Getting Started#

Most use cases for VSPEC involve this simple workflow:

  1. Write a configuration file. For example: my_config.yaml

  2. Run the model:

    • >>> import VSPEC

    • >>> model = VSPEC.ObservationModel.from_yaml('my_config.yaml')

    • >>> model.build_planet()

    • >>> model.build_spectra()

  3. Read the data and analyze.

Note

VSPEC must have some way to call the PSG API. We interface with PSG using the pypsg package. The easiest thing you can do is add to the top of your script import pypsg; pypsg.docker.set_url_and_run(). This will check if PSG is installed, start the container if necessary, and set the URL appropriately.

Note

If you have an API key for PSG you can set it using the pypsg package. In a terminal type $ python -c "import pypsg;pypsg.save_settings(api_key='YOUR_API_KEY')". This will save you key to ~/.pypsg/settings.json where it can be read safely in the future.

Warning

Never commit your API key to a public repository.

Configuration Files#

Because the model running portion is so straightforward, most of the ‘work’ comes from writing a good configuration file. These files are useful because they allow all the paramaters of a model to be set statically together, but they are nothing more than a YAML representation of a VSPEC.params.InternalParameters object. See the Inputs page for descriptions of every VSPEC parameter.

In general the files look like this:

header:
    [ simulation header ]
star:
    [ bulk star paramters ]
    ld:
        [ limb-darkening parameters ]
    spots:
        [ spot paramters ]
    faculae:
        [ facula paramters ]
    flares:
        [ flare parameters ]
    granulation:
        [ granulation parameters ]
planet:
    [ planet-specific parameters ]
system:
    [ system-specific parameters ]
obs:
    [ observation-specific parameters ]
inst:
    [ instrument-specific parameters ]
psg:
    [ PSG-specific parameters ]
gcm:
    [ GCM parameters ]

Running the Model#

As shown above, running a configured model is very easy.

import pypsg
pypsg.docker.set_url_and_run()

from VSPEC import ObservationModel
path = 'my_config.yaml'
model = ObservationModel.from_yaml(path)
# run the model
model.build_planet()
model.build_spectra()

The simulated observation will now be saved to a local directory specified in the header. Except in cases where the Header is custom written by the user (i.e. not constructed from a YAML file), all simulation output is stored in a directory called .vspec.

Reading the Data#

VSPEC data is stored in the popular .fits format, however, we have included a built-in analysis class for convenience. This PhaseAnalyzer object reads in the final data products, which already live in the directory model.dirs['all_model'].

from VSPEC import PhaseAnalyzer
data = PhaseAnalyzer(model.directories['all_model'])

See the End-to-End Examples page for real use cases.