A MOVING PICTURE OF THE RECENT PARTIAL ECLIPSE OF THE SUN

Abstract

The recent eclipse of the Sun, which occurred February 3, 1935, was undoubtedly photographed in many parts of the country. We thought it to be worth while to make a permanent record of the phenomenon in the form of a moving picture. Our observatory is located on the university campus in the midst of some rather tall buildings, which gave us great concern, for the possibility of being able to photograph the first part of the eclipse seemed to be uncertain because of the low position of the Sun in the sky. We finally calculated that the Sun could be photographed for two minutes before the eclipse started. An Eastman Cine moving picture camera, with a lens of 12.5 inches focal length and a green filter in front of the camera, was employed. We adjusted the shutter of the camera to one-fourth of its normal opening and stopped the lens down to F.45. This arrangement was bolted to the tube of a four-inch equatorial telescope. Since the eclipse was to last for over two hours and since we had only 100 feet of film at our disposal, we decided to make the exposures at the rate of about one every two seconds. In fact the metronome was set to give 54 clicks every minute, which permitted us to make 27 exposures per minute. The arrangement of the camera was such that all exposures had to be made by pushing a button, which proved to be rather tiresome. Two observers were assigned, one to make the exposures and the other to observe the Sun's image at the focus of the telescope. The latter precaution seemed to be necessary, because of the unreliable performance of the clockwork on former occasions. At Lincoln, Nebraska, the eclipse, which was 58 per cent total, lasted from 8:55 a.m. to 11 :07 a.m. The points of first and last contact were determined visually and later checked by measurements on the film. The agreement between the two results was good but proved to be disappointing to us because we had hoped to increase the accuracy of this determination by measuring the film. It seems, therefore, that one can observe the times