Solar Physics, vol. 77, Apr. 1982, p. 69-75.
Bonet, J. A.; Ponz, J. D.; Vazquez, M.
The width distribution of the penumbral filaments is estimated using white light photographs obtained with a vacuum, Newtonian type telescope. Observations were made during the solar eclipse of June 1973 in order to allow simultaneous recording on each frame of the moon limb crossing on the photosphere, as well as the sunspot and penumbra of interest. The relevant parameter, filament width, is defined as the sum of the segments obtained by drawing a vertical line through a relative maximum, the tangents to the profile in adjacent minima, and horizontal lines through the mean points of the segments. The width distribution results from joint analysis of the selected areas. The mean value of the width of penumbral filaments was estimated to be 0.37 arcsec.