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 Post subject: Counting sunspots
PostPosted: Mon May 13, 2019 2:47 pm 
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Joined: Thu Jun 02, 2016 11:32 am
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Location: New Farnley, Leeds lat 53.8N long 1.6W
Now then Chap(esse)s, here's a little conundrum. Our good friend Cliff has often remarked on the subjectivity of counting sunspots. So, let's bring this fuzzy little topic out of the closet; I've been thinking about it this lunchtime over a few glasses of wine in the back garden wi' t'wife.
To set the scene I give you my visual solar observation of today as follows:
2019 May 13, 0940 UT, seeing 1-2, transparency 2, 80mm refractor F11.4, 15mm plossl eyepiece, by projection in white light, 2 sunspot groups, 8 sunspots in total. Remarks, the f (following) group consists of 1 large spot with 2 umbrae, the larger component itself being completely divided by a narrow light bridge, the p (preceding) group consists of 1 small dark spot surrounded at a distance by 6 (more were suspected but not counted) small, faint, elusive, ill-defined grey spots, some of which appear elongated.
I counted them all as spots for the daily record. The little "grey ghosts" don't look like proper spots; nevertheless I count them as such on the basis that if it's darker than the photosphere in white light by projection, it's a spot (if it's brighter it's a bit of faculae or a flare), and I've seen them before at large projection scales when the photosphere is sufficiently dimmed so as not to glare them out.
What do you count as a sunspot?

Bob


Last edited by RMSteele on Thu May 16, 2019 2:30 pm, edited 1 time in total.

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 Post subject: Re: Counting sunspots
PostPosted: Wed May 15, 2019 9:29 pm 
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Location: Manchester
Bob
Now recovered I think I'll be brief this time.
The Sun is now the only astronomical object I feel physically comfortable observing\imaging. Whilst ironically, I do not feel mentally comfortable about Sunspot counting (spoiling my fun !).
If it weren't for the Sun I might lose interest in astronomy altogether.
Best wishes from Cliff


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 Post subject: Re: Counting sunspots
PostPosted: Thu May 16, 2019 9:03 am 
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Location: New Farnley, Leeds lat 53.8N long 1.6W
Dear Cliff, Thanks for replying. Yes the Sun is a good source of interest, always changing and free from the physical inconvenience and stress of night observation. I raised the topic because I think that most of us "sunspot counters" are far more subjective in our approach than we care to talk about!
Kind thoughts, Bob


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 Post subject: Re: Counting sunspots
PostPosted: Sat May 18, 2019 10:06 pm 
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Bob
Several years back I read an article in a general scientific but not solely astronomy magazine. It was about an American astronomer who had studied historical Sun observing very deeply for several years. His subsequent findings were quite surprising. I can't remember that American's name. However, from what I vaguely recall amongst other things he was quite critical of early 19th century UK Sun observations. Whilst I think it was the Zurich Observatory Director, a post recognised as the leading authority of the Sun for about 100years did some peculiar things about the 1950s. In particular he modified the way individual observers Sun counts were adjusted. Something that had been the same for a very long time. But for some unknown reason he only told some of his immediate associates what he was doing. Whatever, I think the Sun Headquarters were moved from Zurich. I think there were several other things the American found in his researching which the general professional astronomical authorities were not happy about. After reading the article I was surprised that nothing seemed to appear in our UK astronomy magazines. But eventually it was reported that some sort of international sub-committee was set up to look into the American's concerns. Eventually after another year or so they made a report in which the American did not come out of things very well but it did result in professional astronomers making some important changes. I must admit the matter did leave me feeling a little bewildered.
best wishes from Cliff


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 Post subject: Re: Counting sunspots
PostPosted: Sun May 19, 2019 10:39 am 
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Location: New Farnley, Leeds lat 53.8N long 1.6W
Hello Cliff, Thanks again for your comments. Yes, some years ago there was a chap who was “The Keeper of the Count” (of sunspots) so to speak and, apparently he decided to change the statistical method of counting. He was unhappy that a spot was counted as “one” whether or not it was, say, a huge unaided eye monster or a tiny thing. So, he weighted his count by multiplying the value of a large spot by 5. I think that’s what happened and if my memory is inaccurate, no doubt someone will correct me. Anyhow I don’t think anyone is too bothered that he did that from a statistical perspective, it’s just that he didn’t attempt to apply a correction to the older data, nor did he tell the rest of the astronomical community what he was doing, or what they should be doing – he didn’t put it up for debate or publish his methodology as far as I know. Thus it was all a bit unwelcome and embarrassing when the whistle was blown in the 1990’s; and I gather the whistle blower was not popular!
However that situation is for the big boys to sort out. What I am really getting at is a mini version of that situation. There are lots of us amateur sunspotters contributing obs to various organisations. I have been projecting the Sun for fun for decades with very small apertures (even 10x50 binocs) and counting spots for my own amusement: when I joined the SPA I started to send them in regularly. Now, if a SPA beginner were to ask me exactly what do you count as a discrete sunspot, I would probably turn into captain Mainwaring and say “Yes, er glad you asked that, Pike.” And tell them to ask the Solar Director! …….. because I have asked myself that same question on many occasions.
One might beg the question by saying “just count the individual spots that you can be sure of seeing as separate spots, larger or smaller telescopes will give different results that can be statistically allowed for”.
I could go on and on much to the annoyance of those who don’t want beginners to be put off. But really detailed amateur advice is hard to find. Hence I suspect, Cliff, your own reluctance to count sunspots! I am not criticising anyone here. I could set out all my own criteria for counting sunspots in the minutest detail, but while I am happy that I am myself consistent in the way I count sunspots, I am equally certain it would only generate criticism and more requests for greater clarity.
Of course this kind of objective/subjective conundrum pops up in all kinds of observing and I suppose if you stick at it you come to a point where you develop your own consistent approach. That’s when you become “experienced” and avoid the term “expert”, and avoid giving gratuitous opinions.
Which is worse, the silence of the Wolfs, or the silence of the pro-ams?
Kind thoughts, Bob


Last edited by RMSteele on Fri Jul 19, 2019 1:57 pm, edited 1 time in total.

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 Post subject: Re: Counting sunspots
PostPosted: Mon May 20, 2019 9:08 am 
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Now that you've mentioned doing it Bob, projecting the Sun with binoculars isn't recommended. The eyepiece lenses are cemented and can be damaged by the heat.

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brian


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 Post subject: Re: Counting sunspots
PostPosted: Mon May 20, 2019 2:51 pm 
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Joined: Thu Jun 02, 2016 11:32 am
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Location: New Farnley, Leeds lat 53.8N long 1.6W
I'm sure you're right Brian, perhaps I should have made it clearer about binocs. Mine were (and are - coz I've still got 'em!) Zeiss Jena 10x50 with a metal body and bracketed, not cemented, glass prisms. The eyepieces, while probably cemented (David will probably know for sure) have suffered not the slightest damage from 39 years of doing this. I would not, however, do it with modern binocs. And to be doubly clear (joking apart) I would NEVER NEVER look through them at the Sun, not even with any kind of solar filter. Kind thoughts, Bob


Last edited by RMSteele on Fri Jul 19, 2019 1:59 pm, edited 1 time in total.

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 Post subject: Re: Counting sunspots
PostPosted: Mon May 20, 2019 8:37 pm 
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Bob
There's a lot to be said for simple stargazing & not bothering too much about serious science.
Personally I feel quite disappointed about the way important international astronomical bodies apparently treated the American astronomer. Seemingly largely covering things up. Although I gather those astronomical bodies have made some changes though without giving our American friend much, if any, credit at all. However, in my humble opinion, I suspect if it hadn't been for that American things would have continued to bumbling along in the same old fashioned incompetent way.
Best wishes from Cliff


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 Post subject: Re: Counting sunspots
PostPosted: Mon May 20, 2019 9:22 pm 
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Location: New Farnley, Leeds lat 53.8N long 1.6W
Cliff, I agree. Anyway, I wouldn’t worry about it: after all the Universe is a work of art, not science and science is just a form of art appreciation – any hereandthere quantum will tell you that. Seems no-one likes being held to account over precisely how to count sunspots, wisely perhaps? Bob


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