JWST ETC Calculations Page Overview

The JWST Exposure Time Calculator initializes a calculation once the user chooses an instrument and mode. Multiple calculations can be compared, copied, and modified in the ETC workbook. 

Video Tutorial:  ETC General Overview

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

The Calculations page in the JWST ETC is where a user specifies an instrument and mode, the background, instrument and detector configuration, and observing setup and extraction strategy for a given calculation. This is typically done after scene(s) and source(s) of interest have been defined on the Scenes and Sources page, although a default scene containing a central point source is always available. The Calculations page offers users the ability to do a comparative analysis of multiple sources or locations in the scene to determine which calculation offers the best signal-to-noise ratio (SNR). 

List of articles

  1. JWST ETC Creating a New Calculation: Instructions for setting up, editing, and running calculations in the ETC.
  2. JWST ETC Backgrounds: Description of the available background options including example positions, dated backgrounds, and percentile options.
  3. JWST ETC Wavelength of Interest: Explanation of the Wavelength of Interest/Wavelength of Slice option and how to make best use of it in ETC calculations.
  4. JWST ETC Batch Expansions: Details on the various batch expansion options that can be used for quick exploration of SNR for different filters and detector parameters.
  5. JWST ETC Strategies: Landing page with links to individual articles on all of the available extraction strategies in the ETC.
  6. JWST ETC Target Acquisition: Landing page with links to individual articles detailing target acquisition (TA) calculations with all 4 science instruments.
  7. JWST ETC Cosmic Ray Implementation: Description of how the ETC models the effects of cosmic ray strikes on calculation results.
  8. JWST ETC Saturation: Information on the types of saturation and full-well depths used in the ETC.
  9. JWST ETC Residual Flat Field Errors: Description of the effects of flat field errors in the ETC and mitigation techniques.
  10. JWST ETC Time-Series Modes: General and instrument-specific advice for using time-series modes in the ETC.
  11. JWST ETC Readout Patterns: Landing page with links to instrument-specific readout pattern information.
  12. JWST ETC NIRCam Coronagraphic Imaging: Description and walkthrough of the NIRCam Coronagraphic Imaging mode.

Latest updates
    Updated for ETC 3.0.

    Updated for ETC 1.5. Video link added.

  • Updated for ETC 1.3.
Originally published