The spectral index,, steepens with time, changing from about -0.7 to -0.9 (see. At any given epoch, the radio spectrum can be modelled by a power law, S. Subsequently, around day 14, the light curve flattens to - 1. The radio source from SGR 1900 + 14 following the 27 August 1998 giant flare showed a similar rapid decay at 8 GHz. xminset, boolean, Whether user-set minimum value of the abscissa should be used (otherwise. After the first break (nine days postburst) the light curve steepens to - 4 - 3. Each atomic type except boolean has its array counterpart. These breaks are clearly seen in our highest signal-to-noise ratio data. At each band we model the flux with a power law, S ( t ) t, but allow for changes in the temporal indices ('breaks') at two epochs. The radio source decays in all frequency bands, but its behaviour is complex (Fig. In Table 1 we report the results of a subsequent monitoring programme undertaken with the VLA, the Giant Metre-wave Radio Telescope (GMRT), the Australia Telescope Compact Array (ATCA), the Nobeyama Millimeter Array (NMA) and the Institut de Radioastronomie Millimétrique (IRAM) 30-m telescope. On 3 January 2005 we observed SGR 1806-20 with the Very Large Array (VLA) and identified and promptly reported a new radio source at right ascension J 2000 = 18 h 08 min 39.34 s and declination J 2000 = -20 24' 39.7" (with an uncertainty of 0.1" in each coordinate) coincident with the quiescent X-ray counterpart. Instead, we suggest that the rapidly decaying radio emission arises from the debris ejected during the explosion. The energetics and the rapid decay of the radio source are not compatible with the afterglow model that is usually invoked for -ray bursts. If correct, our distance estimate lowers the total energy of the explosion and relaxes the demands on theoretical models. Analysis of the spectrum yields the first direct distance measurement of SGR 1806 - 20: the source is located at a distance greater than 6.4 kpc and we argue that it is nearer than 9.8 kpc. We began a monitoring programme from 0.2 to 250 GHz and obtained a high-resolution 21-cm radio spectrum that traces the intervening interstellar neutral hydrogen clouds. Here we report the detection of a fading radio counterpart to this event. On 27 December 2004, a giant flare with a fluence exceeding 0.3 erg cm -2 was detected from SGR 1806-20. It was established over a decade ago that the remarkable high-energy transients known as soft -ray repeaters (SGRs) are located in our Galaxy and originate from neutron stars with intense ( 10 15 G) magnetic fields-so-called 'magnetars'. Phinney Atsushi Miyazaki Masato Tsuboi Sachiko Okumura N.
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