CV-Helios Network
Tables Contents

ZürichMcIntosh-classes

ZürichMcIntosh-table

Characteristics

CV Values table

 Classification
option Table I		 Classification
option Table II


Test your Classifications, see Explanations and CV-number


Sunspot Group Classification
1st Letter 2nd Letter 3rd Letter
Z-values: (Modified Zurich Sunspot Classification).   p-values:  c-values
    A - A small single unipolar sunspot.      x - no penumbra (group class is A or B)     x - undefined for unipolar groups (class A and H)
Representing either the formative      r - rudimentary penumbra partially      o - open. Few, if any, spots between leader and 
or final stage of evolution. surrounds the largest spot. follower. Interior spots of very small size. 
    B - Bipolar sunspot group with no          This penumbra is incomplete, granular  Class E and F groups of 'open' 
penumbra on any of the spots.   rather than filamentary, brighter than          category are equivalent to Zurich class G.
    C - A bipolar sunspot group. One  mature penumbra, and extends as little      i - intermediate. Numerous spots lie between the 
sunspot must have penumbra.  as 3 arcsecs from the spot umbra.  leading and following portions of the group, 
    D - A bipolar sunspot group with  Rudimentary penumbra may be either in a  but none of them possesses mature penumbra.
penumbra on both ends of the group.          stage of formation or dissolution.      c - compact. The area between the leading and 
Longitudinal extent does not      a - small, asymmetric. Penumbra of the  the following ends of the spot group is 
exceed 10 deg. largest spot is irregular in outline  populated with many strong spots, with at 
    E - A bipolar sunspot group with  and the multiple umbra within it are  least one interior spot possessing mature 
penumbra on both ends.  separated. The north-south diameter  penumbra. The extreme case of compact 
        Longitudinal extent exceeds 10 deg.  across the penumbra is less or equal than  distribution has the entire spot group 
but less than 15 deg.  2,5 degrees. enveloped in one continuous penumbral area.
    F - An elongated bipolar sunspot group      s - small, symmetric (like Zurich class J).   
with penumbra on both ends.  Largest spot has mature, dark, filamentary   
Longitudinal extent of penumbra  penumbra of circular or elliptical shape   
exceeds 15 deg.  with little irregularity to the border.   
    H - A unipolar sunspot group  The north-south diameter across the   
with penumbra.  penumbra is less or equal than 2.5 degrees.  
      k - large, assymetric. Same structure as type   
  'a', but north-south diameter of penumbra   
  is more than 2.5 degrees. Area, therefore,   
  must be larger or equal than 250 millionths   
  of the solar hemisphere.  
      h - large, symmetric (like Zurich class H).   
  Same structure as type 's', but north-south   
  diameter of penumbra is more than 2,5   
  degrees. Area, therefore, must be larger or   
  equal than 250 millionths of the solar hemisphere.