18 June 2007: Venus occultation

Jean-Luc Dighaye, Manfred Rudolf

On 18 June 2007, a daytime occultation of Venus by the Moon could be observed from Munich. Weather was partly cloudy at POR, especially during ingress and egress,and seeing was very poor.

Venus and the Moon were spotted using the finder of the C11, then the angle magnifier of the modified 5D at the prime focus of the apochromat. Clouds became thicker around ingress, which could not be properly observed visually. Pictures taken without filter at ISO 100 and 1/2500s exposure do reveal, though, pale images of Venus, presented here with extreme contrast enhancement bringing substantial noise.

The Moon could be seen shortly before egress, but thick clouds formed then. Just after egress time, a clearing came abruptly, allowing for some hazy images first, then much clearer views of "boiling" Venus (due to turbulence) having emerged from the grey-brown lunar crescent.

The weather conditions at SOT were substantially the same, ingress was completely clouded out, and also the begin of egress. A video sequence of the egress has been recorded, here two frames of this video:

After egress, some clearings allowed a view of the Moon and Venus which could easily be spotted with the naked eye (Canon D20a, lens 500mm 5.6):