Wednesday, 3 December 2008

Lascar display IV

Now the sun elevation at Lascar is 2-3 degrees. The image is four frame stack. 20° upper plate arc is well visible. New feature, "Moilanen arc", has appeared. We observed it visually, it was V-shaped, not like the light mass seen in this photo. Photographing this arc was difficult, because it appeared and disappeared in seconds intervals. Measurements from two slides placed the arc at 10.5° from the sun, which is less than for Moilanen arc. But of course there is uncertainty in that value.

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