Visible Sunspot Summary for September 23, 2020

Active Regions Visible Today
0
SESC Sunspot Number
13
Total Sunspot Area
10

Region
Location
Spot Count
Area
AR 2773
N28E62
3
10
Magnetic Class
Spot Class
BETA
BXO
Flare Threat
C: 01%      M: 01%      X: 01%
Date Assigned: Sept. 22, 2020

Noteworthy Events

none


HMI Intensity

HMI Magnetogram

Understanding The Terminology Behind Sunspot Data

Spot Count and Daily Sunspot Number :

The spot count for an active region with only 1 spot visible starts with a minimum number of 11 (1 spot group = (10) + 1 visible spot = (1) , making a grand total of 11). Each visible spotted region that qualifies for active region designation will have its own individual spot count for the day. Typically to qualify, a sunspot region must be large enough to be seen via telescopic observations and be visible for at least 24 hours.

The daily total sunspot number reported is calculated using the following formula. R= Ns + 10 * Ng, with Ns the number of spots and Ng the number of groups counted over the entire solar disk.

Area :

This refers to the sunspot area measured in Millionths to the Sun's visible hemisphere.

Magnetic Class (Mount Wilson Observatory Rules) :

The magnetic class of sunspots is important in determining how potentially volatile particular active regions may be. Sunspots are regularly observed using instruments capable of determining the magnetic polarity of sunspots and active regions. By also applying laws which have been formulated over the years, visual observations can also be used to establish the magnetic polarity and complexity of spot groups. There are basically 7 magnetic types of sunspots that are classified. They are described as follows:

Type

A - Alpha (single polarity spot).
B - Beta (bipolar spot configuration).
G - Gamma (atypical mixture of polarities).
BG - Beta-Gamma (mixture of polarities in a dominantly bipolar configuration).
D - Delta (opposite polarity umbrae within single penumbra).
BD - Beta with a Delta configuration.
BGD - Beta-Gamma with a Delta configuration.

Example: A region labelled as having a magnetic classification of BG indicates that the sunspot region contains a mixture of magnetic polarities, but the dominant polarity of the group is bipolar. Potentially very powerful and potent regions are those which have classifications of BG, BD and BGD. As magnetic complexity increases, the ability of an active region to generate major energetic events likewise increases.

Spot Class (McIntosh Classification) :

The 3 component McIntosh classification is based on the general form 'Zpc', where 'Z' is the modified Zurich Class, 'p' describes the penumbra of the principal spot, and 'c' describes the distribution of spots in the interior of the group.

There are 60 valid McIntosh classifications (see below). Examples: AXX, BXO, EKC, FKO.

 Z-values: (Modified Zurich Sunspot Classification). 
    A - A small single unipolar sunspot. Representing either the
	formative or final stage of evolution.
    B - Bipolar sunspot group with no penumbra on any of the
        spots.  
    C - A bipolar sunspot group. One sunspot must have penumbra. 
    D - A bipolar sunspot group with penumbra on both ends of 
        the group. Longitudinal extent does not exceeds 10 deg.
    E - A bipolar sunspot group with penumbra on both ends. 
        Longitudinal extent exceeds 10 deg. but not 15 deg. 
    F - An elongated bipolar sunspot group with 
        penumbra on both ends. Longitudinal extent 
	of penumbra exceeds 15 deg. 
    H - A unipolar sunspot group with penumbra. 

 p-values:
    x - no penumbra (group class is A or B)
    r - rudimentary penumbra partially surrounds the largest spot.
        This penumbra is incomplete, granular rather than filamentary,
	brighter than mature penumbra, and extends as little as 3 arcsec
	from the spot umbra. Rudimentary penumbra may be either in a 
	stage of formation or dissolution. 
    s - small, symmetric (like Zurich class J). Largest spot has mature,
        dark, filamentary penumbra of circular or elliptical shape with
	little irregularity to the border. The north-south diameter 
	across the penumbra is less or equal than 2.5 degrees.
    a - small, asymmetric. Penumbra of the largest spot is irregular in 
        outline and the multiple umbra within it are separated. The 
	north-south diameter across the penumbra is less or equal than 
	2.5 degrees.
    h - large, symmetric (like Zurich class H). Same structure as type 
        's', but north-south diameter of penumbra is more than 2.5 
	degrees. Area, therefore, must be larger or equal than 250 
	millionths solar hemisphere.
    k - large, assymetric. Same structure as type 'a', but north-south 
        diameter of penumbra is more than 2.5 degrees. Area, therefore, 
	must be larger or equal than 250 millionths solar hemisphere.

 c-values
    x - undefined for unipolar groups (class A and H)
    o - open. Few, if any, spots between leader and follower. Interior 
        spots of very small size. Class E and F groups of 'open' 
	category are equivalent to Zurich class G.
    i - intermediate. Numerous spots lie between the leading and following
        portions of the group, but none of them possesses mature penumbra.
    c - compact. The area between the leading and the following ends 
        of the spot group is populated with many strong spots, with at least
	one interior spot possessing mature peanumbra. The extreme case of
	compact distribution has the entire spot group enveloped in one
	continuous prenumbral area.

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