Fermi Gamma-ray Space Telescope

GBM Software Tools

Gamma-ray Data Tools

The Gamma-ray Data Tools (GDT) is an open-source Python-based centralized toolkit for analyzing data from space-based hard X-ray and gamma-ray instruments. The GDT borrows its heritage from, and supersedes, the Fermi GBM Data Tools. The GDT is designed with a "core" package that contains generalized functionality and base classes that are utilized by a variety of mission packages. Currently, the GDT family includes the Fermi/GBM, CGRO/BATSE, HETE-2/FREGATE, INTEGRAL/SPI-ACS, MAXI/GSC, RXTE/ASM, and Swift/BAT packages. Current planned additions to the GDT family include Suzaku/WAM, BurstCube, Glowbug, and StarBurst. Previous users of the Fermi GBM Data Tools will find several advantages to using the GDT, including additional functionality, bug fixes, and the newly released GBM localization algorithm. Community contributions are welcome to any of the GDT packages in the form of bug fixes, new features/requests, documentation/tutorial improvements, API improvements, and new mission packages, and guidelines for community contributions are available in the documentation. The GDT is partially funded by NASA ADAP grant 80NSSC21K0651; NASA SMD Open Source Tools, Frameworks, and Libraries grant 80NSSC22K1741; and NASA Astrophysics ISFM proposal number 22-A22ISFM-0005 for continued development and support.

GBM Data Tools

Note: The GBM Data Tools have been superseded by the Gamma-ray Data Tools.

The GBM Data Tools allow users to read, reduce, and visualize GBM data with only a few lines of Python code and to incorporate GBM analysis into their scripts and workflows without having to sweat very many details. For expert users and users who want fine control over various aspects of their analysis, the Data Tools also exposes a lower-level API (Application Programming Interface) layer, which can also be used to generalize the GBM Data Tools to data from other similar instruments.


Prior to the launch of Fermi, the GBM team developed a GUI-based spectral analysis software tool in IDL, called RMfit, specializing in the analysis of GBM trigger data. More than 10 years later, an open source, multi-wavelength approach is desirable, integrating with the long-standing community standard fitting engine, XSPEC. GSpec is a replacement of RMfit, implemented in Python, that allows analysis of GBM data via a user-interactive GUI similar to RMfit and additionally enables users to create their own Python scripts using the included libraries. GSpec provides a seamless interface to XSPEC and allows users to define additional data reduction techniques, such as background fitting/estimation and data binning, as Python-based plugins. It is part of a larger effort to produce a set of GBM data tools to allow the broader community to analyze all aspects of GBM data, including the continuous data that GBM produces.


Note: Rmfit is deprecated. Please use the Gamma-ray Data Tools instead.

The rmfit software package was developed by members of the gamma-ray astronomy group at the University of Alabama in Huntsville. It uses a forward-folding technique to obtain the best-fit parameters for a chosen model given user-selected source and background time intervals from data files containing observed count rates and a corresponding detector response matrix. rmfit displays lightcurves and spectra using a graphical interface that enables user-defined integrated or time-resolved spectral fits and binning in either time or energy. Originally developed for the analysis of BATSE Gamma-Ray Burst (GRB) spectroscopy, rmfit is a tool for the spectroscopy of transient sources. It has evolved considerably to accommodate the Fermi GBM and LAT data. Limited support is available for data from other instruments such as the Swift BAT. More information is available in the installation notes and accompanying tutorial.

You can install the GBM rmfit tool using the precompiled binary. The system requirements are:

Mac OS X 10.6 (Snow Leopard) to OS X 10.10 (Yosemite)


a machine with Linux or a Linux derivative

GBM Response Generator

The Fermi GBM team has provided a portable version of their response matrix generation software and associated calibration files. You will need about 2.5 GB of disk space to install the package. Previously, this software was available to the public only via an interactive web interface. The response file generator facilitates production of response files for a GBM triggered event or for an arbitrary source location at an arbitrary time for each of the GBM detectors. The intent is to better facilitate studies such as candidate, non-triggered GRBs or solar flares, TGFs and searches for electromagnetic counterparts to gravitational waves. We note that a set of standard, optimally generated, response matrices are archived and available for all triggered events and are recommended for use with those data.

GBM Detector-Only Model Files

The files NaiDetModelWithMLI_v2_20.gdml and BgoDetModel_v2_20.gdml contain models of the Fermi GBM NaI and BGO detectors, specified in Geometry Description Markup Language (GDML). These files may be used in GEANT4. The files only describe single detectors of each type; neither the Fermi spacecraft nor scattering of gamma-rays from the Earth's atmosphere are included. These files were formerly available from Los Alamos National Laboratory (LANL) and are now made available at the Fermi Science Support Center. They were produced by a team lead by GBM team member R. Marc Kippen.

References are:

  • Kippen, R. M., et al. 2007. "Instrument Response Modeling and Simulation for the GLAST Burst Monitor." In AIP Conf. Proc. 921, The First GLAST Symposium, eds. S. Ritz, P. Michelson, & C. Meegan (New York: AIP), p. 590.
  • Hoover, A. S., et al. 2008. "GLAST Burst Monitor Instrument Simulation and Modeling." In AIP Conf. Proc. 1000, Gamma-ray Bursts 2007: Proceedings of the Santa Fe Conference, eds. M. Galassi, D. Palmer, & E. Fenimore (New York: AIP), p. 565.