Hα Observations of 8 June, 2004 Venus Transit

The cosmic event of Venus transit across the solar disk occurred on 8 June, 2004. The previous such event was witnessed about 122 years ago on 6 December, 1882. We observed this rare transit in H_α 6563 Å line-center from Udaipur Solar Observatory (USO) using both the full-disk and small field-of-view solar telescopes. In the earlier historical transits, a "black-drop" effect was observed in white light images, during the contact phases. The transit of 8 June, 2004 provided a unique opportunity to observe this effect, for the first time, in H_α. We report that the "black-drop" effect is present in H_α also, as in the white light observations made by the ground-based Global Oscillation Network Group (GONG) instrument and the space-borne Transition Region and Coronal Explorer (TRACE) satellite. We did not observe any noticeable "aureole" (atmospheric glow) around Venus during the ingress or egress phases. We have compared the H_α images with the multi-wavelength data obtained from the TRACE satellite.