Evidence of internal rotation and a helical magnetic field in the jet of the quasar NRAO 150 Sol N. Molina, Iván Agudo, José L. Gómez, Thomas P. Krichbaum, Iván Martí-Vidal and Alan L. Roy A&A, 566 (2014) A26 Published online: 03 June 2014 DOI: 10.1051/0004-6361/201423479