AAS 204th Meeting, June 2004
Session 47 When the Sun Went Wild
Topical Session, Tuesday, June 1, 2004, 2:30-4:00pm, 4:15-6:00pm, 702/704/706

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[47.06] Stereoscopic Observations of the Hard X-ray Source in the Giant Solar Flare on 4 November 2003

S. R. Kane, J. M. McTiernan, K. Hurley (Space Sciences Laboratory, University of California, Berkeley)

The hard X-ray source in the “giant” solar flare on 4 November 2003 (~1947 UT) was observed by instruments aboard two spacecraft: RHESSI, located near the Earth, and Ulysses, located at ~ 114 degrees west of the Sun-Earth line at a distance of 5.23 AU from the Sun. While Ulysses observed hard X-rays during most of the flare, RHESSI observations covered only the early rise and part of the decay of the flare. The maximum of the flare could not be observed by RHESSI because of satellite night. The H-alpha flare (importance 3B) was located at S19 W83 in the active region NOAA 10486. The associated soft X-ray emission, observed by GOES, saturated during the period 1943-1958 UT. It has been estimated that the soft X-ray maximum occurred at ~1947 UT with peak flux equivalent to NOAA class X28. The flare produced intense microwave radio emission. At 15.4 GHz a peak flux of 60000 sfu was observed at ~1945 UT. Intense type II, III and IV radio bursts have also been reported at metric and decimetric wavelengths. RHESSI has provided 10-50 keV X-ray images and spectra during 1930-1938 UT (the early rise of the flare) and 10-30 keV images and spectra during 2016-2114 UT (a part of the decay of the flare). Ulysses observed an increase in 25-150 keV X-rays from 1933 UT to 2015 UT. The peak counting rate, corrected for live time and normalized to Earth’s distance from the Sun, was ~1.0E+07 counts per sec. It occurred at ~1944 UT in close time coincidence with the maximum in 15.4 GHz microwave emission and ~3 min before the maximum in the soft X-ray emission. This indicates that the X-ray emission observed by Ulysses was mostly non-thermal. An assumed differential hard X-ray spectrum with power law exponent of -3.5 for >20 keV photons, leads to an energy dissipation rate of ~5.0E+31 ergs per sec at the time of the hard X-ray maximum. The total energy in >20 keV electrons released during the flare is estimated to be ~1.0E+34 ergs. Implications of such a large magnitude of energy release for models of solar flares will be briefly discussed.

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