Eclipses of the Sun

Abstract

Since the publication of Band IV, five total eclipses have been observed. The eclipse of May 9, 1929 was visible in northern Sumatra, the Malay States, Siam and the Philippines. Many expeditions were attracted to the eclipse track in spite of the great distances that must be travelled and the uncertainty of tropical weather. The Potsdam expedition of Freundlich, Grotrian, and von Klüber was located at Takengon in Sumatra with a well planned program, spectroscopic and photometric, together with an investigation of the relativity displacement. Near by was the Swarthmore party with the 63-foot tower telescope, with a pair of 15-foot Einstein cameras and with smaller instruments. Regarding the weather Miller writes1, “At the time of first contact the sun was invisible, but the blue circular patch still drifted slowly on. Sometimes during the partial phase one could tell by using field glasses that the sun was eclipsed. Ten minutes before second contact we took our places at the instruments, having decided to make all exposures regardless of the clouds. At that time one could not tell with the unaided eye that the sun was in partial eclipse. Five minutes before totality it was considerably brighter, and at totality the sun was in the center of the circular blue patch, which to the eye seemed perfectly clear. It remained clear during the entire period of totality; then the clear patch moved on, and half an hour after totality the sun was again obscured by clouds.”

The erratum of this chapter is available at http://dx.doi.org/10.1007/978-3-642-50955-1_36