SOLAR CORONAL TEMPERATURE DIAGNOSTICS USING EMISSION-LINES FROM MULTIPLE STAGES OF IONIZATION OF IRON

We obtained spatially resolved extreme-ultraviolet (EUV) spectra of AR 6615 on 1991 May 7 with NASA/Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph (SERTS). Included are emission lines from four different stages of ionization of iron: Fe+15 lambda335 angstrom, Fe+14 lambda327 angstrom, Fe+13 lambda334 angstrom, and Fe+12 lambda348 angstrom. Using intensity ratios from among these lines, we have calculated the active region coronal temperature along the SERTS slit. Temperatures derived from line ratios which incorporate adjacent stages of ionization are most sensitive to measurement uncertainties and yield the largest scatter. Temperatures derived from line ratios which incorporate nonadjacent stages of ionization are less sensitive to measurement uncertainities and yield little scatter. The active region temperature derived from these latter ratios has an average value of 2.54 x 10(6) K, with a standard deviation approximately 0.12 x 10(6) K, and shows no significant variation with position along the slit.