Gert Gislher Lichti

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Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gammaray energy. In September 2008, Fermi observed the exceptionally luminous GRB(More)
Soft-gamma-ray repeaters (SGRs) are galactic X-ray stars that emit numerous short-duration (about 0.1 s) bursts of hard X-rays during sporadic active periods. They are thought to be magnetars: strongly magnetized neutron stars with emissions powered by the dissipation of magnetic energy. Here we report the detection of a long (380 s) giant flare from SGR(More)
Aims. Gamma-ray line emission from radioactive decay of Fe provides constraints on nucleosynthesis in massive stars and supernovae. Methods. The spectrometer SPI on board INTEGRAL has accumulated nearly three years of data on gamma-ray emission from the Galactic plane. We have analyzed these data with suitable instrumental-background models and sky(More)
Context. If one wants to understand the physics of blazars, better simultaneous observations are important at all wavelengths, so it was fortunate that a ToO observation of the TeV-emitting blazar Mrk 421 with INTEGRAL could be triggered in June 2006 by an increase in the RXTE count rate to more than 30 mCrab. The source was then observed with all INTEGRAL(More)
We performed a spectroscopic study of the 1809 keV gamma-ray line from 26Al decay in the Galaxy using the SPI imaging spectrometer with its high-resolution Ge detector camera on the INTEGRAL observatory. We analyzed observations of the first two mission years, fitting spectra from all 7130 telescope pointings in narrow energy bins to models of instrumental(More)
One of the scientific goals of the main instrument of GLAST is the study of Gamma-Ray Bursts (GRBs) in the energy range from ∼ 20 MeV to ∼ 300 GeV. In order to extend the energy measurement towards lower energies a secondary instrument, the GLAST Burst Monitor (GBM), will measure GRBs from ∼ 10 keV to ∼ 25 MeV and will therefore allow the investigation of(More)
A giant flare from the Soft Gamma-ray Repeater SGR 1806–20 has been discovered with the INTEGRAL gamma-ray observatory on 2004 December 27 and detected by many other satellites. This tremendous outburst, the first one observed from this source, was a hundred times more powerful than the two giant flares previously observed from other Soft Gamma-ray(More)
The Compton Gamma-Ray Observatory (CGRO) experiments EGRET and COMPTEL observed the Virgo sky region continuously for 7 weeks between December 10, 1996 and January 28, 1997. The prominent quasar 3C 273 was found to be the brightest source in γ-rays and was significantly detected by EGRET and COMPTEL. The EGRET experiment observed a time-variable flux at(More)
We present an analysis of COMPTEL observations made between November 1991 and May 1994 of 2CG 135+01, a bright γ-ray source located near the Galactic plane. At energies above 1 MeV, an excess consistent with the position of 2CG 135+01 is detected in the sum of the observations, at flux levels which are a factor of 10 − 100 below those published in the past.(More)