Carrington had spotted brightening's of small areas within a sunspot group.

Zirin, H. and Werner (Kieffer), S., Detailed analysis of flares, magnetic fields and activity in the sunspot group of September 13-26, 1963, Solar Physics, 1, 66-100, 1967.

With this baseline of almost 200 meters, the authors determined that the solar radiation during the burst phase was much smaller than the solar disk and arose from a region associated with a large sunspot group.

She could see two great sunspot groups and a hint, she thought, a shadow, of some of the material in the ring plane.

He pointed out that this synchronised "with the entire passage across the visible disc" of sunspot group 885 (Greenwich numbering).

Solar flares were first observed on the Sun by Richard Christopher Carrington and independently by Richard Hodgson in 1859 as localized visible brightenings of small areas within a sunspot group.

Peaked at 01:56 UT on February 15, 2011 sunspot group 1158 produced an X2.2-class solar flare.

Variations about the average up to 0.3% are caused by large sunspot groups and of +0.05% by large faculae and bright network on a week to 10 day timescale.

GONG can detect sunspot groups on the far side of the Sun.

Their instruments detected weak radio emissions and bursts of soft X-rays from the sunspot group.