Article

23 July 2004

The SIDs program needs observers

This plot shows the amplitude of a VLF signal from a distant transmitter on a day with little solar activity. Image from the home page of the SIDs program of the American Association of variable Star Observers. The URL is given at the end of the accompanying news story. Click image to enlarge.

SIDs are Sudden Ionospheric Disturbances caused by solar flares.

The American Association of Variable Star Observers (AAVSO) conducts a program in which serious amateur observers monitor SIDs.

Observers use simple, reliable, home built very low frequency (VLF) radio receivers to monitor distant transmitters that transmit at VLF wavelengths. A SID will cause changes in the amplitude of the received signal, thus indicating the effect of a solar flare on the ionosphere.

The AAVSO SIDs web page links to a data page and various resources. Included are various SIDs receivers. One is simply a loop antenna connected to an operational amplifier and a chart recorder or data logger.

SIDs observations are a relatively new AAVSO program, and more observers are needed, especially from regions other than North America.

For additional information, visit the SIDs home page at www.aavso.org/observing/programs/solar/sid.shtml.

Forrest M. Mims III