1. Joint session WG4/5 Points for discussion: - Soft-hard-soft spectral behaviour – again - Non-thermal pre-impulsive coronal sources - Very dense coronal loops (~ 10 11 cm -3 ) and other dense structures - Coronal sources that decrease in altitude (sometimes as footpoints approach), then increase - tiny inferred size of flare footpoints  high beam flux and implications

2. 30-50 keV intensity 30-50 keV / 20-30 keV intensity ratio 50-70 keV / 30-50 keV intensity ratio Correlation between impulsive phase intensity and spectral hardness - ubiquitous Spectral soft – hard - soft

3. GOES 1-8 A DERIVATIVE Non-thermal preflare coronal sources

4. RHESSI Preflare Maps 3-12 keV (color): 12-25 keV (contours) 01:07:00-01:08:30 01:08:00-01:10:30 01:11:00-01:12:30 Coronal source

5. RHESSI SPECTRA 5-50 keV Thermal+broken powerlaw Preflare period: 01:02:00-01:11:00 Broken powerlaw extends down to 5 keV Thermal component never dominates EM and T are poorly determined Chisquare ~ 1 if EM=0 White = photons, Green = thermal model, Red = broken powerlaw, Purple = background (NB similar source in July 23 rd 2002 event)

6. Dense coronal sources Substantial high energy emission in corona: thermal and radio observations allow estimate of density – 10 11 cm -3 20-30 keV30-50 keV50-100 keV 20 July 2002, pixon image reconstruction

7. Descending loop top sources Time evolution: blue  white Footpoints: 70-100 keV Loop top: 20-25 keV

8. H  footpoint separation HXR source ‘height’ Descending loop top sources – with decreasing footpoint separation

9. Flare footpoints – white light observations WL coincides with HXR source locations – sizes at resolution of TRACE (few px = few 1000 km  area ~ 10 17 cm 2 )

10. M2.2 flare Predicted ‘evaporation’ velocity as function of beam flux Using A= 10 18 cm 2 Using A= 10 17 cm 2