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STERNGRB: Help

STERNGRB - Stern et al. (2001) BATSE Gamma-Ray Burst Catalog


Overview

The Stern et al. (2001) BATSE Gamma-Ray Burst (GRB) Catalog was constructed by scanning the archival BATSE daily records (DISCLA data) covering the entire 9.1 years of BATSE's operation. 3906 GRBs were detected, 2068 of which are previously known BATSE triggers while 1838 of them are new non-triggered bursts. All events were detected in the same kind of data with 1.024 seconds time resolution and were processed with the same procedure, and thus constitute a uniform sample. This scan lowers the BATSE detection threshold to ~0.1 photons/s/cm**2.

Catalog Bibcode

2001ApJ...563...80S

References

Stern, B.E., Tikhomirova, Y., Kompaneets, D., Svensson, R. & Poutanen, J.
2001, ApJ, 563, 80.

Provenance

This database table was created at the HEASARC in August 2001 using the file ftp://ftp.astro.su.se/pub/head/grb/catalogs/etable2.txt on the Stockholm Observatory ftp site.

Parameters

Name
The designation of the gamma-ray burst based on the Truncated Julian Date (TJD) on which the GRB occurred plus an identifying letter preceded by the prefix "STK01" (for Stern, Tikhomirova, Kompaneets et al. 2001); this naming convention was adopted by the HEASARC in consultation with the authors.

Day_GRB
The Truncated Julian Date (TJD) on which the GRB occurred: TJD is related to Julian Date (JD) by TJD = JD - 2440000.5.

Seconds_GRB
The start of the GRB, in decimal seconds of the day given by the day_grb parameter. The start time is defined as the beginning of the first 1.024 s bin within the burst window where the fitted background was exceeded by 4 sigma in the 50-300 keV range. If there was no 4 sigma excess in 1.024 s bins, the procedure is repeated with 2.048 s, 4.096 s, 8.192 s bins. If the burst consists of a few widely spaced episodes, the GRB window covers the highest peak and does not necessarily coincide with the actual beginning.

Time
The start time of the GRB in the HEASARC standard time format. This parameter was created by the HEASARC based on the day_grb and seconds_grb parameters. The start time is defined as the beginning of the first 1.024 s bin within the burst window where the fitted background was exceeded by 4 sigma in the 50-300 keV range. If there was no 4-sigma excess in 1.024-s bins, the procedure is repeated with 2.048-s, 4.096-s, 8.192-s bins. If the burst consists of a few widely spaced episodes, the GRB window covers the highest peak and does not necessarily coincide with the actual beginning.

Trigger_Num
The BATSE Trigger Number of the GRB, or "1" if the GRB was a non-triggered event.

Peak_Flux
The peak flux in the 50-300 keV energy range, in photons/s/cm^2.

RA
The Right Ascension of the best-fit GRB location in the selected equinox: this was given in decimal J2000 degrees and with a precision of 0.1 degrees in the originating version of this catalog.

Dec
The Declination of the best-fit GRB location in the selected equinox: this was given in decimal J2000 degrees and with a precision of 0.1 degrees in the originating version of this catalog.

LII
The Galactic Longitude of the best-fit GRB location.

BII
The Galactic Latitude of the best-fit GRB location.

Error_Radius
The size of the 1-sigma confidence area, in degrees: this is further described in the Stern et al. (2001) paper as "the maximum distance from the best-fit location to the boundary of the 1-sigma area".

T90
The T90 duration of the event defined as the time interval between the emission of 5% and 95% of the total burst photon fluence, rounded to integer seconds. The value of T90 for weak short events is strongly affected by the Poisson noise and should be used with care. Poisson fluctuations cause an overestimation of T90 for such events. If N50 (the number of 1.024-s bins in the original DISCLA data in which the signal exceeds 50% of the peak value) is 1, the peak flux is below 0.5 photons/cm2/s and T90 is within 4 s, then this is probably a one-bin event with T90 < 1 s. Therefore, the catalog authors do not recommend using this duration distribution for a statistical analysis for bursts of durations less than a few seconds.

Num_Bins_50
The number of 1.024-s bins in the original DISCLA data in which the signal exceeds 50% of the peak value, or N50.

Kommers_Flag
A flag which is set to 1 to indicate an identification with an event listed in the Kommers et al. 1998 (K98) Catalog of Non-Triggered GRBs, else is set to 0. Flag equal to 1 means that the event exist in the K98 catalog. The agreement in the GRB location between the two catalogs is sometimes is very poor (difference up to 45 degrees). Stern et al. (2001) consider bursts to coincide if they overlap in time. If they differ in time by 100-300 s but have close locations, they consider such bursts identical as well.

Gap_Flag
A flag characterizing the data quality for the GRB with possible values as follows:

      0 = normal data
      1 = estimate of duration is problematic because of a data gap
      2 = estimate of the peak flux is problematic because of a data gap
      3 = 1 and 2 simultaneously
  

Contact Person

Questions regarding the STERNGRB database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
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