Variable description

The following table provides a description to all the variables that are listed in the GRB summary table.

Variable Type Units Description
GRB_name string GRB name in the 'GCN' format, i.e. GRB010513B is the second GRB on the 13th of May 2001.
If the GRB_name is followed by an asterisk (*), then the GRB does not appear with a GCN-style name in the literature. These GCN-style names were hence auto-generated by GRBweb. Please refer to these GRBs using the corresponding Fermi or BATSE name.
GRB_name_Fermi string GRB name in the 'Fermi' format, i.e. GRB010513456 occurred on the 13th of May 2001, roughly 86400*0.456 seconds after midnight.
T0 double seconds Earliest UTC time at which activity was reported from the GRB. This time corresponds to the earliest trigger time of the satellites or the start of the T90 interval if it preceeds those trigger time. Times are displayed in the h:m:s format on the webpage and stored in seconds in the SQL catalog.
t_trigger double seconds UTC time at which the GRB triggered the satellite. Times are displayed in the h:m:s format on the webpage and stored in seconds in the SQL catalog.
ra double degrees Right ascension in J2000 coordinates. If the GRB was observed by multiple instruments, the localisation with the smallest angular uncertainty is used.
decl double degrees Declination in J2000 coordinates. If the GRB was observed by multiple instruments, the localisation with the smallest angular uncertainty is used.
pos_error double degrees 1σ error on the localisation. A 2d Gaussian pdf is assumed, implying that the probability that the true position of the GRB lies within 1σ degrees is ~39.3%.
T90 double seconds Duration of the time interval during which 90% of the GRB photon counts are observed, starting at 5% and ending at 95%. This parameter depends on the efficiency with which photons of various energies can be observed, making the T90 dependent on the detector.
T90_error double seconds Estimated 1σ error on the duration of the T90 interval.
T90_start double seconds UTC time that marks the start of the T90 interval.
fluence double erg/cm² The time integrated total energy per unit surface. Please note that the observed value strongly depends on the energy band and thus the detector that observed the burst.
  • For the Fermi-GBM detector, the energy band is 10-1000 keV.
  • For the Swift (BAT) detector, the energy band is 15-150 keV.
  • For the BeppoSAX detector, the energy band is 40-700 keV.
  • For the BATSE detector, the energy band is 20-300 keV.
fluence_error double erg/cm² Estimated 1σ error on the fluence.
redshift double Distance to the GRB.
'T100' double seconds Total time during which the GRB was observed. In practice, this variable is obtained by subtracting the earliest trigger time from the latest end of the T90 intervals.
GBM_located bool Indicates whether the localisation (ra, decl) was provided by the Fermi-GBM detector. As the uncertainty on bursts localized by the GBM is in general ill described by a 2d Gaussian pdf, we advice using the healpix priors provided by the GBM team for those bursts instead.
mjd (t_trigger) double days For conveniance, the value of 't_trigger' is also given in the 'Modified Julian Date' format. Please note that the values are in UTC and not in UT1. Due to leapsecond corrections, these two time standards can differ up to one seconds, making their distinction important especially in the case of short GRBs.
'variable'_source double days The source (catalog, circular, ...) from which the numerical value of the variable was extracted. Naturally, this column is only available in the Summary table where the data from all resources is grouped per GRB. Variable can be t_trigger, ra, redshift, etc.