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Ken Nakayama used two filters ND400 on a 60mm refractor telescope at 910mm of focal length to take this sharp image of the Sun. The camera employed is Canon D350 also known in Japan as Canon kiss Digital N. At right side a sunspot becomes evident with a great deal of detail.
 
 
2015-10-18 15:33:29       
Leave a Comment A few weeks ago 3 groups of solar scesttiins released a joint press release at the 2011 meeting of Solar Physics Division (SPD) of the American Astronomical Society. Each group presented a unique set of solar observations, which together they interpreted as showing the Sun is headed towards a period of extended low activity not solar maximum. There has been very little noticeable solar activity since the exiting event of June 7, 2011. Could this mean that those 3 groups of solar scesttiins are correct? Maybe not (For more on solar activity and the solar cycle.)
 
2015-10-18 15:33:28       
Leave a Comment A few weeks ago 3 groups of solar scesttiins released a joint press release at the 2011 meeting of Solar Physics Division (SPD) of the American Astronomical Society. Each group presented a unique set of solar observations, which together they interpreted as showing the Sun is headed towards a period of extended low activity not solar maximum. There has been very little noticeable solar activity since the exiting event of June 7, 2011. Could this mean that those 3 groups of solar scesttiins are correct? Maybe not (For more on solar activity and the solar cycle.)
 
2012-10-07 16:01:28       
The purpose of the LSC is supsdpeoly to get a sunspot number that Rudolf Wolf would have counted. Wolf did not [on purpose] count the smallest specks and pores. Later observers pointed out that the decision on what not to count was then very arbitrary [as there was no precise definition of what not to count]. A better method [and that is used by everybody since the 1880s] is to count everything you can see [with a given telescope]. Since different people have different acuity [and experience] they would still count differently, but that can be measured by comparing with others.Wolf used a 8 cm aperture refractor at magnification 64 in the 1850s. This telescope still exists and is still being used. Wolf did not observe during the Dalton minimum [almost nobody did] and the sunspot number he reconstructed for that time is mainly based on counts of aurorae and simple interpolation between the very sparse actual observations.From 1861 on, Wolf mostly used an even smaller telescope [handheld and portable - as he was often on travel]. He determined that he needed to multiply the counts with that smaller scope by 1.5 to match what he would count with the 8 cm ‘standard’ telescope. His assistant, Wolfer, was using the 8 cm in parallel with Wolf for 17 years and determined that to get to the same count as Wolf, he would have to multiply his own counts [which included everything] by 0.6. So now we have this convoluted scheme: Wolf counts 20 [say] with the small handheld scope, multiplies that by 1.5 getting 30 and claims that that is what he would have counted with the 8 cm. Wolfer using the 8 cm [counting everything] counts 50, then multiplies by 0.6: 50*0.6 = 30, as an estimate of what Wolf would have counted. With me so far?The Wolfer count is the better method [as it is better defined], but Wolfer wanted to stay compatible with the old [already published] Wolf list, so the 0.6 factor has become the ‘conversion’ factor between the ‘all count’ and the Wolf count. Now, the LSC people think that the Wolf number ‘is under threat’ [by some conspiracy it seems] and want to restore the count to ‘what Wolf would have counted’. The reason for this seems to be the desire to show that we are entering a Dalton-type grand minimum, and the official count is claimed to be [nefariously] too high, so needs to be reduced to fulfill the prophesy. The way to reduce the official count is to remove groups that are too small [below a 'threshold'] and subtract their contribution from the official SIDC sunspot number. So, here is what is wrong with the LSC:1) Wolf did not observe during the Dalton minimum, so there are no ‘Wolf numbers’ to reproduce2) The threshold [for throwing out groups] is uncalibrated. I.e. there were no comparisons on which the threshold is based other than ‘it seems to be a good number’3) The factor 0.6 that is used by SIDC already takes into account the conversion from Wolfer to Wolf4) The notion that the modern counts by SIDC is too high [for political reasons] while, in fact, comparisons with hundreds of other [amateur] observers and even with the NOAA count show that the official SIDC count since ~2001 has been slightly [~12%] too low.================================Leif. Thank you for taking the time to explain your position so clearly. I see your point that if it is arbitrary where Layman and earlier Wolf makes the cut between which sunspots are counted and which not, that creates a serious problem.But I also see Layman’s point that in a period with many little sunspots that Wolf would not have counted, the Wolfer number would be higher than Wolf’s and when there are mostly big sunspots, the Wolfer number would be lower. If there are 10 tiny specks, Wolf would have given a sunspot number of 0, while Wolfer would count 10 times 0.6 = 6.If there are 10 big sunspots, Wolf would have given a sunspot number of 10, and Wolfer again 10 times 0.6 = 6. It seems to me that if we go back to the period when Wolfer came up with his conversion factor of 0.6, we could get a reasonably accurate idea of what Wolf counted and what not supposing that Wolfer kept accurate records of how many big or small sunspots were that he saw.Did he?Concluding, I would say that the Wolfer sunspot number gives a consistent and trustable sequence of sunspot numbers from Wolfer onwards.The Wolf number is an interesting addition to that, and helps extend the sequence, if it is possible to find a threshold that can be reasonably argued to correspond with Wolf’s. In any case, you clear explanation makes Layman’s accusations of bad intentions behind the SIDC-numbers look silly. Thanks again.
 
2011-08-19 16:14:04       
Thanks for writing such an easy-to-udnertsand article on this topic.
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