Sudden Ionospheric Disturbances (SIDs)

The AAVSO SID Program consists of solar observers who monitor very low frequency (VLF) radio stations for sudden enhancements of their signals. Earth's ionosphere reacts to the intense X-ray and ultraviolet radiation released during a solar flare. The ionospheric disturbance enhances VLF radio propagation. By monitoring the signal strength of a distant VLF transmitter, sudden ionospheric disturbances (SIDs) are recorded and indicate a recent solar flare event.

SID Monitoring Group FAQ

When the ultraviolet rays from the Sun hit the Earths atmosphere the energy they possess work to knock electrons off of the atoms and molecules that the atmosphere is made up of. These free electrons make up a region of the atmosphere known as the Ionosphere. The region is strongest on the daytime side of the earth since it is dependant on the energy from the solar ultra violet rays.

SID Data Report Format

The AAVSO SID section provides a number of options for data logging, data reduction and report generation. You may or may not use one or all of these methods. How you monitor SIDs and how you generate a report is up to you and left open to personal preference. The only constraint imposed by the SID Program as a requirement for submitting data is the format of that data. Two requirements must be met. One is the internal format and the second is the file name convention of the formatted report.

SID Software

Two software packages are typically used by SID observers. One is the data taking or logging software, and the other is the data reduction software. The AAVSO provides some options but you may wish to create your own custom software. If you submit your data to the AAVSO SID program the report format must match a pre-defined format, therefore any custom software must generate an appropriate data file.

The section below lists the software made available by the AAVSO SID program. These are available by writing the SID Analyst, and will include instructions for use.

SID Equipment

Note: Some of the following articles written by Cap Hossfield include references to Radio Shack part numbers. These were commonly available at the time of his writing but may no longer be so today. Cap also includes offers to sell some of the circuits he describes to interested parties and to supply tuning services to those that do not have the proper equipment to do so. Sadly Cap is no longer with us and therefore these offers are no longer valid.