The legend of Observation log for Wolf Sunspot Number:
- Polar angle (P)... The tilt-angle of solar axis from the celestial north direction at observed time. The values have plus when the axis leans to the left and minus in right.
- Central latitude (B0)... The tilt-angle of solar axis in radial direction at observed time. The values have plus when solar northern hemisphere looks more area than southern region, and have minus in opposite case.
- Central longitude (L0)... This value represents the heliographical longitude at the central meridian line. L0 value decreases about 13.2 degrees per day and returns at same value every 27.3 days.
- The revised Wolf numbers of sunspot (R') of the northern and southern hemispheres have been calculated separately with an equation of R' = k (10 g' + f ).
k ... Correction factor of deviation between observers. This site has set to be k = 1.0.
g' ... Number of active regions detected in Hα solar images.
f ... Total number of sunspots including the penumbra detected in white-light solar images.
This site has calculated the revised Wolf number, R' including active regions without sunspots as "Group with zero-sunspots".
Please bear in mind that the calculation method is different from that with the general definition.
The table legend of active regions (sunspot groups):
- Group No. ...Originally assigned serial number of active regions since May 2007.
Letters N and S denote that respective regions have been observed in the northern and southern solar hemispheres.
- NOAA A. R. (Active Region) ... The serial number of active regions assigned by the NOAA (National Oceanic & Atmospheric Administration).
N/A (Not assigned) means that the active region was detected in this observation but not observed by the NOAA.
- Position ... The heliographical longitude and latitude of center of respective active regions.
- Obs. dates ... Number of observed dates of respective regions in this site.
- Type ... This site has indicated the Zurich classification system of respective sunspot groups.
A ... One or more tiny spots that do not demonstrate bi-polarity or exhibit penumbra.
This site has classified regions without sunspots in type "A" as an original treatment.
B ... Two or more tiny spots that demonstrate bi-polarity but do not exhibit penumbra.
C ... Two or more spots that demonstrate bi-polarity and unilateral spot has a penumbra.
D ... Two or more spots that demonstrate bi-polarity, both spots display penumbras and at least one of them exhibits simple shape. The type occupies 10 degrees or less in solar longitude.
E ... This type is similar to the D-type but many small spots distribute between principal spots and spreads between 10 and 15 degrees in solar longitude.
F ... Largest and most extensive of groups, similar to E-type but covers in excess of 15 degrees in solar longitude.
G ... The decayed remnant of "D", "E", and "F" groups without accompanying small spots. Demonstrates a bi-polar group with penumbras and occupies over 10 degrees in solar longitude.
H ... The decayed remnant of "C", "D", "E", and "F" groups. A single spot group with penumbra. Must be larger than 2.5 degrees in diameter. This type occasionally is accompanied by a few small spots.
J ... The same as the "H" type but has a diameter less than 2.5 degrees.
- Max. size ... Maximum heliographical range of respective regions.
- Evolved Obs. date ... This column indicates the observed date and linked to corresponding pages when respective regions had maximum number of sunspots.
In case that the region had maximum sunspots over multiple dates, the table has indicated a date when the region was closest to the central meridian line.