The Pandeia engine of the Exposure Time Calculator is released to the community to support users who wish to script their calculations, run more extensive parameter space studies, and have more direct control of their scenes.We also recognize that the community has developed more extensive wrappers and public tools that depend on the Pandeia engine.
This page is intended to facilitate communication with developers in the community with Pandeia engine dependencies.
The latest release of the Pandeia engine is 1.5.1.
- Get the latest engine release software, installable with pip
- See its installation instructions (presently Webb-specific)
- Get the optional data files that support certain target spectra manipulations
- Get the required mission-specific items:
| Webb | Roman |
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Next Planned Release
Version 1.5.2 is planned to release in late August 2020.
Important
- This version drops support for Python 2
Highlights include:
Code/Dependencies:
- The Pandeia Engine now uses synphot and stsynphot internally for spectral manipulation, replacing pysynphot. The external API has not changed.
- The Pandeia Engine is no longer compatible with Python 2. We recommend at least Python 3.6.
Data:
- General:
- Users will no longer need the optional data files to specify sources normalized in Vegamags
- JWST:
- Additional readout patterns are now available for the NIRSpec MOS Confirmation Imaging mode (mos_conf)
- Roman:
- The Nancy Grace Roman Space Telescope is still named "wfirst" internally, and its instrument is still called "wfirstimager"
- The wfirstimager "grism" mode has been renamed to "spectroscopy", and it now uses the "any" aperture (the "grism" aperture has been removed, resulting in a smaller reference data package)
- PSFs for the wfirstimager's "any" aperture have been regenerated with WebbPSF 0.9.0 (JWST PSFs remain the same as 1.5.1)
See draft release notes.
What support is available?
Questions about the Pandeia engine for Webb may be directed to the JWST help desk; for Roman, email help@stsci.edu with Roman and/or WFIRST in the subject line or body. However, due to the complexity of the engine, support will be limited and response times may be longer than for other tools.
We welcome comments and feature requests, and these will be considered along with other ETC work.
What is the Pandeia Engine?
The Pandeia engine uses a pixel-based 3-dimensional approach to perform calculations on small (typically a few arcseconds) 2-dimensional user-created astronomical scenes. It models both the spatial and the wavelength dimensions, using realistic point spread functions (produced using WebbPSF) for each instrument mode. It natively handles correlated read noise, inter-pixel capacitance, and saturation. Since the signal and noise are modeled for individual detector pixels, the ETC is able to replicate many of the steps that observers will perform when calibrating and reducing their JWST data. This simplifies interpretation of the extracted signal-to-noise ratio (SNR) calculated by the ETC.
Details on the algorithms used to compute signal and noise on the detector and the strategies used to compute the extracted products can be found in Pontoppidan et al. 2016.
