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lightcurve of the first gamma ray burst

Gamma ray burst (GRB) astronomy started when the first event was recoded on July 2, 1967, by Vela 4a and 4b (see figure on the left). Since then many missions have flown experiments capable of detecting GRBs. The events collected by these older experiments are mostly available in paper copy, each containing a few ten to a few hundreds bursts. No systematic effort in cataloging of these bursts has been available. In some cases the information is unpublished and in others difficult to retrieve. The first major GRB catalog was obtained by GRO with the BATSE experiment. It contains more than 2000 bursts and includes homogeneous information for each of the burst.

With the imminent launch of Swift, the first Gamma-ray/X-ray mission dedicated to the study of the GRBs and their afterglows, the time seems right to create a comprensive catalog containing all the information currently available for these past GRBs.

GRBCAT has been created using publications that report lists of GRB detections since their discovery. These are mostly papers already published in refereed journals, unpublished papers, and PhD thesis presenting lists of GRBs. Publications reporting observation on individual burst were not included at this stage. GRBcat also includes compilation of bursts that were already present in the HEASARC database system. The list of publications and database tablea used to create GRBCAT is available in the references page.

It also includes for the most recent bursts information about the afterglow.

The GRBcat project is lead by Neil Gehrels in collaboration with Barbara Mattson, Lorella Angelini, and Kevin Hurley. Most of the information for GRBCAT were not available in electronic form and were manually created in computer form. Please contact the authors to report problem with the catalog.

Catalog content

For each of the bursts the literature and database tables were searched for a set of basic quantities: the time of the trigger, the duration, the flux, the fluence, and the position (or the geometry of the region that contains the position). These quantities are provided in GRBCAT as published in the literature. There are no standards as to how these quantities are reported and for example the duration definition is different for different catalogs as well as the units for the flux and/or fluence. To account for these differences, these quantities are layed out in the catalog using several fields (or parameters) as explained below.

Associated to the flux and fluence fields there are parameters reporting the energy range, over which the flux or fluence was measured, and their units. The catalog includes parameters that can hold up to four energy ranges for fluxes and fluences. The time of the trigger is reported using different time reference system or in some cases is not specified. The catalog includes a field that specifies the time reference system. The duration of the GRB is defined in literature and/or in the database table with different standards and this is represented in GRBCAT by three parameters each dedicated to a specific standard.

It was not always possible to find from the publication a complete set of these quantities for each burst. When that occurs the parameters are left not populated.

On the Positions

The major problem with GRBs is to obtain accurate positions to identify the counterpart so as to estimate the distance to these events. For GRO/BATSE the positions were reconstructed by using the different amplitudes of the events as they were detected in the 8 BATSE detectors with an accuracy of few degrees. These were after rapidly disseminated by the GRB coordinated network (GCN) to ground base observatories to look for optical flashes. The Interplanetary GRB network in existence since 1976 uses the arrival time of these events as detected from different satellites across the solar system to estimate accurate positions. It was with the start of Ulysses's operations (in 1990) working in tandem with a group of satellites that made possible a systematic collection of these events. The third interplanetary network, currently working with Ulysses, Konus-Wind, Mars Odyssey, HETE-2, and HESSI, is collecting ~1 burst every 10 days. BeppoSAX, using the WFC detector working in tandem with the GRBM, was the first that was able to get arcminutes position.

The position reported in literature are typically regions with complicated geometry. GRBCAT includes parameters that can described each of the geometry for these complicated regions. For each burst only the parameters appropriate for a specific region type are populated.

Catalog Completeness

GRBCAT contains 5585 GRBs from 1967 up to February 26, 2003. Bursts are considered different if they occur in a time interval larger than 5 minutes. Events related to the SGR are not included. The catalog is not complete. It does not include all the events seen by Ginga or BeppoSAX or HETE2 or INTEGRAL and for a given bursts not all the detections from different satellites and/or detector are included.

For Ginga we could not find a comprensive list of bursts in literature that reports the information currently included in GRBCAT. The burst detected by the BeppoSAX/WFC have been included however the list from the high energy detector gamma ray burst monitor are not included. Burst detected by HETE-2 as reported via the GCN are complete up to February 26, 2003 similarly for INTEGRAL. It is possible however that some of these missing bursts detected by Ginga or BeppoSAX are included in GRBCAT if they were also seen by other satellites.

In many cases the same GRB has been reported by several satellites and listed in several publications. GRBCAT has a separate entry for each of the publication that reports information on a specific bursts. This is the case for the bursts included for example by the IPN but not exclusively.

On the afterglows

As for the main catalog the observation reported for the afterglows were extracted from the literature and from the GCN circulars. There are information for afterglow searches of 97 individual bursts and a total of 1187 observations reported. For each observation a flux or level of detection is reported as well as the redshift if available. The reported observations do not mean to give the entire light curve of the GRB/afterglow but rather as a representation of the obsevations that have been made. For afterglow searches included are either the first successful observation (if there was one) or the first unsuccessful attempt (if no afterglow was detected by that particular telescope). There is one observation listed in the table for each waveband observed at each telescope. There have been 52 bursts observed in radio, mm and sub-mm wave band with 32 afterglows detected. In the IR, near-IR, and optical band 43 afterglows were detected out of 89 observed. In the high energy regime (EUV, X-ray) there have been observations of 46 bursts detected 36 afterglows.

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Last modified: Thursday, 19-Jun-2008 16:42:52 EDT