BATSE 4B Duration Table Description

The DURATION Table contains values for T90 and T50, quantities related to burst duration, for 1234 gamma-ray bursts that triggered the BATSE LAD detectors between April 1991 and 29 August 1996. T90 measures the duration of the time interval during which 90% of the total observed counts have been detected. The start of the T90 interval is defined by the time at which 5% of the total counts have been detected, and the end of the T90 interval is defined by the time at which 95% of the total counts have been detected. T50 is similarly defined using the times at which 25% and 75% of the counts have been detected. T90 and T50 are calculated using data summed over the 4 LAD discriminator channels and using data summed over only those detectors that satisfied the BATSE trigger criteria.

Users must note that T90 and T50 are not available for those bursts which suffer from data gaps during the event; the integration procedure inherently fails in these cases. However, visual estimates of the burst duration are provided in the BATSE Comments table for those bursts with sufficient data coverage. Users may also find other pertinent comments concerning the calculated value of T90 and T50 in the BATSE COMMENTS table, and it is highly recommended that the COMMENTS table be consulted before any distribution selected on T90 or T50 is used.

The DURATION Table is available for download.

The table has seven columns, defined as follows:

1. The BATSE trigger number. This number can be used for cross-referencing with other tables in this BATSE catalog.
2. T50.
3. Uncertainty in T50.
4. The start time of the T50 interval, relative to the trigger time. The trigger time can be found in the BASIC Table.
5. T90.
6. Uncertainty in T90.
7. The start time of the T90 interval, relative to the trigger time.

All columns are in units of seconds. The measurements for Trigger 148 were recalculated after errors in the 3B values were brought to our attention by Jay Norris.