Fermi Science Support Center

GBM Data Products

The following tables list all the science data products created by the GIOC (the GBM's Instrument Operation Center) and provided to the FSSC. Some products are used by investigators in the Fermi-provided software, some are accessed by this software without the investigator's intervention, and others may be used by investigators independent of Fermi software.

A full description of the format of each data file can be found in the Science Data Products File Format Document.

Daily Data Products

The following data products are created daily by the GIOC and sent to the FSSC, regardless of whether a gamma-ray burst has been detected. These data products will be produced within 24 hours after the GIOC receives the last input data.

On 26 November 2012, the GBM flight software was updated to allow operation in a new data-taking mode. In nominal operation mode, the GBM is now continuously recording and sending to the ground time-tagged events (TTE) with 2 μs precision, synchronized to GPS once per second. This new operating mode produces continuous TTE files in addition to the snippets currently available around a GBM trigger. The previous 330-second window of the trigger TTE has been expanded to include more pre-trigger background and longer coverage post-trigger. Both trigger and continuous TTE files are provided through the HEASARC FTP site and via the Browse interface in the GBM Daily products. This continuous TTE mode will be throttled in selected (nominally, sun-facing) detectors at times of high solar activity to avoid telemetry volume problems at the spacecraft and mission operations level. During those times, the trigger TTE will also revert to the nominal 330-second window.

ID Name Description
GS-001 CTIME (daily version) The counts accumulated every 0.256 seconds in 8 energy channels for each of the 14 detectors.
GS-002 CSPEC (daily version) The counts accumulated every 8.192 seconds in 128 energy channels for each of the 14 detectors.
GS-003 TTE (continuous version) Event data for each detector with a time precise to 2 microseconds, in 128 energy channels. The downlink schedule determines how many data files are produced each day.
GS-005 GBM gain and energy resolution history History of the detector gains and energy resolutions; required for calculating Detector Response Matrices (DRMs).
GS-006 Fermi position and attitude history History of Fermi's position and attitude, required for calculating DRMs.

CTIME and CSPEC are PHA FITS files (i.e., files with a format that is standard for spectra), and therefore users may have software that accesses these files. The GS-005 and GS-006 data products will be accessed by Fermi software.

Trigger and Burst Data Products

The following data products are created by the GIOC and sent to the FSSC whenever a trigger has been detected, regardless of whether the trigger resulted from a gamma-ray burst (for example, a solar flare or an electron precipitation event may have caused the trigger). These data products have a latency of 1 day. Any of the products may be updated with new versions after the initial delivery. In particular, the catalog entry files (GS-105, GS-106, and GS-109) may be updated as trigger parameters are refined.

ID Name Description
GS-101 CTIME (burst version) For each detector, the counts accumulated every 0.064 s in 8 energy channels
GS-102 CSPEC (burst version) For each detector, the counts accumulated every 1024 s in 128 energy channels.
GS-103 GBM TTE (burst version) Event data for the burst. There is one file for each detector.
GS-104 GBM DRMs 8 and 128 energy channel Detector Response Matrices (DRMs) for all 14 detectors. These files may not be produced for all triggers.
GS-105 GBM Trigger Catalog Entry Classification of GBM trigger with some characteristics (e.g., trigger time, coordinates). This file is used to create the GBM Trigger Catalog.
GS-107 GBM TRIGDAT All the GBM's messages downlinked through TDRSS. These messages are the basis of the GCN Notices for the burst.
Quicklook Plots Lightcurves and spacecraft pointing history files in GIF and PDF format.

For triggers classified as gamma-ray bursts, the following products may also be available. The burst and spectral catalog entry files have longer latency than the other trigger files. The GS-109 spectral catalog entry files are only released when a new GRB catalog is published.

ID Name Description
GS-106 GBM Burst Catalog Entry Parameters describing the burst (e.g., durations, fluences). This file is used to create GBM Burst Catalog.
GS-109 GBM Spectral Catalog Entry Parameters describing the burst spectra (e.g., models and fits). The results are added to the GBM Burst Catalog.
GS-110 GBM Localization File Text file giving the right ascension and declination values corresponding to the chi-squared minima, 1σ, 2σ, and 3σ contours of the GBM localization. A PNG plot is also provided.

The Fermi software analyzes the TTE data (GS-103) using the response functions (GS-104) specific to a particular trigger.

Periodic Data Products

The following data products are created by the GIOC and sent to the FSSC from time to time.

ID Name Description Latency
GS-007 GBM PHA Look-Up Tables Tables of the correspondence between CTIME and CSPEC energy channels and the photopeak energy for each detector Every ~6 months
GS-009 GBM Low Level Threshold File Records periods of non-standard Low Level Threshold (LLT) operation. See the LLT Settings Page. Updated periodically
WWLLN Lightning Maps and Data files Maps of the lightning detections made by WWLLN and text data files with the positions and times of the lightning sferics on the maps. See the TGF Catalog Page. Updated periodically