Astronomy and Astrophysics (ISSN 0004-6361), vol. 233, no. 2, July 1990, p. L17-L20.
Donati, J.-F.; Semel, M.; del Toro Iniestia, J. C.
The magnetic field of the Ap star Epsilon UMa was measured using the Zeeman-Doppler Imaging method. Ultrahigh S/N polarized profiles of the 4923 A magnetically sensitive Fe II line were recorded. Unambiguous Zeeman signatures were found at phases here S/N was greater than or equal to 1750.