title: Neutral points of skylight polarization observed during the total eclipse on 11 August 1999.
abstract: We report here on the observation of unpolarized (neutral) points in the sky during the total solar eclipse on 11 August 1999. Near the zenith a neutral point was observed at 450 nm at two different points of time during totality. Around this celestial point the distribution of the angle of polarization was heterogeneous: The electric field vectors on the one side were approximately perpendicular to those on the other side. At another moment of totality, near the zenith a local minimum of the degree of linear polarization occurred at 550 nm. Near the antisolar meridian, at a low elevation another two neutral points occurred at 450 nm at a certain moment during totality. Approximately at the position of these neutral points, at another moment of totality a local minimum of the degree of polarization occurred at 550 nm, whereas at 450 nm a neutral point was observed, around which the angle-of-polarization pattern was homogeneous: The electric field vectors were approximately horizontal on both sides of the neutral point.
authors.affiliation: Department of Biological Physics, Eötvös University, H-1117 Budapest, Pázmány sétény 1., Hungary. gh@arago.elte.hu
authors.forename: Gábor
authors.initials: G
authors.lastname: Horváth
authors.forename: István
authors.initials: I
authors.lastname: Pomozi
authors.forename: József
authors.initials: J
authors.lastname: Gál