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How to count sunspots?

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davidjayjackson's picture
How to count sunspots?


I actually read a thread from back in April of this year, that helped a little.

And Ialso  read a handbook written for the Astronomical League.

But I need to have this dummied down for me a little?

So If I'm  using the SunEntry system to enter my data.

If today while observing the Sun I see:

5 independant sunspots

2 groups containing a total of 5 sunspots

In SunEntry do I enter a 2 for groups and 10 for sunspots?


Thanks in advance,



ASA's picture
Wolf Number.

Hi David.

the Wolf. Number:,

Wolf number (10g + f) 

5 independant sunspots = 5 groups (50) + 5 sunspots (5)= 55

2 groups containing a total of 5 sunspots=2 groups(20) + 5 (5) sunspots.= 25

Wolf: 80..



In SunEntry do I enter a 2 for groups and 10 for sunspots?





HRHA's picture
Zuric groups and sunspot counts

Hi David, Salvador,

There are two important things to understand about counting groups and sunspots, I think. First the AAVSO, since the begining in 1944, has adopted the Zurich classification of groups and sunspots:

Second, this classification was originally from Wolf the director of the Zurich observatory back in 1860:

There are other classification schemes for sunspot counting, McIntosh, Boulder, etc. (See attached .ppt), however since the AAVSO has a long history of using the Zurich scheme, it would be preferable it that method were used.  

Hope this helps.








davidjayjackson's picture
Salvador, Rodney: Thanks for

Salvador, Rodney:

Thanks for taking the time to respond to my post.

That being said I think you guys might have missed the second part of my question, "What do I enter into SunEdit"?

Athough after I little tinkering with SunEdit it seems that there are two options for entering the values for "Group and Spots"

 I could enter to total groups 7 and total spots 10 which give the total Wolf count of 80.

Or I can enter two records one for sunspots and one for groups?

Thanks again.



onj's picture
Hi David, I think you got it.

Hi David,

I think you got it. But to be clear:

1. Add up the number of groups. Note that a group may have just one spot. Enter that number in the 'Groups' box in SunEntry. So in your example that is 7.

2. Add up the total number of spots. Enter that number in the 'Spots' box in SunEntry. So in your example that is 10.

Given 1 and 2 above, SunEntry will automatically calculate and enter the Wolf Number, so there need to enter it manually. In your example SunEntry will calculate 80 for the Wolf Number.

There is just one record for each day you observe (you should only make only one observation per day).




HNL's picture
sunspots counting

Hi:  Great and have  a good time.  I still enjoy checking out the sun. Hope to bring my scope to the AAVSO. annual meeting.  I found my time being taken up by alot of caregiving these days. Best HNL

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