1.1. For Pandeia Engine v2026.1 & v2026.7

Python Requirements:

Installing the Pandeia Engine requires a python environment with the dependencies listed above, a set of telescope-specific datafiles, and an optional (but highly recommended) second set of data files for additional spectral manipulation capabilities.

2. Code

The engine can be installed with

pip install pandeia.engine==2026.7

or for Roman:

pip install pandeia.engine==2026.1

Then set up the data files.

3. Data

3.1. Required Data

In order to function, the Pandeia Engine requires one (or for the more recent Roman release, two) set of reference data (containing instrument definitions):

• James Webb Space Telescope:
  • https://stsci.box.com/v/pandeia-data-v2026p7-jwst (20 MiB)
  • https://stsci.box.com/v/pandeia-psfs-v2026p7-jwst (4 GiB)
• Nancy Grace Roman Space Telescope:
  • https://stsci.box.com/v/pandeia-data-v2026p1-roman (17 MiB)
  • https://stsci.box.com/v/pandeia-psfs-v2026p1-roman (523 MiB)

Download and untar the files to a suitable location.

(looking for an older version of the ETC? Check the bottom of the page)

Environment variable:
$pandeia_refdata must point to the location of the top of the data file tree: the directory containing the VERSION_DATA file
$PSF_DIR must point to the location of the top of the psf file tree: the directory containing the VERSION_PSF file

• The base Synphot reference atlas. The Synphot reference atlases (https://archive.stsci.edu/hlsp/reference-atlases) are used to provide more spectroscopic functionality.

  • Only Synphot 1 (normalization bandpasses, HST bandpasses) is required: https://archive.stsci.edu/hlsps/reference-atlases/hlsp_reference-atlases_hst_multi_everything_multi_v16_sed.tar

Once untarred, the files will produce a directory tree of grp/redcat/trds. The pandeia.engine uses the contents of the trds directory.

3.2. Recommended Data

The rest of the Synphot datasets are optional and enable specific classes of template spectra.

• Synphot 2 (Stellar and Galactic Model Files - brown2014, pickles, bz77)
• Synphot 3 (Castelli & Kurucz 2004 Atlas  - ck04models)
• Synphot 4 (Kurucz 1993 Atlas - k93models)
• Synphot 5 (Phoenix models - phoenix)
• Synphot 7 (JWST ETC Spectra - atmo2020, brown2019, comp_qso, swire, novae, stellar_pop, solsys, pne)

Once untarred, the files will produce a directory tree of grp/redcat/trds. The pandeia.engine uses the contents of the trds directory.

Environment variable: $PYSYN_CDBS must point to the trds directory (NOT grp)

4. Verify Installation

Open up a terminal with access to the conda installation, and type

python -c "import pandeia.engine; pandeia.engine.pandeia_version()"

If properly installed and configured, it should show the refdata version and synphot data directory, like this:

Pandeia Engine version:  2026.7
Pandeia RefData version: 2026.7
Pandeia PSFs version:    2026.7
Pysynphot Data:  /your/data/directory/synphot

or for Roman:

Pandeia Engine version:  2026.1
Pandeia RefData version: 2026.1
Pandeia PSFs version:    2026.1
Pysynphot Data:  /your/data/directory/synphot

5. Helper Script

The following script (which can also be added to your .bashrc or .bash_profile file) assumes you are operating in a BASH shell where a python installation has been installed and activated, that you've installed the pandeia refdata in ${HOME}/data/pandeia, the pandeia PSF library in ${HOME}/data/pandeia_psfs, and the cdbs folder from the additional dataset moved and renamed to ${HOME}/data/synphot

#!/bin/sh
export PYSYN_CDBS=${HOME}/data/synphot
export pandeia_refdata=${HOME}/data/pandeia
export PSF_DIR=${HOME}/data/pandeia_psfs

Once in place, "source"ing this file will set up the pandeia environment.

6. Old Versions