by Darrel Emerson, AA7FV and G3SYS QST, published by ARRL. Vol
79, No. 2, February 1995, p.21. (Copyright on the original
article is held by the ARRL.) In July 1991 and in May 1994,
partial solar eclipses were visible from the QTH of AA7FV in
Tucson Arizona. For both events, a simple Yagi antenna was left
pointing in advance at the mid-point of the eclipse, and the
total noise output power from a ham radio receiver, tuned either
to 146 MHz or to 436 MHz, was recorded. During the July 1991
event, the sun was quite active. The trace below shows the
signal recorded at 146 MHz over a period of 6 hours. The
vertical dashed lines show the times of start, maximum
obscuration, and ending of the optical eclipse. The base noise
level gradually rises as the sun drifts into the antenna beam,
with strong solar bursts superposed. The solar noise drops
fairly abruptly about 1 hour after the onset of the eclipse, but
returns about 13 minutes before the end of the eclipse. This
shows that the region producing the radio emissi