# Installation

## Setting up ``pandeia``

``pandeia`` is the ``python`` engine behind the JWST exposure time calculator
(ETC) [(Pontoppidan+ 2016)](https://ui.adsabs.harvard.edu/abs/2016SPIE.9910E..16P).
``jayrock`` uses it to simulate JWST observations locally on your machine.

``pandeia`` requires different reference datasets. Detailed install
instructions are [here](https://outerspace.stsci.edu/spaces/PEN/pages/77530136/Pandeia+Engine+Installation).
In short, you have to download three datasets and tell your system where to
find them by setting two system variables in your ``.bashrc`` or ``.zshrc`` (← Mac users) files.

1. JWST reference data (4GB) → [Section 3.1](https://outerspace.stsci.edu/spaces/PEN/pages/77530136/Pandeia+Engine+Installation#PandeiaEngineInstallation-RequiredData) of the instructions

:::{margin}
Lines starting with `$` are terminal commands.
:::

```{prompt} bash
export pandeia_refdata=/path/to/jwst_refdata/  # in your .bashrc or .zshrc file
```

2. Synphot datasets 5 (Phoenix models, 1.7GB) and 7 (JWST ETC spectra, 8.5MB) → [Section 3.2](https://outerspace.stsci.edu/spaces/PEN/pages/77530136/Pandeia+Engine+Installation#PandeiaEngineInstallation-RecommendedData>)

```{prompt} bash
export PYSYN_CDBS=/path/to/synphot_datasets/  # in your .bashrc or .zshrc file
```

:::{margin}

Getting the directory structure of the ``synphot`` datasets right can be tricky. For reference, this is what it looks like on my system:

```bash
$ export pandeia_refdata=$HOME/astro/data/pandeia  # line in my .zshrc file
$ export PYSYN_CDBS=$HOME/astro/data/synphot  # line in my .zshrc file
$ ls $PYSYN_CDB
comp  grid  grp
$ ls $PYSYN_CDBS/comp
acs  cos  fgs  foc  fos  hrs  hsp  nicmos  nonhst  ota  stis  wfc3  wfpc  wfpc2
$ ls $PYSYN_CDBS/grid
atmo2020  brown19  comp_qso  novae  phoenix  pne  solsys  stellar_pop  swire
$ ls $PYSYN_CDBS/grp
redcat
```
:::


## Installing ``jayrock``


``jayrock`` requires ``python`` 3.11 or higher. Install it via

```{prompt} bash
pip install jayrock
```

This will also install all required dependencies, including common ones like ``numpy``, ``pandas``,
``astropy``, ``astroquery``, and less common ones like ``rocks``, the [client](<https://rocks.readthedocs.io) of the [SsODNet database](https://ssp.imcce.fr/webservices/ssodnet/) of minor body data, and ``jwst_gtvt``, the [JWST General Target Visibility Tool](https://jwst-docs.stsci.edu/jwst-other-tools/jwst-target-visibility-tools/jwst-general-target-visibility-tool-help>).

After installing ``jayrock``, you can check that it installed correctly by running

```{prompt} python >>>
import jayrock
```

On your first run of a ``jayrock`` script, ``rocks`` might ask to [download data to a cache directory](https://rocks.readthedocs.io/en/latest/ssodnet.html#data-stored-on-your-machine>).
Confirm by typing ``y`` and pressing enter.