USING STRONG SOLAR CORONAL EMISSION-LINES AS CORONAL FLUX PROXIES

We investigate the possibility that strong EUV lines observed with the Goddard Solar EUV Rocket Telescope and Spectrograph (SERTS) provide g ood proxies for estimating the total coronal flux over shorter wavelen gth ranges. We use coordinated SERTS and Yohkoh observations to obtain both polynomial and power-law fits relating the broad-band soft X-ray fluxes to the intensities of Fe XVI 335 Angstrom and 361 Angstrom, Fe XV 284 Angstrom and 417 Angstrom, and Mg IX 368 Angstrom measured wit h SERTS. We found that the power-law fits best cover the full range of solar conditions from quiet Sun through active region, though not sur prisingly the 'cooler' Mg IX 368 Angstrom line proves to be a poor pro xy. The quadratic polynomial fits yield fair agreement over a large ra nge for all but the Mg ur line. However, the linear fits fail conspicu ously when extrapolated into the quiet-Sun regime. The implications of this work for the He II 304 Angstrom line formation problem are also briefly considered.