exposure Time Calculator (ETC)

On this page

        Video Tutorial:  ETC Workbooks

Words in bold are GUI menus/
panels or data software packages; 
bold italics are buttons in GUI
tools or package parameters.

The Available Workbooks pane can be populated by retrieving a set of sample workbooks for all 4 JWST science instruments which include imaging, slitted, slitless, and IFU spectroscopy, and coronagraphic imaging calculations. These workbooks are organized in alphabetical order in the drop-down menu. Workbooks include pre-defined sources and scenes for calculations. The sample workbooks can assist users in scenes, sources, and calculations from basic to more complex calculations.

Available workbooks

Figure 1. Layout of the Available Workbooks page

Click on the figure for a larger view.

Workbooks available to users are listed in the Available Workbooks pane. This list can be populated by shared workbooks from other users, adding workbooks from the sample workbooks list, or by creating a new workbook by clicking the CREATE NEW WORKBOOK button. Please visit the sharing workbooks page to learn more about sharing workbooks. 

A description of each column name is below:

#: Workbooks can be referenced by an ID number.

Name: The name of the available workbook.

Ver: Populated when a workbook was created in a previous version of the ETC. This column is blank for workbooks created in the current version of the ETC. 

Load: Load and access sample workbook.

Description: Brief description of the calculations contained in the workbook. 

Options: Users can create a new copy of the workbook, rename the workbook, move the workbook into a folder, or remove the workbook from their list of available workbooks. 

Sample workbooks

Sample workbooks are designed to help users become acclimated with the Exposure Time Calculator (ETC) and various instrument modes. This can include basic point source imaging for utilizing sensitivity calculations of each JWST instrument, imaging with multiple extended sources, coronagraphic imaging, slitted spectroscopy, and IFU calculations. 

Example science program workbooks

These workbooks are associated with the example science programs, which present realistic science programs for users to explore the steps in creating a proposal from scratch. These include observations of stars, galaxies, and Solar System targets with the full range of observing modes. ID numbers in the titles of each workbook are provided for easy matching of JDOX articles, ETC workbooks, and APT files for each example science program.

Getting started

From the Available Workbooks pane, click the SAMPLE WORKBOOKS or EXAMPLE SCIENCE PROGRAM WORKBOOKS button to obtain a list of pre-made workbooks. Once a workbook of interest is clicked, an independent copy is added to a user's list of available workbooks. To access the workbook, click Load. The user can then modify these workbooks for their own ETC calculations. The sample workbooks that have been copied are independent copies, so modifying them does not affect the master workbook. Users can always go back to the landing page and get another copy of the sample workbook provided with the ETC. When a workbook is opened, it is on the Calculations tab by default. There are pre-defined scenes and sources already available, and they have been created to illustrate the features that are most relevant to the observing mode with the given instrument. Note that any given workbook (for example, with slitless spectroscopy calculations) contains calculations for different instruments that allow that specific observing mode. In the case of the sample workbooks, the Calculations tab has a Notes pane at the bottom explaining each calculation.

Out-of-date workbooks

Figure 2. Out-of-date workbooks 

During a new ETC release, the workbooks from the previous ETC version that have been migrated to the current ETC are marked with a previous version number in the Ver column (as seen in Figure 2 above).

When you load the old workbook, it will open in "Read-only" mode. This ensures that the results from the previous version are not overwritten and will be retained for reference.

To update your old workbooks and work with them in the current ETC:

  • Identify the workbook you want to use from the list of available workbooks.
  • Click Load to open the read-only version of the old workbook.
  • Click Copy on the right-hand side of the row that contains the workbook. This creates an exact copy of the selected workbook and appears on the list of available workbooks.
  • Click Load to open the copied workbook in a separate browser tab.
  • All the calculations in the workbook will be automatically updated using the current version of the ETC software.
  • Compare the new results with those of the previous ETC version in the other tab.


JWST Exposure Time Calculator Tool

Pontoppidan, K. M., Pickering, T. E.,  Laidler, V. G.  et al., 2016, Proc. SPIE 9910, Observatory Operations: Strategies, Processes, and Systems VI, 991016
Pandeia: a multi-mission exposure time calculator for JWST and WFIRST

Notable updates
     Video link added.
Originally published