Affiliation
American Association of Variable Star Observers (AAVSO)
Mon, 04/22/2024 - 01:19
Hi. I am a long time member of the AAVSO, but a newcomer to solar observing. I could use some guidance about counting the number of groups. With so many spots right now, it is sometimes difficult for me to decide where one group stops and another starts. For example, today's SpaceWeatherLive.com showed the attached chart of "sunspot regions." Do "regions" equal groups? Are regions 3647 and 3645 two different groups, or part of one very large group? Thanks for your help. Tom.
I am unable to attach the .jpg file, so I could use some help with that too.
Hi Tom,
And welcome to the Solar Section. We use the Zurich Classification system to record groups and sunspots:
https://www.aavso.org/zurich-classification-system-sunspot-groups
NOAA uses satellite images to classify their active regions and splits the grouping into many smaller parts. We encourage you not to split the groups, but look to the Zurich method. We try to keep to the historical method of recording for continuity with the past AAVSO data. Here might be some advice from SILSO:
https://www.sidc.be/SILSO/faq-page
Are you using your 5 inch refractor? That is somewhat a large aperture for observing we recommend an aperture of 60 - 70 mm, and a magnification of 40 X or there about, so we don't over count the groups. Yesterday I counted 6 groups some E and F and one an A and two H by the Zurich classes. In all those groups I counted 42 sunspots. I use a 60 mm aperture.
Rodney (HRHA)
Thanks for the information. Actually for solar observing I am using an 80mm refractor. I find that the maximum useful magnification is about 50x. I understand the Zurich classes of the groups, but still find it a bit confusing when two groups are fairly close together and might be considered as one type E or F group. Thanks for clearing up the distinction between "active regions" and "groups." - very helpful.
I'm at a similar place in my experience with counting, which I started doing last summer. Determining the number of groups is a challenge right now, and I have started making sketches every day to help me track the movement of the groups. I also try to study the structure for clues of spots being in a common group. I think experience will probably help the most for new observers (like me!). I'm using a Questar 3.5" with the off-axis solar filter which stops it down to 40mm.
Mike
I have been observing with an 8" Dobsonian, using a magnification of around 48x; I could get decent images through my OnePlus mobile phone attached to a mobile adapter. Counting sunspots is a patient task, but groups are easily identifiable especially the penumbral regions. In case there is confusion between E & F, I used a grid to estimate the degrees occupied by the sunspots in the group on the Sun's surface. In the Zurich classification system, sunspots are also differentiated according to degrees occupied on the Sun's surface. That is a very helpful measure.
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