2005/02/25 by E. P. Mazets, E. Mazets, T. L. Cline +18
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #Gamma-ray bursts and supernovae #Pulsars and Gravitational Waves Research #Solar and Space Plasma Dynamics #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0502541
5 pages, 7 figures
arxiv created 2005/02/25 · openalex publication_date 2005/02/25 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The giant outburst from SGR 1806-20 was observed on 2004 December 27 by many spacecraft. This extremely rare event exhibits a striking similarity to the two giant outbursts thus far observed, on 1979 March 5 from SGR 0526-66 and 1998 August 27 from SGR 1900+14. All the three outbursts start with a short giant radiation pulse followed by a weaker tail. The tail pulsates with the period of neutron star rotation of ∼5--8 s, to decay finally in a few minutes. The enormous intensity of the initial pulse proved to be far above the saturation level of the gamma-ray detectors, with the result that the most valuable data on the time structure and energy spectrum of the pulse is lost. At the time of the December 27 outburst, a Russian spacecraft Coronas-F with a γ-ray spectrometer aboard was occulted by the Earth and could not see the outburst. It succeeded, however, in observing a weak reflected signal due to the γ-rays Compton scattered by the Moon. This has been the first observation of a cosmic gamma-ray flare reflected from a celestial body. Here we report, that the detection of a weakened back-scattered initial pulse combined with direct observations by the Konus γ-ray spectrometer on the Wind spacecraft permitted us to reliably reconstruct the intensity, time history, and energy spectra of the outburst.