From: leka@mamane.ifa.hawaii.edu (K.D.Leka)
Subject: Explanation of Solar Reports
Organization: Institute for Astronomy, Hawaii
Date: Tue, 18 Aug 1992 00:05:58 GMT

Hello all;

I've seen this kind of question a few times, so I'm posting a more 
detailed explanation of what these things mean.  Question appeared
a while ago (didn't get the auto-attribution, but author is listed
at the bottom):

>Sunspots at 05.08.1992., 0 h UT.
>
>No.    Pos.  Cl.  Ar.  Mag. SF  F  M  X
>---------------------------------------
>7238 20S 75W Hax  120   a
>7241 14N 50W Dai  230   b    2
>(etc..)
>I have seen the periodic one with explanations but it still doesn't
>answer this question:
>Are there any big and obvious sunspots visible in the next day or so?
>I know big is vague - lets say with welder glass #14, will any be
>visible? How do I tell from the above information?
>Thanks in advance,
>Joe
>joec@morgan.com

So, here is a sample report, the explanation given periodically, and my 
comments on what it means, how to use it for info on observing the sun, etc.

No.    Pos.  Cl.  Ar.  Mag. SF  F  M  X
---------------------------------------
7238 20S 75W Hax  120   a
7241 14N 50W Dai  230   b    2
7242 17N 34W Cao  130   b    9
7245 06S 10E Cso   60   b
7248 12S 41E Dko  500   gd   6
7250 25N 31E Bxo   10   b
7251 17S 37E Bxo   20   b    1
7252 16S 59W Axx   10   a

Optical and x-ray flares in 04.08.92.
Date     Beg. Max. End   Posit. Xray Opt
----------------------------------------
04.08.92 0716 0738 0746 09S 52E C3.1 1F

Explanations of spot columns:
No.  Running number of sunspot group.
	Ok, this is pretty easy - it's just the number assigned to a 
	sunspot group.  This number is given by NOAA, the National Oceanic
	& Atmospheric Administration, in the US...
Pos. Position in Latitude and Longitude.
	This is 'on the Sun'.  Spots come on to the disk in the East, and
	they appear to move West as the Sun rotates.  
Cl.  MacIntosh classification.
	Ok, this is a biggie.  This is also known as the Zurich class of a
	sunspot group, and the three letters are codes for the size & 
	complexity of the group.  (I wrote out at the bottom what these
	are - it's too long for this quick explanation area...)
Ar.  Area in 10-6 of visible hemisphere.
	So, generally anything greater than about 100 in area, one
	should be able to spot w/ a projection device, or small telescope.
	For naked eye stuff, greater than 500 is my guess.
Mag. Magnetic Classification.
a - alpha, b - beta, bg - beta/gamma,
g - gamma, bd - beta/delta, bg - gamma/delta
bgd - beta/gamma/delta.
	Also known as the Mt.Wilson classification system.  
	Again, see below for details, and
	generally the later  & more greek letters, the more complex
	(and more flare productive it will generally be.)
SF   Number of subflares.
	Won't see these by eye or small telescope
F    Number of optical flares. (importance > 1).
	If you're lucky, might see these w/ a Hydrogen-alpha filter
	on a small telescope.   Gotta time it right, though!  :-)
	The longest, brightest optical flares last on average about 0.5-1.0hr.
M    Number of medium x-ray eruptions.
	Will cause slight disturbances in the earth's atmosphere in the
	following days, *depending upon where on the sun they happened*
X    Number of strong x-ray eruptions.
	Same as above but more probably strong atmospheric disturbances.
-------

So, here's an annotated example report:

No.    Pos.  Cl.  Ar.  Mag. SF  F  M  X
---------------------------------------
7238 20S 75W Hax  120   a		-might see it, but boring
7241 14N 50W Dai  230   b    2		-will see it w/ binoc's, but boring.
7242 17N 34W Cao  130   b    9		-again small, but more active(might
					be brighter in an H-alpha filter
7245 06S 10E Cso   60   b		-forget it..
7248 12S 41E Dko  500   gd   6		-Close to disk center, big, and not
					a simple configuration - looks like 
					it would be interesting to look at!
7250 25N 31E Bxo   10   b		-Yawwn...
7251 17S 37E Bxo   20   b    1		-ditto.
7252 16S 59W Axx   10   a		-don't bother..

-------
Ok, the Zurich Classification system:
FIRST LETTER:
A-a small single sujnspot or very small group of spots with the 
	same magnetic polarity, without penumbra
B-Bipolar sunspot group, no penumbra
C-An elongated bipolar sunspot group.  One sunspot must have penumbra,
	and penumbra does not exceed 5deg. in Longitudinal (E-W) extent
D-An elongated Bipolar sunspot group, penumbra on both ends, longitudinal 
	penumbra extent between 5 & 10deg.
E-same but w/ penumbra extending between 10 & 15 deg.
F-same w/ penumbra extending more than 15deg.
H-A unipolar sunspot group with penumbra.  ClassH sunspot groups become compact
	Class D or larger when the penumbra exceeds 5deg in long. extent

SECOND LETTER:(the penumbra type of the largest spot in the group)
x-no penumbra
r-rudimentary
s-small (lt. 2.5deg. N-S diameter), symmetric
a-small, asymmetric
h-large (gt. 2.5deg. N-S diameter), symmetric
k-large, asymmetric

THIRD LETTER: (the compactness of the group);
x-a single spot
o-open
i-intermediate
c-compact

and, the Mt. Wilson Classification:

Alpha: A unipolar sunspot group
Beta: A sunspot group having both positive & negative magnetic polarities
  (bipolar) with a simple and distinct division between the polarities.
Gamma: A complex active region in which the positive and negative polarities
  are so irregularly distributed as to prevent classification as a bipolar
  group.
Beta-Gamma: a sunspot group that is bipolar but which is sufficiently complex
  that no single, continuous line can be drawn between spots of opposite 
  polarities.
Delta: a qualifier to magnetic class, indicating that umbrae separated by less
  than 2 degrees within one penumbra have opposite polarity.
Beta-Delta: A sunspot group of general beta magnetic classification
  but containing one or more delta spots.
  (similarly for Beta-Gamma-Delta, and Gamma-Delta)

(Classification system explanations from the SESC Glossary of 
Solar-Terrestrial Terms, NOAA/USAF SESC, Aug 1988)


Thanks to:
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for giving us these reports!

Hope this helps!  Happy Sun-gazing (w/ protection, of course!)

		-KD
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Osborn's Law: "Variables won't; constants aren't; constraints don't"
K. D. Leka			Internet: leka@mamane.ifa.hawaii.edu
Institute For Astronomy		Bitnet:	kleka@susolar
University of Hawaii
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