Recent COMPTEL Burst Results

Information on the Latest COMPTEL Bursts --- GRB 990915

Archival Burst Images and Time Profiles

Latest All-Sky COMPTEL Burst Map --- [postscript]

Coincident Burst Pair Locations --- [postscript]

Gamma-Ray Burst Related Publications

COMPTEL Burst Capabilities

The COMPTEL instrument consists of two detector arrays. The upper detector is made of liquid scintillator (NE 213A) modules and the lower, NaI crystal modules. In the normal "Imaging Telescope" mode of opertation, cosmic gamma rays are detected by two successive interactions: a Compton scatter in the upper detector, then total absorbption in the lower. The locations of the interactions and energy losses in both detectors are measured. The accuracy in the measurement of these parameters determines the overall energy and angular resolution of the telescope. Data obtained by COMPTEL can be used to reconstruct burst source locations over a wide field-of-view (about 1-2 sr) with an accuracy of about 1-2 deg and determine burst energy spectra in the range 0.75-30 MeV. Each telescope "event" is time-tagged with an accuracy of 125 micro-seconds, allowing the study of rapid variability in burst time-profiles.

In addition to the normal double-scatter telescope mode of operation, two of the NaI crystals in the lower detector assembly of COMPTEL are operated simultaneously as burst detectors (see red modules in figure). These two modules are used to measure the time-profiles and energy spectra of gamma-ray bursts and solar flares. The burst detector modules are equipped with a dedicated electronic subsystem, the Burst Spectrum Analyzer (BSA). One of the burst modules provides energy coverage over a "low" range (~100 keV to ~1 MeV), and the other over a "high" range (~1 MeV to ~10 MeV). The burst detectors are sensitive to incident radiation over 4-pi steradians, though the field of view not obstructed by other portions of the spacecraft totals approximately 2.5 sr.

Ongoing COMPTEL Burst Projects

"BATSE/COMPTEL/NMSU Rapid Burst Response" program to search for fading burst counterpart emission at other (i.e., non gamma-ray) wavelengths using rapidly determined COMPTEL burst locations as a guide. A large rapid response network of optical and radio observatories is coordinated through our collaborators at New Mexico State University (NMSU).

Catalog of the locations and spectra of gamma-ray bursts detected by COMPTEL during the 4+ years of the Compton Gamma-Ray Observatory mission.

Spatial analysis of existing bursts localized by COMPTEL trying to answer the question of whether the observed GRB locations are consistent with an isotropic angular distribution of sources on all angular size scales.

Spectral analysis of existing bursts observed in both the "Telescope" and "Burst" modes of operation. The combined measurements cover a broad energy range extending from ~300 keV to ~30 MeV. Bursts are studied both individually (to examine spectral evolution, rapid variability, etc.) and collectively (to study global properties of MeV burst emission).



UNH High-Energy Astrophysics Group Directory

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Creation Date: Mon Jan 1, 1996