Mount Wilson Sunspot Magnetic
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Classification of the magnetic character of sunspots according to rules set forth by the Mount Wilson Observatory in California.
A unipolar sunspot group.
beta: A sunspot group having both positive and negative magnetic polarities (bipolar), with a simple and distinct division between the polarities.
gamma: A complex active region in which the positive and negative polarities are so irregularly distributed as to prevent classification as a bipolar group.
beta-gamma: A sunspot group that is bipolar but which is sufficiently complex that no single, continuous line can be drawn between spots of opposite polarities.
delta: A qualifier to magnetic classes(see below) indicating that umbrae separated by less than 2 degrees within one penumbra have opposite polarity.
beta-delta: A sunspot group of general beta magnetic classification but containing one (or more) delta spot(s).
beta-gamma-delta: A sunspot group of beta-gamma magnetic classification but containing one (or more) delta spot(s).
gamma-delta: A sunspot group of gamma magnetic classification but containing one (or more) delta spot(s).
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