Polarization of Venus I Disk Observations
Abstract
New observations are presented for the linear polarization of suniight scattered by the Venus atmosphere, with wavelength dependence from 0.3 to 1.0 . Data are given for the integrated disk as well as for the equatorial regien. Measurements were made in France and in the United States with independent techniques; their agreement is generally better than + 0.3% polarization. Observations were made in the phase angle range of - 1760.5. The large ultraviolet polarization at 180 phase angle remains from year to year, but varies in amplitude, as does the broad ultraviolet polarization peak centered at V 770 Any diurnal variations are lost in the observational scatter, but a pronounced secular effect was found: the ultraviolet polarization was low between the middie of 1964 and the end of 1965, compared to both the 5 years preceding this period and the 4 years following. The negative branch at small phase angles is here confirmed, and found to exist throughout the range 5000 A - 10000 A. The positive polarization at 1600 phase angle is present between 3400 A and 7000 A, but is absent farther in the infrared. At 10000 A the polarization of Venus is negative at all phase angles. A synthesis is made of all available disk polarimetry, giving the mean variation with wavelength and phase angle.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 1970
- Bibcode:
- 1970A&A.....8..251D