sun

About the SID Database

The Sudden Ionospheric Disturbance (SID) Database lists all events identified in the AAVSO Solar Bulletin. These results are provided monthly by the worldwide network of SID observers in the AAVSO Solar Division. Individual results are correlated with other observers' reports and reduced to a list of events with high definiteness ratings.

The latest version of the Gyrator series of VLF receivers (first developed in the 1990s) is the Gyrator III, a revision of Arthur Stokes' Gyrator II by Guglielmo Di Filippo (observer A-93).

Circuit diagrams and wiring for the Gyrator III are available here in Microsoft Word and PDF formats: .doc, .pdf

Active Observers (Data submitted within the last year)

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.

VERY LOW FREQUENCY (VLF) RADIO STATIONS
                                     
           Station            Station     Frequency        Radiated
             Site               ID          (kHz)            Power
                                                             (kW)
  U.S.

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)

The Zurich Classification System of Sunspot Groups

Contributed by Tom Fleming (FLET)

"A" Type: One or more tiny spots that do not demonstrate bi-polarity or exhibit penumbra.

"B" Type: Two or more tiny spots that demonstrate bi-polarity but do not exhibit penumbra.

Contributed by Carl E. Feehrer (FEEC)

Revised August 2000

Addendum

ACCURACY AND CONSISTENCY IN THE PRODUCTION OF THE AMERICAN SUNSPOT NUMBER (Ra)

Contributed by Carl E.