Solar Observing Program

For more information on the Solar Committee contact Chairperson Paul Mortfield (Paul@IndustrialStars.com).

Our Active Sun Click image to enlarge.

Photo taken on March 27, 2001 at 14:40 UT by AAVSO observer A. Gonzalo Vargas, Cochamamba, Bolivia. Active region 9393 appears below the center in this orientation.

The main activity of the AAVSO Solar Committee is the monitoring of sunspots from which the American Relative Sunspot Numbers (R_A) are computed. This program was started in 1944 when the Solar Committee was first formed. The AAVSO American Relative Sunspot Program produces an independent sunspot index.

For many years the program based its results on the reports of a limited number of skilled observers in the United States. Today however, it has grown in size and sophistication. The program now benefits from the participation of over 100 amateur and professional astronomer collaborators on six continents, who provide continuous coverage of the Sun.

Those who participate in the American Relative Sunspot Program use relatively small instruments for sunspot observations. The sun is observed each clear day, and counts are made of the number of sunspot groups and the total number of spots. These observations are reported on a standard form which is sent to the Chairman of the AAVSO Solar Committee at the end of each month.

The statistical methods of analysis used for data reduction were devised by J. Virginia Lincoln and Alan Shapley of the National Oceanic and Atmospheric Administration (NOAA). Their methods have been computerized, allowing for reduction of data on a timely basis. The data reduction technique is described in Taylor, 1985, Journ. AAVSO 14, 28. The processing has been modified to account for a longterm inflation of sunspot numbers due to the repeated computation of observer-dependant coefficients first identified by Schaefer, 1997, Journ. AAVSO 26, 40.

Information from all observers is generally received by the 10th of each month. After an initial review by the committee Chairman, reports are processed and archived. The final values of the American Relative Sunspot Numbers are computed by the 15th of each month and distributed to the National Oceanic and Atmospheric Administration (NOAA), subscribing universities, scientific organizations, and interested individuals via e-mail and the monthly newsletter, the AAVSO Solar Bulletin.

SIDs - Sudden Ionospheric Disturbances

The AAVSO Solar Committee also includes the work of a smaller group of electronic observers who monitor very low frequency radio stations for sudden enhancements of their signals (Sudden Ionospheric Disturbances), and thus detect solar flares indirectly. Although this work was initiated in 1956 as part of the International Geophysical Year, only a few monitoring stations are presently located outside the United States, and so additional European and Asian locations would be particularly welcome. These flare patrol results are also sent to NOAA each month.

• SID Program - The Sudden Ionospheric Disturbances page includes general SID information and links to SID event reports, how to make SID hardware, and the SID Database

Sunspot indices and flare data are regularly published in Solar-Geophysical Data and other publications.

More Information

• The Solar Bulletin
• Solar Photo Gallery
• In the News

Sunspots

• American Relative Sunspot Numbers
• Atmospheric Seeing Conditions
• The Zurich Classification System of Sunspot Groups
• Dances With Wolf's: A Short History of Sunspot Indices
• Addendum: Accuracy and Consistency in the Production of the American Sunspot Number (Ra)
• Guidelines for New Solar Observers
• Useful Links for New Solar Observers
• Software To Help With Solar Observations