Multispacecraft observations of the hard X-ray emission from the giant solar flare on 2003 November 4

Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, 94720-7450, USA e-mail: sharadkane12@msn.com

Received: 19 August 2004
Accepted: 20 December 2004

Abstract

The hard X-ray emission from the “giant” solar flare on 4 November 2003 (~1947 UT) was observed by the hard X-ray/gamma ray spectrometer on the Ulysses spacecraft located at ~114 degrees west of the Sun-Earth line at a distance of 5.28 AU from the Sun. A “small” hard X-ray burst during the early rise of the giant flare and a part of the decay of the hard X-ray emission associated with the giant flare were also observed by the hard X-ray imager on the RHESSI satellite located near the Earth. The maximum of the hard X-ray emission during the giant flare could not be observed by the RHESSI instrument because of satellite night. The flare view angles for Ulysses and RHESSI were ~31° West and 83° East respectively. The H-α flare (importance 3B) was located at S19 W83 in the active region NOAA 10486. GOES observations of the associated soft X-ray emission 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. OVSA radio observations show that the flare produced intense microwave emission, the peak flux at 15.4 GHz being ~60 000 sfu at ~1945 UT. Intense type II, III and IV radio bursts have also been reported at metric and decimetric wavelengths. RHESSI has provided 10–100 keV X-ray images and spectra for 1930–1936 UT (the early rise of the flare) and 10–30 keV images and spectra for 2016–2114 UT (a part of the late decay of the flare). Ulysses observed an increase in 25–150 keV X-rays from 1933 UT to 2015 UT with the maximum at ~1944 UT, almost simultaneously with the maximum in 15.4 GHz radio 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 hard X-ray spectrum of ~ for >20 keV photons leads to an energy dissipation rate of ∼ at the time of the hard X-ray maximum. The total energy in >20 keV electrons released during the flare is estimated to be ~.