1. SPD May 25, 2005 RHESSI soft X-ray imaging spectroscopy H. Hudson & A. Caspi (SSL/UCB) And B. Dennis & K. Phillips (NASA/GSFC

2. SPD May 25, 2005 Comments RHESSI data are the first systematic use of a non-dispersive spectrometer for soft X-rays Data have high precision but low resolution (~6-8 for K-shell Fe transitions) Two features independently observable (Phillips et al. 2004; see Caspi presentation)

3. SPD May 25, 2005 Fe feature for different ionization levels Fe I Fe XXV Fe XVI

4. SPD May 25, 2005 Significance Fe lines offer a different view of hot flare plasmas DEM, flourescence, non-equilibrium ionization states

5. SPD May 25, 2005 Fe feature 3-18 keV

6. SPD May 25, 2005 Search objectives and database Flourescent emission from hard X-ray ionizations may produce Fe K-line emission from lower atmosphere Identify 16 events with early intense hard X-ray bursts, favoring K-line (6.4 keV) over FeXXIV-FeXXV complex (6.7 keV)

7. SPD May 25, 2005

9. HXR Centroid

10. SPD May 25, 2005 Conclusions In our sample there was no evidence for K- line contributions

11. SPD May 25, 2005 END