The Interplanetary Network Supplement to the BATSE Catalogs of Untriggered Cosmic Gamma‐Ray Bursts

We present Interplanetary Network (IPN) detection and localizationinformation for 211 gamma-ray bursts (GRBs) observed as untriggered events bythe Burst and Transient Source Experiment (BATSE), and published in catalogs byKommers et al. (2001) and Stern et al. (2001). IPN confirmations have beenobtained by analyzing the data from 11 experiments. For any given burstobserved by BATSE and one other distant spacecraft, arrival time analysis (or``triangulation'') results in an annulus of possible arrival directions whosehalf-width varies between 14 arcseconds and 5.6 degrees, depending on theintensity, time history, and arrival direction of the burst, as well as thedistance between the spacecraft. This annulus generally intersects the BATSEerror circle, resulting in a reduction of the area of up to a factor of ~650.When three widely separated spacecraft observed a burst, the result is an errorbox whose area is as much as 30000 times smaller than that of the BATSE errorcircle. Because the IPN instruments are considerably less sensitive than BATSE, theygenerally did not detect the weakest untriggered bursts, but did detect themore intense ones which failed to trigger BATSE when the trigger was disabled.In a few cases, we have been able to identify the probable origin of bursts assoft gamma repeaters. The vast majority of the IPN-detected events, however,are GRBs, and the confirmation of them validates many of the proceduresutilized to detect BATSE untriggered bursts.Comment: Minor revisions. Accepted for publication in the Astrophysical Journal Supplement Series, February 200