VIEWING THE 1998 SOLAR ECLIPSE THROUGH THE CLOUDS

JAMES A. PETRAIT

Pictured above is the sun over St. Croix on a bright and clear day. The photo was taken with an electronic camera with a mylar filter and then it was colorized and stetched in a computer. The disk of the sun was not visible on Feb.26, 1998 during the almost total eclipse on St. Croix. A heavy layer of clouds obsured the view from the location of St. Joseph High School. But we were able to view the almost exact time of the maximum of the eclipse by means of a calibrated photocell and a digital current meter.

Expecting the worse, I ordered a calibrated photo cell from the Edmund Scientific Company. The photocell has a linear output and the intensity of the light is directly related to the current on a digital meter. I placed the photocell in a glass jar and placed it on the roof of my classroom. While the moon was coming in front of the sun, the current on the meter began to go down. I had 2 students take turns writing down the current every few minutes. The change in the amount of light level caused by the changing of the cloud thickness did not seem to have caused any great variations in the results which clearly showed the time of the maximum eclipse of over 90%.

Pictured below is the graph of the 87 points of data. The starting time was 12:43 PM AST and the ending time was 2:38 PM AST. Current readings started at 52.0 ma and ended with 30.5 ma. The lowest current reading (maximum eclipse) was 0.53 ma and it happened at 2:27 PM AST.

In anticipation of the eclipse, I made solar viewing (mylar) cards available to the entire school but because of the overcast sky, my students and I were the only ones able to "see" the eclipse by means of the graphical representation of the data.

Below is one of my students testing out a solar viewing card on a sunny day on St. Croix.

Below is the unstretched photo of the sun in the heading.

A special thanks to Melissa Thurland and Chalma Moorhead for recording the observations and to Melissa Thurland making the first graph of the data.

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Send e-mail to James A. Petrait: jpetrait@earthling.net

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