Second GBM TGF Catalog

Table of TGFs, TEBs and WWLLN Associations

First GBM TGF Catalog

First release, 2015 January 22

Primary Table
Triggered TGFs Table

These tables contain the data of the first GBM TGF catalog. The catalog contains 2704 TGFs, detected from GBM trigger enable on 2008 July 11 to 2014 July 31. The catalog is the result of the efforts of the GBM TGF Team.

Several method detected these TGFs, with increasing sensitivity with time. The initial method was in-flight detection using only the GBM NaI detectors, proceeding to in-flight detection also using the GBM BGO detectors, then to an offline search using time-tagged event (TTE) data. No TGF detection method has ever been removed. The time-tagged event data allows searching for TGFs at higher temporal resolution than possible in orbit and thus a much higher detection rate. Originally the TTE data was collected for portions of the orbit of Fermi, switching on 2012 Nov 26 to continuous production (CTTE).

There are a few TGFS with missing values (which are denoted with "NULL"), typically because of problems with the data files. As we are able to obtain these values, or if corrections are needed, updated tables will be posted.

The primary table has parameters for all 2704 TGFs. The table is in CSV format. The items in this table are:

  1. identification string, which is a date code "yymmddfff". "fff" is the fraction of the day. If two TGFs otherwise would have the same ID, a letter suffix is added.
  2. MET: GBM Mission Elapsed Time, the number of seconds since the reference time of January 1, 2001, at 0h:0m:0s in the Coordinated Universal Time (UTC) system. The value is the start time of the "discovery bin". The "discovery bin" is the interval for which the search program found the highest statistical significance.
  3. The name of the TTE FITS file with data for this TGF.
  4. The counts recorded by BGO detector 0 within the "discovery bin".
  5. The counts recorded by BGO 1.
  6. The counts of the NaI detectors, summed.
  7. The UTC date of the TGF.
  8. The UTC time of the start of the discovery bin.
  9. The width of the discovery bin in ms.
  10. The corrected, joint Poisson probability of the event. See Briggs et al., 2014.
  11. The WGS84 longitude of Fermi at the time of the TGF,
  12. The WGS84 latitude of Fermi,
  13. The WGS84 altitude of Fermi, in km.
  14. The local solar time, as fraction of a day.
  15. If this TGF was detected in-orbit as a trigger, the "Trigger ID". This item is the second item in the Trigger Table and may be used to cross-index the two tables.

The Triggered TGFs table contains the 476 TGFs that were detected in-orbit by the GBM flight software. The table is in CSV format. Triggered TGFs are associated with TGFs found by the ground search if the discovery bin of the ground search TGF starts within 18 ms of the trigger time (i.e., end time of 16 ms interval) of the triggered TGF. The items in this table are:

  1. Count of the triggered TGFs.
  2. Trigger ID, which is a date code "yymmdd.fff". "fff" is the fraction of the day.
  3. MET: GBM Mission Elapsed Time, the number of seconds since the reference time of January 1, 2001, at 0h:0m:0s in the Coordinated Universal Time (UTC) system. The value is the end time of the 16 ms interval in which the GBM flight software detected the TGF.
  4. The UTC date of the TGF.
  5. The UTC time of the end time of the 16 ms interval.
  6. The WGS84 longitude of Fermi at the time of the TGF,
  7. The WGS84 latitude of Fermi,
  8. The WGS84 altitude of Fermi, in km.
  9. The flight software algorithm by which the TGF was detected.
  10. The significance of the detection, as signal-to-noise ratio.
  11. The local solar time, as fraction of day.
  12. The local solar time, as hours and minutes.
  13. The ID of TGF as found by the ground search. This is the first item in the primary table and may be used to cross index the two tables. A few triggers had more than one detection by the ground search -- these IDs are separated by colons. A few triggered TGFS are not detected with the criteria used by the ground search (typically because one BGO detector has less than four counts), these have "NULL" as the ID.

A paper describing this catalog will be prepared. Until then, relevant information is provided by Gamma-ray Flashes in the Fermi era: Improved Observations and Analysis Methods. M. S. Briggs, et al., J. Geophys. Res., 118, 3805, 2014.

For questions contact Michael Briggs