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Presently, many models of the coronal magnetic field rely on photosphericvector magnetograms but these data have been shown to be problematic as thesole boundary information for nonlinear force-free field (NLFFF)extrapolations. Magnetic fields in the corona manifest themselves inhigh-energy images (X-rays and EUV) in the shapes of coronal loops, providingan additional constraint that at present is not used due to the mathematicalcomplications of incorporating such input into numerical models. Projectioneffects and the limited number of usable loops further complicate the use ofcoronal information. We develop and test an algorithm to use images showingcoronal loops in the modeling of the solar coronal magnetic field. We first fitprojected field lines with field lines of constant-\als force-free fields toapproximate the three-dimensional distribution of currents in the corona alonga sparse set of trajectories. We then apply a Grad-Rubin-like iterativetechnique to obtain a volume-filling nonlinear force-free model of the magneticfield, modifying method presented in \citet{Wheatland2007}. We thoroughly testthe technique on known analytical and solar-like model magnetic fieldspreviously used for comparing different extrapolation techniques\citep{Schrijver2006, Schrijver2008} and compare the results with thoseobtained by presently available methods that rely only on the photosphericdata. We conclude that we have developed a functioning method of modeling thecoronal magnetic field by combining the line-of-sight component of photosphericmagnetic field with information from coronal images. Vector magnetograms overthe full or partial photospheric boundary of the numerical domain couldoptionally be used.

Guiding Nonlinear Force-Free Modeling Using Coronal Observations: First Results Using a Quasi Grad-Rubin Scheme