| Archive | List of FERMI Catalogs |
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This table lists all of the triggers observed by one or more of the 14 GBM detectors (12 NaI and 2 BGO) which have been classified as gamma-ray bursts. Note that there are two Browse catalogs resulting from GBM triggers. All GBM triggers are entered into the Trigger Catalog, while only those triggers classified as bursts are entered in to Burst Catalog. Thus a burst will be found in both the Trigger and Burst Catalogs. The Burst Catalog analysis requires human intervention and so GRBs will be entered into the trigger catalog before the burst catalog. The latency requirements are 1 day for triggers and 3 days for bursts.
The GBM consists of an array of 12 sodium iodide (NaI) detectors which cover the lower end of the energy range up to 1 MeV. The GBM triggers off of the rates in the NaI detectors. These detectors are placed around the Fermi spacecraft with different orientations to provide the required sensitivity and FOV. The cosine-like angular response of the thin NaI detectors is used to localize burst sources by comparing rates from detectors with different viewing angles. To cover higher energies, the GBM also includes two bismuth germanate (BGO) detectors.
The signals from all 14 GBM detectors are collected by a central Data Processing Unit (DPU). This unit digitizes and time-tags the detectors pulse height signals, packages the resulting data into several different types for transmission to the ground (via the Fermi spacecraft), and performs various data processing tasks such as autonomous burst triggering.
The Fermi GBM Daily Data database table contains entries for each day for which GBM data has been processed.
The daily data products consist of GBM data that are produced continuously regardless of whether a burst occurred. Thus these products are the count rates from all detectors, the monitoring of the detector calibrations (e.g., the position of the 511 keV line), and the spacecraft position and orientation. The underlying Level 0 data arrive continuously with each Ku band downlink. However, the GBM Instrument Operations Center (GIOC) will form FITS files of the resulting Level 1 data covering an entire calendar day (UTC); these daily files are then sent to the GSSC. Consequently, the data latency is about one day: the first bit from the beginning of a calendar day may arrive a few hours after the day began while the last bit will be processed and added to the data product file a few hours after the day ended. These data products may be sent to the GSSC file by file as they are produced, not necessarily in one package for a given day.
Note that the data may include events from slightly before and slightly after the day official boundaries, which will be reflected in the start and stop times in the table. Consequently, some events may be listed in files for two consecutive days (e.g., at the end of one and the beginning of the next).
Due to the continuous nature of GBM processing, new data files may arrive after the day has been included in Browse and reprocessed version may also arrive at any time. The reprocessed data will have the version number incremented (see file name conventions below). Browse will automatically download the latest versions of the data files.
This table lists all of the triggers observed by one or more of the 14 GBM detectors (12 NaI and 2 BGO). Note that there are two Browse catalogs resulting from GBM triggers. All GBM triggers are entered into the Trigger Catalog, while only those triggers classified as bursts are entered in to Burst Catalog. Thus a burst will be found in both the Trigger and Burst Catalogs. The Burst Catalog analysis requires human intervention and so GRBs will be entered into the trigger catalog before the burst catalog. The latency requirements are 1 day for triggers and 3 days for bursts.
The GBM consists of an array of 12 sodium iodide (NaI) detectors which cover the lower end of the energy range up to 1 MeV. The GBM triggers off of the rates in the NaI detectors. These detectors are placed around the Fermi spacecraft with different orientations to provide the required sensitivity and FOV. The cosine-like angular response of the thin NaI detectors is used to localize burst sources by comparing rates from detectors with different viewing angles. To cover higher energies, the GBM also includes two bismuth germanate (BGO) detectors.
The signals from all 14 GBM detectors are collected by a central Data Processing Unit (DPU). This unit digitizes and time-tags the detectors pulse height signals, packages the resulting data into several different types for transmission to the ground (via the Fermi spacecraft), and performs various data processing tasks such as autonomous burst triggering.
The Fermi LAT table of monitored sources provides daily and weekly fluxes for sources of interest as described in http://fermi.gsfc.nasa.gov/ssc/data/policy/LAT_Monitored_Sources.html. In addition, similar information will be released for any source which flares above 2x10-6 photons cm-2 s-1 until the flux drops below 2x10-7 photons cm-2 s-1. Fermi is currently in survey mode and observes the entire sky every day. However if a source does not exceed the detection threshold, no entry will appear in the catalog.
The tabulated fluxes are derived at the LAT Instrument Science Operations center in a 'quick look' analysis to produce results quickly to facilitate follow-up multiwavelength observations of flaring sources. The table of released fluxes will be updated as analysis and calibrations improve.
These early flux estimates do not include systematic uncertainties and do not have an absolute flux calibration. Use of these data as absolute flux measurements for constraining models or for comparison to other data is strongly discouraged at this time. In addition to overall normalization uncertainties, source fluxes may have variations of up to 10% due to currently-uncorrected dependencies of the gamma-ray detection efficiency on variations of the particle background in orbit. Please note that these results are produced using preliminary instrument response functions and calibrations. The quality and stability of these results will improve when updated calibrations become available over the coming months.
The Fermi LAT table of bright sources is a list of bright LAT sources that have statistical significances of 10 sigma or higher, based on the first three months of survey data. The primary purpose of this list is to assist proposers for Guest Investigator Cycle 2 (due date 6 March). This list will eventually be superceded by the LAT Source Catalog, to be released about one year after launch.
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