solar observing

Active Observers (Data submitted within the last year)

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.

February 20, 2013

• The NASA SDO mission released a fascinating video showing "rain" from a magnetic loop falling back onto the surface of the Sun.  It's not rain, but hot plasma magnetically levitated off the Sun!

February 15, 2013

• Observer k-coefficients have been recalculated or newly-calculated for 60 observers, including 24 active observers who did not previously have them.  The