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About 4GP

4GP is the Galactic pipeline for the 4MOST multi-object spectrograph, developed by Infrastructure Working Group 7 (IWG7).

The pipeline comprises a collection of Python modules which use a common data format to store and manipulate spectra and their associated metadata. It makes it easy to pass spectra between a range of spectral synthesis, processing and analysis tools including Turbospectrum, the 4MOST Facility Simulator (4FS), and abundance analysis codes such as the Cannon, without the need for manual data format conversion.

It includes the ability to store spectra in libraries and search for them by arbitrary metadata constraints, making it easy to create new tests on subgroups of stars filtered from larger samples.

In addition, 4GP includes a simple web interface which allows the contents of spectrum libraries to be searched and viewed quickly for diagnostic purposes.

Code structure

The 4GP framework is available in two repositories on GitHub, and these Wiki pages provide step-by-step installation instructions. The first repository contains the Python modules which provide programmatic interfaces for creating and manipulating libraries of spectra. It includes wrappers for passing them to various analysis tools:

https://github.com/dcf21/4most-4gp

The second repository contains python scripts which utilise these modules to create command-line tools for synthesising spectra, manipulating them, and then testing abundance analysis codes such as the Cannon and the Payne on them:

https://github.com/dcf21/4most-4gp-scripts

Getting started

This code is under active development, but stable releases are periodically made.

Visiting the GitHub URLs above will present you with the master branch of our code, which should always correspond to the latest stable release. If you click on the "branches" dropdown menu, you can select a different version of the code to download.

Stable releases are given date stamps, for example, release-2019-03-01-1. The master branch points to the most recent release. The dev branch may contain experimental code and should be used with extreme caution.