On-line Conference - How to count sunspots
It takes months to learn how to count sunspots.
I would like to invite best sun, sunspots pro observers from observatories world-wide
to train us in manual count of sunspots.
Images of the solar disc come from NASA, NOAA, ESA, internet space weather services
and I expect pro sun, sunspot observers to count sunspots for a series of images of the solar disc
and have calculations supported by attached images from the internet.
Let me know your opinion.
What are sunspots?
REDUCTION OF SUNSPOT-NUMBER
A. H. Shapley
National Bureau of Standards
The Ri human factor: human vision
September 2011 Sunspot Index Workshop, Sac Peak
What is the smallest possible sunspot ?
• Various definitions:
– Semantic problem “pore” vs “sunspot”:
• Pore = small spot without penumbra
• Pore = random intergranular blemishes that are not real sunspots
• Overall agreement: lowest spot size near 2000 km (3 arcsec)
The range of
observed numbers on a single day can be remarkably broad.
For instance, on April 20, 1948, the 30 observers reporting
14 A. H. SHAPLEY
through the American Association of Variable Star Observers
Solar Division gave numbers (10(7 +f) from 41 to 318; ad-
justed to the Wolf scale the range was 91 to 322.