Jul 12 – 23, 2021
Europe/Berlin timezone

Gammapy: a Python Package for Gamma-Ray Astronomy

Jul 13, 2021, 12:00 PM
1h 30m


Poster GAI | Gamma Ray Indirect Discussion


Axel Donath


Gammapy is a community-developed, open source Python package for gamma-ray Astronomy, which is built on the scientific Python ecosystem Numpy, Scipy and Astropy. It provides methods for the analysis of gamma-ray data of many instruments including Imaging Atmospheric Cherenkov Telescopes, Water Cherenkov, as well as space based observatories.

Starting from event lists and a description of the specific instrument response functions (IRF) stored in open FITS based data formats, Gammapy implements the reduction of the input data and instrument response to binned WCS, HEALPix or region based data structures. Thereby it handles the dependency of the IRFs with time, energy as well as position on the sky. It offers a variety of background estimation methods for spectral, spatial and spectro-morphological analysis. Counts, background and IRFs data are bundled in datasets and can be serialised, rebinned and stacked.

Gammapy supports to model binned data using Poisson maximum likelihood fitting. It comes with built-in spectral, spatial and temporal models as well as support for custom user models, to model e.g. energy dependent morphology of gamma-ray sources. Multiple datasets can be combined in a joint-likelihood approach to either handle time dependent IRFs, different classes of events or combination of data from multiple instruments. Gammapy also implements methods to estimate flux points, including likelihood profiles per energy bin, light curves as well as flux and signficance maps in energy bins.

In this contribution we present an overview of the most recent features and user interface of Gammapy along with example analyses using H.E.S.S, Fermi-LAT and simulated CTA data.


gammapy; software; likelihood fitting; github; source detection; gamma ray; awesome; model fitting; maximum likelihood; spectral analysis; data analysis; python; astropy;

Subcategory Experimental Methods & Instrumentation
other Collaboration Gammapy

Primary authors


Fabio Acero (Université Paris-Saclay) Luca Giunti Jalel Eddine Hajlaoui (APC Paris) Bruno Khelifi (APC Paris) Cosimo Nigro (DESY Zeuthen) Maximilian Noethe (TU Dortmund) Laura Olivera-Nieto (Max Planck Institut fur Kernphysik) Fabio Pintore (INAF) Quentin Remy José Enrique Ruiz (Instituto de Astrofísica de Andalucía) Atreyee Sinha (LUPM, CNRS) For the Gammapy collaboration

Presentation materials