Please note that this is Dominic Ford's personal copy of the 4GP code. It is basically a frozen copy of how the code stood in April 2019, when Dominic stopped working for 4MOST. The up-to-date code is in the official 4MOST IWG7 repository here: https://github.com/4most-iwg7/4most-4gp-scripts

The text on this page is a brief introduction to 4most-4gp-scripts. For a more complete tutorial, please visit the Wiki.

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.

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

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.

Before installing the scripts in this repository, you must have installed the Python modules contained in the 4most-4gp repository. If you have not already done this, you should read the associated wiki pages.

Once you have done this, you should check out the contents of this repository using the command:

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

When you install 4most-4gp-scripts, many of the scripts need to be able to locate tools such as Turbospectrum and 4FS which you installed as part of the 4GP installation process, and which they depend upon.

By far the simplest approach is if you install 4most-4gp-scripts alongside all the tools in the same directory where you keep your working copy of 4most-4gp. Thus, after installing various tools, this directory might look as follows:

dcf21@astrolabe:~/iwg7_pipeline$ ls
4most-4gp                  downloads         idl_packages    rvspecfit
4most-4gp-scripts          forwardModelling  interpol_marcs  sme
4most-iwg7-pipeline-tests  fromBengt         OpSys           TheCannon
4MOST_testspectra          fromKeith         pepsi           turbospectrum-15.1
AnniesLasso                hot_stars         pyphot          virtualenv

This is the default place where 4GP looks to find each tool, and if they are installed in this way then you will not need to explicitly tell it where to look.

You are permitted to install these tools in a different location, but then you will need to pass configuration parameters to a number of 4GP's modules (usually called binary_path) to tell it where to find each tool.