Magnetic field of quiescent prominences of August 11, 1999

Polarimetric researches of H-alpha prominences are presented. Observations were made by a full-limb portable coronagraph-polarimeter during the August 11, 1999, total solar eclipse. Distributions of linear polarization degree in the picture plane for active and quiescent prominences are obtained with an accuracy of 1 percent. Three quiescent prominences are chosen for further analysis aimed at magnetic field strength determination. Main depolarization factors such as the Hanle effect and optical depth are discussed. Magnetic field strength deduced from comparative analysis of measured polarization degree and a theoretically calculated one for a similar type of prominences is estimated to equal 0.5-11.0 G.