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Sudden Ionispheric 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.

Solar Section

Section Leaders:

Rodney Howe      Contact
Kristine Larsen
Kim Hay

Interested in joining this section? Click here for instructions.


Introducing the SID Data Grabber

Thanks to a great volunteer effort by George Silvis, Sudden Ionospheric Disturbance (SID) observers can now use the SID Data Grabber help prepare an AAVSO SID report file from their Stanford/SARA superSID monitor log files. Please visit the SID Data Grabber page to read more and download this handy application.

SID Data Grabber

The SID Data Grabber is an application to help prepare an AAVSO SID report file from your Stanford/SARA superSID monitor log files. It offers a zoomable graphical view of the log data where you can click the graph to grab the times then puts them into the AAVSO format report file, ready for submission at the end of the month.

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.

VLF Station List

           Station            Station     Frequency        Radiated
             Site               ID          (kHz)            Power
  U.S. Navy                     
       Cutler, ME                NAA          24.0            1000
       Jim Creek, WA             NLK          24.8             250
       Lualualei, HI             NPM          21.4             566
       LaMoure, ND               NML          25.2             500

Solar Program, Reducing Data and Email Format

Solar Program, Reducing Data and Email Format

Reducing Data Gathered by VLF Monitoring Systems

(Extracted from SID Technical Bulletin Vol. 3, Number 4, Oct. 1992)

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.


AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484