Talk:Sunspot number

Seems wrong

The article says that "the idea of computing sunspot numbers was originated by Rudolf Wolf in 1849", and then goes on to say that "this number" has been collected for 300 years. Presumably Wolf must have back calculated the previous century. How was this done? Also the series seems to start in 1749, so it still doesn't span 300 years. Perturbationist (talk) 01:36, 29 June 2008 (UTC)[reply]

Good points. How about we get an image showing the Maunder Minimum? --Uncle Ed (talk) 18:31, 8 June 2011 (UTC)[reply]

How is k computed?

This article says:

k is a factor that varies with location and instrumentation (also known as the observatory factor).

This is an immense gap in the article. Does one find k by throwing dice? Does one use local property-tax rates? Does one poll the local population on their opinions of what k should be in their community? This looks like someone put there by a politician to impress gullible people. Michael Hardy (talk) 15:09, 5 April 2010 (UTC)[reply]

The personal reduction coefficient K

"A personal reduction coefficient K is calculated for each station. It has values typically in the range 0.4 and 1.7 and leads to a normalized sunspot number K(10G+S). In other words, the K factor rescales the raw sunspot counts of each observer to the ones of Rudolph Wolf, the astronomer who introduced the above Wolf formula, thus simulating the same eyes, same telescope and same conditions. During the procedure for calculating the Provisional ISN, the K factor of every station is computed for every observation that passes the elimination procedure. Once a year, a personal K factor for every station and for every month of the previous year is calculated. A yearly mean K value per station is also computed." --source

If all sunspots were the same size and round, counting them would be a more precise art. But they are neither. There seems to be no limit to how small they can get, and the more powerful the telescope the more of them one can see. And some sunspots can be quite amorphous, making it hard to tell whether you're looking at one, two, or more sunspots in a given formation. Hence the wide variation between stations, and the need to normalize in order to contribute a meaningful count to the global record. --Vaughan Pratt (talk) 00:08, 19 September 2011 (UTC)[reply]

10.4883 years/cycle

Why is the maximum number of 10.4883 years/cycle important, calculated by use of a FFT function? For what is this number useful? In the last 300 years there was an average of 11.04 or 10.66 years/cycle, depending on 28 or 29 activities were considered. These periods are longer than the mentioned FFT maximum. -- Con-struct (talk) 22:46, 3 January 2013 (UTC)[reply]

Looks like original research to me. It's actually 11.1 according to my own FFT, which matches google:

"The number of sunspots peaks every 11.1 years." http://www-das.uwyo.edu/~geerts/cwx/notes/chap02/sunspots.html

"Heinrich Schwabe recognized the 11.1 year solar cycle average in 1843." http://ossfoundation.us/projects/environment/global-warming/solar

Anyway, it varies over time. 71.167.59.239 (talk) 00:30, 24 February 2016 (UTC)[reply]