The center-to-limb behavior of solar active regions at ultraviolet wavelengths P. C. Crane, L. E. Floyd, J. W. Cook, L. C. Herring, E. H. Avrett and D. K. Prinz A&A, 419 2 (2004) 735-746 Published online: 03 May 2004 DOI: 10.1051/0004-6361:20040012