This repository collects the material for the course on Gammapy.
These presentation and hand-on sessions are made during the school of the Astroparticle Physics Group at the São Carlos Institute of Physics of the University of São Paulo, during the period of February 17th to March 5th 2024.
- Introduction to Gammapy
- Installation and set-up
- First Hands-on: spectrum and 3D analysis
- Second Hands-on: data simulation
- Third Hands-on: estimation of systematic errors
During this presentation, Gammapy will be introduced. This open Python research software aims to analyse high-level data (under the GADF or OGIP formats) from gamma-ray instruments, like H.E.S.S/MAGIC/VERITAS/CTA (using the Imaging Atmospheric Cherenkov Technique) or HAWC/SWGO (using the Water Cherenkov Technique), as well as Fermi-LAT. This software permits the production of the common very-high-energy astrophysical products (like flux maps, spectral energy distribution, time domain analysis). This talk will describe the library based on its version v1.1, its main features and data flow, the organization of the Gammapy project.
Link towards the general Presentation: Gammapy Introduction.
A collection of links will help you for this course:
- The basic data structures can be discovered with this overview.
- The general web site of Gammapy is: https://gammapy.org/ .
- The documentation web site of Gammapy is: https://docs.gammapy.org/1.1/index.html .
- The GitHub repository of the Gammapy projet is: https://github.com/gammapy .
The version 1.1 of Gammapy will be used. See the Quickstart Setup of the documentation to install the Gammapy v1.1 environment. You need also to download the datasets as explained.
Finally, to get the tutorials for these hands-on gammapy sessions, you can clone this repository on your machine using
git clone https://github.com/bkhelifi/Brazil_2024.git
To access the tutorials:
cd Brazil_2024
jupyter lab
To update your directory on disk:
cd Brazil_2024
git pull
This first session aims to learn on your own laptop the basic uses of Gammapy, by using Jupyter Notebooks. We will work on the extraction of a spectrum from a point source, and on the realization of a 3D analysis of an extended source.
A full 1D (spectral) analysis tutorial from A to Z for a point-like extra-Galactic source.
Exercise about a full 3D analysis for an extended Galactic source. The solution will be seen together.
This lecture will focus on the simulations of data, which then permits to asset the performances of an instrument to a given source or to realize studies on reconstruction quality (assessment of systematics errors). We will firstly experience the simulations of a reduced binned dataset for a steady source and a time-variable object. The simulation of a full event list will be introduced at the end.
A full simulation tutorial from A to Z for an extented source having a power-law spectrum. The model parameters of the simulated dataset are retrieved.
- Exercise 1: retrieve the SkyModel parameters from the simulated dataset, compate them to the initial paramters, get the significance of the simulated source.
- Exercise 2: using simulations, determine the minimal time to detect significantly an exponential cut-off in the spectrum of a weak source
The last session will aim to quantify systematic errors using simulations. We will derive the errors on spectral parameters caused by a possible absolute energy scale bias or a possible background rate bias.