VENUS TAIL RAY OBSERVATION NEAR-EARTH

In June, 1996, Venus passed through a very close inferior conjunction with the Sun, At that time the CTOF detector of the CELIAS mass spectr ometer experiment on the SOHO spacecraft near Earth's L1 Lagrangian po int was measuring heavy ions in the solar wind similar to 4.5x10(7) km downstream of Venus. Close to the time predicted by simple geometric arguments for passage of SOHO through the Venus wake, CTOF made three encounters with unusual fluxes of O+ and C+ ions. Their energy distrib utions resembled those of tail rays originating in the Venus ionospher e or ionopause region rather than of ions produced in the corona of ne utral atoms that surrounds the planet. The C+ abundance was approximat e to 10% of O+. The observed O+ speed was very close to the simultaneo us solar wind speed and the O+ temperature was a cool 5600 K/amu. The flux densities for the three events were (2.4-4.4)x10(3) cm(-2)s(-1).