A5067827311- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Particle Accelerators and Free-Electron Lasers
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Radio Astronomy Observations and Technology
- Particle Detector Development and Performance
- Dark Matter and Cosmic Phenomena
- Nuclear Physics and Applications
- Galaxies: Formation, Evolution, Phenomena
- Particle physics theoretical and experimental studies
- Geophysics and Gravity Measurements
- Particle accelerators and beam dynamics
- Neutrino Physics Research
- High-pressure geophysics and materials
- CCD and CMOS Imaging Sensors
- X-ray Spectroscopy and Fluorescence Analysis
- Solar and Space Plasma Dynamics
- Knowledge Management and Sharing
- Digital Games and Media
- Wikis in Education and Collaboration
- GNSS positioning and interference
- Radiation Detection and Scintillator Technologies
Springer Nature (United States)
2018
SRON Netherlands Institute for Space Research
1994-2000
Leiden University
1994
The imaging Compton telescope COMPTEL aboard NASA's Gamma-Ray Observatory has opened the MeV gamma-ray band as a new window to astronomy. provided first complete all-sky survey in energy range 0.75 30 MeV. catalogue, presented here, is largely restricted published results. It contains firm well marginal detections of continuum and line emitting sources presents upper limits for various types objects. numbers most significant are 32 steady 31 bursters. Among sources, detected so far,...
The COMPTEL experiment aboard CGRO, exploring the previously unknown sky at MeV-energies, has so far detected 10 Active Galactic Nuclei (AGN): 9 blazars and radio galaxy Centaurus A. No Seyfert been found yet. With these results opened field of extragalactic Gamma-ray astronomy in MeV-band.
The EGRET experiment aboard the Compton Gamma-Ray Observatory (CGRO) has observed at energies above 100 MeV strong gamma-ray flares with short-term time variability from blazars 3C 279 [1] and PKS 1622-297 [2]. During these flaring periods both have been detected by COMPTEL CGRO photon of ∼10 MeV, revealing simultaneous γ-ray activity down to energies. For cases derived fluxes exceed those measured in previous observations, shows an indication for within observational period. Both sources...
We present first results of a systematic search through COMPTEL all-sky maps for evidence MeV gamma-ray emission from active galaxies. All-sky maximum-likelihood and flux have been produced publicly-available datasets individual CGRO viewing periods the 4.5-year period covering Phases 1 to 4 mission (1991–1995), in four standard energy bins spanning sensitive range (0.8–30 MeV). From these we extracted statistical likelihoods source corresponding fluxes or upper limits ∼150 candidate objects...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation O. R. Williams, K. Bennett, Much, V. Schönfelder, W. Collmar, H. Bloemen, J. Blom, Hermsen, Ryan; Further COMPTEL observations of the region around GRO J1753+57: are there several MeV sources present?. AIP Conf. Proc. 10 May 1997; 410 (1): 1243–1247. https://doi.org/10.1063/1.53935 Download citation file: Ris...
The maximum likelihood-ratio method is frequently used in COMPTEL analysis to determine the significance of a point source at given location. In this paper we do not consider whether particular location indicates detection, but rather distributions likelihood-ratios derived from many locations depart that expected for free data. We have constructed by reading values standard maximum-likelihood ratio maps positions corresponding different categories AGN. Distributions Seyfert galaxies are...
The COMPTEL experiment aboard the Compton Gamma-Ray Observatory (CGRO) has observed gamma-ray blazar 3C 279 several times between April 1991 and September 1995. This paper reports on a consistent analysis of these observations using most recent data tools. Detections non-detections along CGRO-mission indicate time-variable MeV-flux. Spectral variability is indicated as well, however can not be significantly proven by spectral fitting. average MeV-spectrum 279, measured over four-year period,...
The COMPTEL observations of the blazar-type quasar PKS 0528+134 in energy range 0.75 MeV to 30 carried out between April 1991 and September 1994 have been analyzed. During first two years was most significantly detected at energies above 3 MeV. last year there is only evidence for below indicating a spectral change. time-averaged spectrum well represented by power-law shape. Spectra collected from different observational periods reveal shapes: hard state during flaring reported EGRET, soft...