Study of the June 30, 1973 trans-polar coronal hole

Radially and tangentially polarized pictures of the solar corona obtained near 4500 A during the 30 June, 1973 solar total eclipse have been used to derive a model of a trans-polar coronal hole. The hole is identified by using OSO-7 EUV spectroheliograms. The line of sight coincides with the privileged plan of the hole over the N-polar region. A new method of absolute calibration is used. The Saito (1970) method is applied to determine the electron densities. Extrapolated values of densities down to the surface are lower than have ever been observed although derived hydrostatic temperatures are certainly not: Nsub(e) = 1.8 x 107 cm -3 and T = 2 x 106 K. The morphological peculiarities of polar regions are considered. (Auth.)