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R. M. Kippen J. Ryan A. Connors M. McConnell C. Winkler L. O. Hanlon V. Schönfelder J. Greiner M. Varendorff W. Collmar W. Hermsen L. Kuiper 《Astrophysics and Space Science》1995,231(1-2):231-234
In its first three years of operation, the COMPTEL instrument on theCompton Gamma-Ray Observatory has measured the locations (mean accuracy 1°) and spectra (0.75-30 MeV) of 18 gamma-ray bursts and continues to observe new events at a rate of 1/month. With good angular resolution and sensitivity at MeV energies, the growing COMPTEL burst catalog is an important new piece of evidence in the on-going GRB mystery. The COMPTEL burst locations are consistent with an isotropic distribution of sources, yet the spatial coincidence of two of the bursts indicates the possibility of repetition. The COMPTEL burst spectra are in most cases consistent with a single power law model with spectral index in the range 2–3. However, two bursts show evidence of a spectral break in the MeV range. Measurement of rapid variability at MeV energies in the stronger bursts provides evidence that either the sources are nearby (within the Galaxy) or the gamma-ray emission is relativistically beamed. We present an overview of analysis results obtained from the COMPTEL burst catalog concentrating on the search for burst repetition and the implications of highly variable MeV emission. 相似文献
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Amati L. O’Brien P.T. Götz D. Bozzo E. Santangelo A. Tanvir N. Frontera F. Mereghetti S. Osborne J. P. Blain A. Basa S. Branchesi M. Burderi L. Caballero-García M. Castro-Tirado A. J. Christensen L. Ciolfi R. De Rosa A. Doroshenko V. Ferrara A. Ghirlanda G. Hanlon L. Heddermann P. Hutchinson I. Labanti C. Le Floch E. Lerman H. Paltani S. Reglero V. Rezzolla L. Rosati P. Salvaterra R. Stratta G. Tenzer C. 《Experimental Astronomy》2021,52(3):183-218
Experimental Astronomy - THESEUS, one of the two space mission concepts being studied by ESA as candidates for next M5 mission within its Comsic Vision programme, aims at fully exploiting Gamma-Ray... 相似文献
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In recent years, a buoyant global market for minerals has led to renewed interest in the mining sector as a means of generating
economic growth in resource producing areas of developed nations. The development of new operations, however, raises concerns
around the impacts of mining activities on the environment, health and traditional ways of life of Indigenous peoples. Using
the proposed expansion of the Kemess mine in northern British Columbia as a case study, this paper examines two First Nations’
perspectives regarding the regulatory process through which environmental values may be validated and protected, and seeks
to understand how these First Nations’ environmental values and perceptions of risk are connected to health and well-being.
Sixteen key informant interviews were carried out and thematically analyzed through political ecology and environmental justice
frameworks. The paper argues that accommodating First Nations’ environmental values and perceptions of risks is a necessary
first step to reclaim health and well-being in politically marginalized settings. 相似文献
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L. O. Hanlon K. Bennett T. Galama T. A. Th. Spoelstra 《Astrophysics and Space Science》1995,231(1-2):307-310
The COMPTEL instrument onboard theCompton Gamma-Ray Observatory imaged the bright gamma-ray burst GRB 940301 within 1.6 hours of the event, with a mean 1 error radius of 1.5°. The error region was subsequently refined by combining the COMPTEL location with the arc derived from differences in the event arrival time at the Ulysses and BATSE detectors. Westerbork observations of the COMPTEL error region began on March 4 1994 at 21 cm, however coverage of the refined position was not obtained until 32 days after the GRB occurrence, by which time the operating wavelength had changed to 92 cm. We have constrained the level of variability of sources within the triangulation arc-COMPTEL 2 error box region to be less than 40 mJy (5 upper limit) at 92 cm 41 days after the burst. 相似文献
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Peter von Ballmoos Jose Alvarez Nicolas Barrière Steve Boggs Andrei Bykov Juan Manuel Del Cura Velayos Filippo Frontera Lorraine Hanlon Margarita Hernanz Emmanuel Hinglais Jordi Isern Pierre Jean Jürgen Kn?dlseder Lucien Kuiper Mark Leising Beno?t Pirard Jean-Pierre Prost Rui M. Curado da Silva Tadayuki Takahashi John Tomsick Roland Walter Andreas Zoglauer 《Experimental Astronomy》2012,34(2):583-622
DUAL will study the origin and evolution of the elements and explores new frontiers of physics: extreme energies that drive powerful stellar explosions and accelerate particles to macroscopic energies; extreme densities that modify the laws of physics around the most compact objects known; and extreme fields that influence matter in a way that is unknown on Earth. The variability of these extreme objects requires continuous all-sky coverage, while detailed study demands an improvement in sensitivity over previous technologies by at least an order of magnitude. The DUAL payload is composed of an All-Sky Compton Imager (ASCI), and two optical modules, the Laue-Lens Optic (LLO) and the Coded-Mask Optic (CMO). The ASCI serves dual roles simultaneously, both as an optimal focal-plane sensor for deep observations with the optical modules and as a sensitive true all-sky telescope in its own right for all-sky surveys and monitoring. While the optical modules are located on the main satellite, the All-Sky Compton Imager is situated on a deployable structure at a distance of 30?m from the satellite. This configuration not only permits to maintain the less massive payload at the focal distance, it also greatly reduces the spacecraft-induced detector background, and, above all it provides ASCI with a continuous all-sky exposure. 相似文献
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C. Winkler K. Bennett L. O. Hanlon K. S. O'Flaherty O. R. Williams R. M. Kippen J. Ryan W. Collmar V. Schönfelder H. Steinle W. Hermsen 《Astrophysics and Space Science》1995,231(1-2):153-156
COMPTEL on board CGRO has observed a very strong (S[> 0.3 MeV] = 2.03 × 10–4 erg cm–2), complex, and long lasting (162 s) gamma-ray burst on February 17, 1994 (GRB 940217). Temporal fluctuations occur on timescales as short as 100 ms. Hard-to-soft spectral evolution has been observed during the burst emission and also within individual peaks. The photon spectra obtained within the 6 peaks can be modelled by single power law spectra and by broken power laws with break energies at around 1 MeV. The best-fit power law slopes vary between 1.1 and 3.5 throughout the event. The burst is located at [
2000,
2000] = [29.5°, 3.8°] with a 3 error radius of 0.9°. COMPTEL does not detect any significant post-burst emission (as reported by EGRET) at low energies (< 30 MeV), and our upper limits are marginally consistent with the EGRET detections. Using high energy spectral and temporal information, distance limits to GRB 940217 have been derived. 相似文献
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L. O. Hanlon K. Bennett O. R. Williams C. Winkler R. D. Preece 《Astrophysics and Space Science》1995,231(1-2):157-160
Although the earliest observed gamma-ray burst spectra were well described by thermal bremsstrahlung models, subsequent observations above 1 MeV showed the existence of high energy power law tails in 60% of events. In order to accurately characterise burst spectra, both the low energy turnover and the high energy tail must be accounted for. We have addressed this issue by jointly deconvolving spectra obtained by BATSE and COMPTEL onboard theCompton Observatory. We present preliminary results obtained by application of this method to the gamma-ray burst of February 17, 1994. 相似文献
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Equipped to deal with uncertainty in climate and impacts predictions: lessons from internal peer review 总被引：1，自引：0，他引：1
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