Comparison Study of the Photographical and K-coronometrical Measurements of the July 10th 1972 Solar Eclipse Corona
Abstract
Summary. A comparison study of the K-coronometer measurements and the photographical photometry for the July 10, 1972 solar eclipse corona. We compare the K-coronometer measurements obtained at the Pic-du-Midi Observatory during the total eclipse of July 10, 1972, with the data obtained for the same (2' and 8') radial distances from the solar limb, by performing absolute photometry of a photograph taken at Anadyr (URSS), using a neutral radial attenuator. The absolute calibration of the negative was made by assuming the Saito Model (Saito, 1970) for the F and K-coronas at r >2 R0, and by taking the average brightness of the sky equal to: 13 10-10 [B0]. We find satisfactory agreement, within a margin of error of about 10 %, provided we assume, at the west side, either a temporary variation of coronal intensity at 2', or a slight decentring of about 15" of the K-coronometer scannmg. We assume that the degree of polarisation, p at 2', is constant and equal to 0.30. At 8', we obtain good agreement with p = 0.55; however, the structures projected on the south pole are less intense on the K-coronometer scanning, which indicates that they are not situated near the plane of the sky. Key words: sun - solar corona - photometry - eclipse - K-coronometer
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 1973
- Bibcode:
- 1973A&A....26..467B