摘要:

The past 20 years of gamma‐ray burst observations are summarized. Time history morphologies and durations are discussed, as well as continuum and line energy spectra. The results of statistical studies on the spatial distribution, logN(≳S)− log S, andV/Vmaxare presented, and the status of quiescent and transient counterpart searches are reviewed. A table of soon‐to‐be‐obsolete ‘‘Gamma‐ray Burst World Records’’ is given. Due to the presence of new ground‐based and space experiments, it seems likely that substantial progress in understanding this phenomenon will be made in the 90’s

ISSN:0094-243X    

DOI:10.1063/1.42772

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Gamma‐ray bursts are being detected with unprecedented sensitivity by the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray observatory since its launch in April, 1991. The experiment is detecting about one gamma‐ray burst per day. A brief description is presented of the on‐orbit performance of BATSE, the methods of identification of bursts, and examples of the diverse time profiles of the gamma‐ray bursts observed. The most significant finding thus far is the apparent isotropy of the bursts together with the observed inhomogeneity of the sources.

ISSN:0094-243X    

DOI:10.1063/1.42813

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The imaging &ggr;‐ray telescope COMPTEL on board NASA’s Compton Gamma‐Ray Observatory (GRO) has observed many cosmic gamma‐ray bursts during the early mission phase of GRO. COMPTEL records time‐resolved burst spectra over 0.1 MeV to 10 MeV energies, and, for the first time, produces direct single‐telescope gamma‐ray images (0.8–30 MeV) of cosmic gamma‐ray bursts occurring in its 1 sr field of field.

ISSN:0094-243X    

DOI:10.1063/1.42837

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

This short report presents the most recent results of GRB observations with the Ginga satellite. Since the launch of Ginga in 1987, three GRBs with the cyclotron spectral feature have been observed. Some of the observed GRBs exhibited precursor in the soft X‐ray energy band (1–10 keV) which preceded the main flash of gamma‐ray photons above several tens keV. These two topics are reported with figures.

ISSN:0094-243X    

DOI:10.1063/1.42796

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The Oriented Scintillation Spectrometer Experiment detected over 80 cosmic &ggr;‐ray bursts from mid‐April to late November, 1991. Data at 16 ms resolution were accumulated from its large‐area NaI shields in response to BATSE triggers. Rates in excess of 5000 cts/16 ms were observed from the 1991 May 3 burst. Bursts on June 1 and August 7 were observed in the spectrometer’s aperture. Preliminary information on both the spectrum and location of the source of the June 1 burst are provided. Plans for future observations and analyses of bursts are discussed.

ISSN:0094-243X    

DOI:10.1063/1.42804

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1, 2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

ISSN:0094-243X    

DOI:10.1063/1.42768

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The Granat satellite, launched into highly eccentric orbit on December 1, 1989, carries the Phebus experiment designed for cosmic and solar gamma‐ray burst spectroscopy in the 0.1–100 MeV energy range. The sensor system consists of six independent Bismuth germanate (BGO) detectors giving a large efficiency at high energy (each detector has a photopeak effective area of more than 20 cm2above 10 MeV). In 1990, the Phebus experiment observed 49 gamma‐ray bursts (GRB) with a large fraction (about 35%) of short duration events (less than 2 seconds). We compare here typical spectra of short and longer bursts with emphasis on the maximum energy and on the hypothetical existence of spectral features above 1 MeV.

ISSN:0094-243X    

DOI:10.1063/1.42776

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A number of gamma‐ray bursts (GRBs) have been detected by means of gamma‐ray detectors aboard three Air Force Defense Meteorological Satellite Program (DMSP) satellites, in polar orbits at 800 km altitude. The gamma‐ray data have a 2 s resolving time, and are usually telemetered in 5 energy bins in the range 50–1000 keV. Although it is not possible to detect GRBs when the DMSP satellites are passing through the radiation belt or the South Atlantic Anomaly, or when the source is obscured by the Earth, a number of GRBs have been detected by two or even three of the satellites. THE DMSP data may be of considerable assistance in evaluating time histories, locations, and spectra of GRBs.

ISSN:0094-243X    

DOI:10.1063/1.42777

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

After two years in orbit the WATCH instruments on the GRANAT space observatory have localized seven gamma burst sources with better than 1° accuracy. In several cases, follow‐up observations with Schmidt telescopes have been made within a few days. Some of the bursts have also been detected by the distant space probes PVO and ULYSSES and there are, therefore, good prospects for obtaining much improved positions using the burst arrival times. The existence of the almost concurrent Schmidt plates could then become particularly interesting.

ISSN:0094-243X    

DOI:10.1063/1.42778

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The spatial distribution of gamma‐ray burst source is investigated using the intensity distribution and the angular distribution and the angular distribution of bursts observed by BATSE. The intensity distribution exhibits fewer weak burst than would be expected for a homogeneous distribution of sources. However, the angular distribution is consistent with an isotropic distribution. These results are compared to galactic disk and halo models of gamma‐ray burst sources.

ISSN:0094-243X    

DOI:10.1063/1.42779

出版商:AIP    

年代:1991

数据来源: AIP